"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:7f46a0aa-6bd9-4efb-b611-eec71f021c8c","http://resolver.tudelft.nl/uuid:7f46a0aa-6bd9-4efb-b611-eec71f021c8c","Introducing the 3DCityDB-Tools Plug-In for QGIS","Agugiaro, G. (TU Delft Urban Data Science); Pantelios, Konstantinos (Student TU Delft); León Sánchez, C.A. (TU Delft Urban Data Science); Yao, Zhihang (virtualcitySYSTEMS GmbH); Nagel, Claus (virtualcitySYSTEMS GmbH)","Kolbe, Thomas H. (editor); Donaubauer, Andreas (editor); Beil, Christof (editor)","2024","This paper introduces a new plug-in for QGIS that allows to connect to the free and open-source 3D City Database to load CityGML data, structured as classic GIS layers, into QGIS. The user is therefore not required to be a CityGML specialist, or a SQL expert, as the plug-in takes care of hiding from the user most of the complexity in terms of underlying data model and database schema implementation. The user can therefore load CityGML thematic “layers” (e.g. for buildings, bridges, vegetation, terrain, etc.), explore their geometries in 2D and 3D and access and edit the associated attributes. At the same time, depending on the user privileges, it is possible to delete features from the database using either normal QGIS editing tools, or a “bulk delete” tool, also included. The plug-in is composed of two parts, a server-side one, which must be installed in the 3D City Database instance, and the client-side one, which runs as a QGIS plug-in in strict sense. A GUI-based tool is also provided for database administrators in order to install/uninstall the database-side part of the plug-in, and manage users and their privileges. All in all, the 3DCityDB-Tools plug-in facilitates the access to CityGML data for GIS practitioners from heterogeneous fields and expertise with the common denominator being the well-known QGIS environment.","3D city database; QGIS; CityGML; CityJSON; Plug-in","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-21","","","Urban Data Science","","",""
"uuid:2caaaa11-b205-4021-8f34-c6d5ad8f38a7","http://resolver.tudelft.nl/uuid:2caaaa11-b205-4021-8f34-c6d5ad8f38a7","cjdb: A Simple, Fast, and Lean Database Solution for the CityGML Data Model","Powałka, Leon (Student TU Delft); Poon, Chris (Student TU Delft); Xia, Yitong (Student TU Delft); Meines, Siebren (Student TU Delft); Yan, Lan (Student TU Delft); Cai, Yuduan (Student TU Delft); Stavropoulou, G. (TU Delft Urban Data Science); Dukai, B. (3DGI); Ledoux, H. (TU Delft Urban Data Science)","Kolbe, Thomas H. (editor); Donaubauer, Andreas (editor); Beil, Christof (editor)","2024","When it comes to storing 3D city models in a database, the implementation of the CityGML data model can be quite demanding and often results in complicated schemas. As an example, 3DCityDB, a widely used solution, depends on a schema having 66 tables, mapping closely the CityGML architecture. In this paper, we propose an alternative (called ‘cjdb’) for storing CityGML models efficiently in PostgreSQL with a much simpler table structure and data model design (only 3 tables are necessary). This is achieved by storing the attributes and geometries of the objects directly in JSON. In the case of the geometries we thus adopt the Simple Feature paradigm and we use the structure of CityJSON. We compare our solution against 3DCityDB with large real-world 3D city models, and we find that cjdb has significantly lower demands in storage space (around a factor of 10), allows for faster import/export of data, and has a comparable data retrieval speed with some queries being faster and some slower. The accompanying software (importer and exporter) is available at https://github.com/cityjson/cjdb/ under a permissive open-source license.","CityGML; 3DCityDB; 3D modelling; DBMS; CityJSON","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-21","","","Urban Data Science","","",""
"uuid:f051beba-b13f-42f9-a8d2-4c539fd36039","http://resolver.tudelft.nl/uuid:f051beba-b13f-42f9-a8d2-4c539fd36039","Digital geoTwin: A CityGML-Based Data Model for the Virtual Replica of the City of Vienna","Lehner, Hubert (Vienna City Administration); Kordasch, Sara Lena (Vienna City Administration); Glatz, Charlotte (Vienna City Administration); Agugiaro, G. (TU Delft Urban Data Science)","Kolbe, Thomas H. (editor); Donaubauer, Andreas (editor); Beil, Christof (editor)","2024","This paper presents a CityGML-based data model developed for the semantic 3D city model of Vienna, Austria. The data model consists in a profile of the CityGML 2.0 standard and has been extended by means of an Application Domain Extension (ADE) developed by the Department for Surveying and Mapping of the City of Vienna in order to comply with the current and future needs of the municipality. The definition and adoption of such data model are a fundamental part of Vienna’s “Digital geoTwin” project. The core of the strategy is to process the 3D measurement data of the surveying and mapping department from existing as well as new measurement methods directly into a Digital geoTwin—a virtual, semantic 3D replica of all objects in the city—and to derive other geodata products (city map, elevation models, etc.) from this 3D model. Furthermore, the Digital geoTwin should serve as a geometric and semantic basis for a digital twin of the City of Vienna. In order to define the data model for the Digital geoTwin, 3D modelling of all city objects has been carried out in a test area of the city, followed by a mapping of the objects to the CityGML data model. In an iterative development process, conceptual gaps have been identified, analysed and eventually formalized into a UML-based Application Domain Extension. Additionally, the free and open-source CityGML 3D City Database (3DCityDB) has been used for storage after being extended accordingly, and FME workbenches have been created to transform and import the original source data into the 3DCityDB and therefore test the suitability of the developed data model.","Digital geoTwin; Urban digital twin; Data modelling; 3D city model; CityGML ADE","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-21","","","Urban Data Science","","",""
"uuid:4144e477-780e-4328-8251-7a8f98d67533","http://resolver.tudelft.nl/uuid:4144e477-780e-4328-8251-7a8f98d67533","Integrating CityGML and LADM for 3D Building Management - Taking Taiwan as an Example","Ho, Sin-Yi; Hong, Jung-Hong","","2023","The recent advances of surveying and mapping technology has made the collection of 3D information increasingly easier. A variety of real-world phenomena nowadays can be modelled in a realistic way, which enables the development of many innovated applications (Liu Wei Zhe, 2020). Due to the rapid expansion of urban population and limited land resources, the effective management of the right and property of buildings has been considered as one important mission to the digital cadastre. Especially when more and more tall buildings were built in the urban area, modern 3D modelling strategies considering vertical dimensions appears to be an obvious choice for the future cadaster systems. Developing 3D cadastres is therefore widely recognized as an urgent issue for many countries (Zeng Zis Han, 2022). To meet the modelling and encoding demands of city phenomena, CityGML (City Geographic Markup Language) from Open Geospatial Consortium (OGC) has been successfully used to improve the cross-discipline interoperability with its pre-defined and standardized schema (Löwner, Gröger, Benner, Biljecki, & Nagel, 2016). Nowadays, many 3D building datasets around the world are distributed with CityGML (OGC, 2021a). Land Administration Domain Model (LADM) provided a standardized schema for the management of building property rights (Lemmen, van Oosterom, & Kalantari, 2018), which includes contents about party, administrative units and the right, responsibility and restriction between them. The combination of a 3D model and property rights brings great benefits to the development of 3D cadaster (Surmeneli, Koeva, Zevenbergen, & Alkan, 2020), for example, realizing the size and the location of the legal space. Various research has been focusing on the advantages of integrating these two standards. Rönsdorff et al. (2014) proposed a CityGML ADE to model the legal space; Góźdź et al. (2014) proposed a CityGML-LADM ADE model to describe the relationship between the legal and physical representation of selected objects. Nega & Coors(2022) suggested the integration of LADM and CityGML can be used to deal with the problems of overlapping ownerships in buildings, and can be further applied in many scenarios which need to distinguish the legal and physical space. LADM can effectively model the legal and management aspect about buildings, but more discussion about the 3D geometric representation, as well as the links to the various 3D building information, e.g., BIM, 3D mesh model, are still necessary. By considering the regulation, management systems and building characteristics of Taiwan, this research discusses the design strategies for developing a prototype of 3D cadastre system for Taiwan using CityGML and LADM. Although the current result is still preliminary and the modelling scope is limited, we believe it can serve as the basis for further profile development of a complete 3D cadastre system that not only meets the demands of cadaster related application, but also provide a solid reference for the use of land information in smart cities applications.","Building Management; CityGML; LADM; 3D cadastre","en","conference paper","","","","","","","","","","","","","",""
"uuid:6786ac5c-b61d-4e17-8501-e3cf2c7a9577","http://resolver.tudelft.nl/uuid:6786ac5c-b61d-4e17-8501-e3cf2c7a9577","Further Development of a QGIS Plugin for the CityGML 3D City Database","Mbwanda, Tendai (TU Delft Architecture and the Built Environment)","Agugiaro, G. (mentor); León Sánchez, C.A. (mentor); Delft University of Technology (degree granting institution)","2023","Diversity in the use cases of semantic 3D city models today is unprecedented. A key enabler for this is the CityGML standard developed by the OGC to facilitate storing and exchanging these city models. Nevertheless, CityGML only provides object definitions which cater for a wide range of applications, making necessary the need to attach additional semantic information specific to each domain. For this reason, CityGML was designed with generic components that allow it to be extended. Alternatively, an extensibility mechanism that strengthens semantic interoperability in data exchange is the ADE. An example is the Energy ADE which augments CityGML for Urban Energy Modelling at single-building and city-wide scales. Base CityGML datasets are commonly encoded using the XML, though there are other encodings based on the JSON and SQL. The latter encoding is favourable for its associated benefits that come from the underlying DBMS. The 3DCityDB , upon which this thesis is based, is one such encoding that is open source and developed for PostgreSQL and Oracle. It has a complex structure which makes it difficult for users without extensive knowledge of CityGML, databases and SQL to access data. Hence, the 3DCityDB-Tools plugin was developed to simplify user interaction with the 3DCityDB using QGIS. However, encoding an extended CityGML dataset in the 3DCityDB adds greater complexity to a system that is already complex. In addition, 3DCityDB-Tools currently has no support for ADEs. On this backdrop, this research was initiated to investigate the extent to which ADE support can be introduced to the 3DCityDB-Tools plugin. Its server-and-client-side components are further developed to have extended layers that interact with data in 3DCityDB tables, can be managed from the GUI in QGIS and whose attributes are editable. This was achieved in an incremental and iterative process while maintaining the current architecture and user experience of the plugin. Areas identified for future development relate to the underlying database encoding of CityGML and capabilities not yet supported.","CityGML; 3D City Database; Application Domain Extension; QGIS","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:d253b343-7c96-45ee-9239-5c85594ad4fa","http://resolver.tudelft.nl/uuid:d253b343-7c96-45ee-9239-5c85594ad4fa","Mapping the Energy ADE to CityGML 3.0","Bachert, Carolin (TU Delft Architecture and the Built Environment)","Agugiaro, G. (mentor); León Sánchez, C.A. (graduation committee); Kutzner, T. (graduation committee); Delft University of Technology (degree granting institution)","2023","In order to limit the global warming to well below 2 degrees Celsius, all sectors have to reduce their greenhouse gas emissions and become more sustainable. This also includes the building sector, which is in Europe responsible for 40% of the total energy consumption (European Commission, 2020). A way to work towards this goal is by retrofitting the existing building stock to become more energy efficient. Urban Building Energy Modelling (UBEM) can help in this endeavour by identifying energy-saving potentials and thus to effectively allocate the required resources (Horak et al., 2022). Yet, UBEM involves many stakeholders which is why standards are crucial to facilitate data exchange and interoperability among them. In this context, the Energy ADE v1.0 was developed as an extension for the semantic 3D city model standard CityGML 2.0. It serves two purposes, first by storing energy related information on the individual building level, and second by providing the necessary input data for UBEM simulations (Agugiaro et al., 2018). However, in September 2021 CityGML 3.0 was released. The introduced changes directly affect the structure of the Energy ADE, which is why it cannot fully function on it anymore. This thesis therefore answers the question, how and to what extent the Energy ADE for CityGML 2.0 needs to be adapted to be conformant with the new CityGML 3.0 standard. It is accomplished by following a model-driven approach, where the UML class diagrams for the mapped Energy ADE are created first, before automatically deriving the corresponding XSD schema file. Through the lossless mapping itself, the Energy ADE is integrated as much as possible into CityGML 3.0, while also maintaining a logical symmetry. As such it accounts for the introduced changes of CityGML 3.0, by making use of the space and geometry concept, the versioning possibilities as well as the provided structures to model time-dependent data. The result is eventually tested and verified by converting a sample dataset to the Energy ADE for CityGML 3.0. This work provides an example on how other ADEs can be adapted to fit the new CityGML 3.0 standard and thus hopefully to the further establishment of it.","CityGML; Energy ADE; Urban Energy Modelling; 3D city model","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:f089b54c-3baf-4e19-bf24-0db92e0bf95f","http://resolver.tudelft.nl/uuid:f089b54c-3baf-4e19-bf24-0db92e0bf95f","New Techniques and Methods for Modelling, Visualization, and Analysis of a 3D City","Ying, Shen (Wuhan University); van Oosterom, P.J.M. (TU Delft Digital Technologies); Fan, Hongchao (Norwegian University of Science and Technology (NTNU))","","2023","The recent years observe the vast development in new techniques and methods for modelling, visualization, and analysis of 3D digital cities, as the need of digital twins of urban environment in different applications and simulations has been increased dramatically. This special issue attempts to give an overview of the recent progress and future tendency of research activities in the aforementioned domain. The special issue includes seven articles with topics ranging from data acquisition and data processing, to data modelling and applications. The experience in this special issue says that 3D building models should contain semantic information for various applications and therefore set the corresponding requirement in techniques and methods for 3D objects detection and modelling.","3D city model; 3D model; CityGML; Street image; Urban analysis","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care. Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-03-02","","","Digital Technologies","","",""
"uuid:0061d94c-46b6-4910-bb73-b6cdc9b85f84","http://resolver.tudelft.nl/uuid:0061d94c-46b6-4910-bb73-b6cdc9b85f84","Development and Testing of the CityJSON Energy Extension for Space Heating Demand Calculation","TUFAN, ÖZGE (TU Delft Architecture and the Built Environment)","León Sánchez, C.A. (mentor); Arroyo Ohori, G.A.K. (graduation committee); Ledoux, H. (graduation committee); Delft University of Technology (degree granting institution)","2022","3D city models are frequently used to acquire and store energy-related information of buildings to be used in energy applications, such as solar potential analyses and energy demand calculations. In this context, the most common data model is CityGML, which provides an application domain extension called the Energy ADE to store energy-related data in a systematic manner in XML format. On the other hand, CityJSON has been developed as a JSON-based encoding to exchange 3D city models, with the aim of eliminating the hierarchical structure and shortcomings of the XML-based CityGML. However, even though an extension mechanism exists in CityJSON, an energy-related CityJSON extension is not present in the current literature. Therefore, the aim of this thesis is to develop and test a CityJSON Energy Extension. To achieve this, the space heating demand calculation of buildings is chosen as the use case to validate and test the Extension.
In this thesis, a simplified version of the Energy ADE, called the Energy ADE KIT profile, is used as the first step to create a semi-direct translation to a CityJSON Energy Extension. After validating the Extension with the official validator of CityJSON, the space heating demand is calculated for a subset of the Rijssen-Holten in the Netherlands according to the Dutch standard NTA 8800. Required input data is collected from various data sources and stored in the CityJSON Energy Extension to test its usability for the use case. The Extension is then improved depending on the results of the tests based on the use case. The results show that the semi-direct translation lacked numerous objects and attributes to store certain input data, while the final version of the Extension fully supports the use case. Furthermore, while the semi-direct translation contained deep hierarchical structures, these were eliminated in the final Extension to comply with the design decisions behind CityJSON. The main differences between the Energy ADE and the CityJSON Energy Extension reflected this philosophy as well, where the former was built with a deep hierarchical structure, while the latter flattens this hierarchy by using the characteristics of JSON. In addition, a comparison in file sizes showed that the input 3D city model of the study area in CityJSON format had a file size of 40.6 MB, whereas the output CityJSON + Energy Extension file with all input and output data was 65.8 MB. It was discussed that this increase of 25.2 MB in file size is not significant, considering the high increase in the number of objects stored in the file. On the other hand, space heating demand calculation resulted in negative values for 32 buildings in the study area, which was not expected. While the possible reasons were detected, a solution could not be developed in the given time frame of the thesis. Overall, this thesis showed that the CityJSON Energy Extension can provide an easy-to-use alternative to CityGML Energy ADE, where the Extension files can be simply parsed by software and easily understood by the user without reaching large file sizes.
In this research a method is developed for combining detailed information from BIM models (IFC), with information about the surroundings from 3D City models (CityGML), and translating them to the ENVI-met format, so that these models can be used as input models for microclimate simulation in ENVI-met. This is done by creating a command line tool that extracts the necessary data from both input files, combining and converting it, and then writing it to a file in the ENVI-met format. Also guidelines and requirements for the input files will be established.
This is done by first establishing what information is necessary for microclimate simulation in ENVI-met and how this information needs to be represented, and then finding out where this information can be found in the intended input files, and how it is represented in there. From this can be concluded what information can be taken from which input file and the characteristics that are necessary for their correct use in the process can be established. Then the conversion tool itself can be developed, where the data is transformed to the same coordinate system and format, so that it can be combined and written to the ENVI-met format. In the last step the results are checked by doing a small case study and running the microclimate simulation.
This way, IFC and CityGML models can be used as input for microclimate simulation software ENVI-met, by using the conversion tool developed for this research and the provided guidelines.","IFC; CityGML; ENVI-met; Microclimate","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:89c73eee-93ab-488c-b6dc-4a853177f63f","http://resolver.tudelft.nl/uuid:89c73eee-93ab-488c-b6dc-4a853177f63f","Linking Semantic 3D City Models with Domain-Specific Simulation Tools for the Planning and Validation of Energy Applications at District Level","Widl, Edmund (AIT Austrian Institute of Technology); Agugiaro, G. (TU Delft Urban Data Science); Peters-Anders, Jan (AIT Austrian Institute of Technology)","","2021","Worldwide, cities are nowadays formulating their own sustainability goals, including ambitious targets related to the generation and consumption of energy. In order to support decision makers in reaching these goals, energy experts typically rely on simulation models of urban energy systems, which provide a cheap and efficient way to analyze potential solutions. The availability of high-quality, well-formatted and semantically structured data is a crucial prerequisite for such simulation-based assessments. Unfortunately, best practices for data modelling are rarely utilized in the context of energy-related simulations, so data management and data access often become tedious and cumbersome tasks. However, with the steady progress of digitalization, more and more spatial and semantic city data also become available and accessible. This paper addresses the challenge to represent these data in a way that ensures simulation tools can make use of them in an efficient and user-friendly way. Requirements for an effective linking of semantic 3D city models with domain-specific simulation tools are presented and discussed. Based on these requirements, a software prototype implementing the required functionality has been developed on top of the CityGML standard. This prototype has been applied to a simple yet realistic use case, which combines data from various sources to analyze the operating conditions of a gas network in a city district. The aim of the presented approach is to foster a stronger collaboration between experts for urban data modelling and energy simulations, based on a concrete proof-of-concept implementation that may serve as an inspiration for future developments.","3D city models; CityGML; Energy simulation software; Integrated energy systems; Urban energy modelling","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:7053dbba-a8f3-4233-b56d-91be967301e4","http://resolver.tudelft.nl/uuid:7053dbba-a8f3-4233-b56d-91be967301e4","Testing the new 3D bag dataset for energy demand estimation of residential buildings","León Sánchez, C.A. (TU Delft Urban Data Science); Giannelli, D. (TU Delft Urban Data Science); Agugiaro, G. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2021","The 3D BAG v. 2.0 dataset has been recently released: it is a country-wide dataset containing all buildings in the Netherlands, modelled in multiple LoDs (LoD1.2, LoD1.3 and LoD2.2). In particular, the LoD2.2 allows differentiating between different thematic surfaces composing the building envelope. This paper describes the first steps to test and use the 3D BAG 2.0 to perform energy simulations and characterise the energy performance of the building stock. Two well-known energy simulation software packages have been tested: SimStadt and CitySim Pro. Particular care has been paid to generate a suitable, valid CityGML test dataset, located in the municipality of Rijssen-Holten in the central-eastern part of the Netherlands, that has been then used to test the energy simulation tools. Results from the simulation tools have been then stored into the 3D City Database, additionally extended to deal with the CityGML Energy ADE. The whole workflow has been checked in order to guarantee a lossless dataflow. The paper reports on the proposed workflow, the issues encountered, some solutions implemented, and what the next steps will be.","3D BAG; 3D city database; CityGML; CitySim; Energy ADE; SimStadt","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:4dbdf83f-a149-4405-ab3a-4850d3ad45fe","http://resolver.tudelft.nl/uuid:4dbdf83f-a149-4405-ab3a-4850d3ad45fe","Volume comparison of automatically reconstructed multi-lod building models for urban planning applications","Doan, Truc Quynh (Student TU Delft); León Sánchez, C.A. (TU Delft Urban Data Science); Peters, R.Y. (TU Delft Urban Data Science); Agugiaro, G. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2021","3D city models are playing a growing role worldwide as sources of integrated information upon which different urban applications are developed. In the context of urban planning and design, semantic 3D city models can provide plenty of qualitative and quantitative information about the urban context and of the area(s) to be transformed. This paper takes inspiration and continues a work recently published in which several design parameters and Key Performance Indicators are computed from a semantic 3D city model, and later used in a GIS-supported urban design process to develop a new area. As many of such parameters are derived from the gross volume of the building stock, this paper investigates whether and to which extent different building stock models might affect the estimation of the gross volume. The study is carried out in anticipation of the upcoming LoD2-based, country-wide model of the Netherlands that is being finalised by our team. At the same time, the paper investigates whether and which information can be obtained regarding the quality of the LoD2 model from a comparison with the LoD1 one, with a focus on volume calculation.","3D BAG; CityGML; LoD comparison; LoD2 reconstruction; Urban planning","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:670973e9-afba-4359-9459-0cbdadf3b4d2","http://resolver.tudelft.nl/uuid:670973e9-afba-4359-9459-0cbdadf3b4d2","Ontology-based data mapping to support planning in historical urban centres","Colucci, E. (Politecnico di Torino); Kokla, M. (National Technical University of Athens); Noardo, F. (TU Delft Urban Data Science)","","2021","Because of the need for new sustainable future alternatives, the re-inhabitation of rural areas, hinterlands, small historical urban centres and villages has become a unique real opportunity. Therefore, it is necessary to define and adopt new sustainable urban planning and building permits to follow this path. These processes involve both various actors and disciplines and a variety of spatial and semantic data. For this reason, the present research aims at providing a methodology to build the necessary spatial documentation of historical centres and villages by adopting an ontology-based workflow. Existing ontologies and conceptualisations have been considered together with classes and rules from city historical core regulations. A case study has been selected considering its available spatial datasets and national data models. The bottom-up approach here adopted aims at validating and enriching a reference ontology previously developed in the domain of historical centre by adding new concepts and relations from selected regulation plans and other existing ontologies and data models. Finally, the obtained ontology is also populated with instances of concepts and relations.","CityGML; Historical Core Regulation; Historical Urban Centres; Semantic Definition; Spatial Datasets; Spatial Ontology; Urban Mapping; Villages","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:a7f7f0c8-7a34-454e-973a-d55f5b8b0dfe","http://resolver.tudelft.nl/uuid:a7f7f0c8-7a34-454e-973a-d55f5b8b0dfe","An integrative workflow for 3D city model versioning","Mastorakis, Konstantinos (TU Delft Architecture and the Built Environment)","Ledoux, H. (mentor); Vitalis, S. (mentor); Agugiaro, G. (graduation committee); Daamen, T.A. (graduation committee); Delft University of Technology (degree granting institution)","2020","3D city models are continuously becoming more popular among practitioners due to the volume and versatility of information they contain, which makes them suitable to be used in various applications. However, there is no mechanism to allow maintaining them updated at the same pace that cities evolve, or when error correction is necessary, eventually diminishing their value. Many cities around the world already possess such models which are mostly used for experimentation and research purposes. Such an example is also the city of Rotterdam, whose 3D city model is not regularly updated and has to be outsourced for that purpose. This thesis investigates into addressing this issue by proposing and implementing an integrative maintenance workflow. The workflow is designed to fulfill what the maintenance needs of a typical municipality are expected to be. Those needs were identified after conducting an analysis of the current situation and collecting information from practitioners within the municipality through interviews. The workflow is a combination of 3D city model versioning and visual editing capabilities with the aim to effectively maintain CityJSON encoded models in an intuitive way. Its implementation includes two prototype software implementations: a versioning component, which is utilized to create a workflow inspired by git flow and allows concurrent maintenance and alternative scenario testing in a non-linear and distributed way, and a visual editing component capable of editing CityJSON encoded 3D city models by extending Blender’s functionality. Following the implementation, the workflow was tested by simulating real world maintenance scenarios. The tests demonstrate the feasibility of maintaining 3D city models with such a workflow and more specifically the suitability of git based workflows. At the same time some key parameters of the versioning mechanism are identified which if tuned properly they can optimize the performance, behavior and robustness of 3D city model versioning. With both components being prototype solutions the workflow is far from operational and there is certainly a lot of space for improvement regarding both components. Utilizing the workflow in practice would be the ideal way for collecting useful feedback. Besides that, there are already extensions of Blender that combined with the visual updating component of the workflow can offer advanced integration of editing and analysis capabilities.","3D city model; Workflow; CityJSON; CityGML; git; Blender; rotterdam; versioning; Up3date","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:47218911-c93d-4295-a3de-231d023c1743","http://resolver.tudelft.nl/uuid:47218911-c93d-4295-a3de-231d023c1743","Modelling and managing massive 3D data of the built environment","Kumar, Kavisha (TU Delft Urban Data Science)","Stoter, J.E. (promotor); Ledoux, H. (promotor); Delft University of Technology (degree granting institution)","2020","A 3D city model is a digital representation of the spatial features in an urban
environment. Buildings, terrain, vegetation, water bodies, etc. all form an integral part of a 3D city model. The possibility to enrich these city models with additional application-specific information, whether new semantics or geometry, further increases their usability. However, in practice, the applications of 3D city models are mainly focused on buildings. The majority of standards available for representing 3D city models, such as IFC and CityGML, have well-defined specifications for modelling buildings, but often none for other city features. In addition, there are several other issues associated with the development and use of 3D city models of large cities, such as massive size of 3D city models, interoperability issues for 3D data from heterogeneous sources, harmonisation of different 3D standards, etc.
In this thesis, I investigate how to better model these massive and semantically
enriched 3D city models, and I focus on their use in different applications. I make five contributions. First, I explain how CityGML, the international standard for semantic 3D city modelling, is not efficient for storing massive TIN terrains, and present an improved solution to compactly store massive terrains in CityGML. Second, I describe how to model terrains at different LODs in CityGML, since the current CityGML data model lacks the specifications for modelling different terrain LODs at geometric and semantic level. Third, I explain how CityGML lacks precise specifications for modelling metadata of 3D city models and present an ISO 19115 compliant solution to add metadata. Fourth, I describe in this thesis how the development of the new standards LandInfra and InfraGML and their integration with the existing popular standards (IFC and CityGML) can
contribute to the BIM and 3D GIS interoperability and bring the two domains to a common footing. Fifth, I demonstrate my approach for the development of a harmonised semantic 3D city model based on CityGML for use in urban noise simulations. In addition, I have developed open source prototypes to help practitioners with the use of 3D city models. In this way, I also contribute to the open source community for 3D city modelling.
The thesis proposes additional research for future work. For example, since this research focuses specifically on the LODs of terrain models, it would be worthwhile to extend the research to explore the LOD concept for other urban features such as vegetation and landuse. Furthermore, LandInfra is a relatively young standard with low community support. This too requires more attention. Tools such as parsers, validators, visualisers, DBMS support, APIs, and so on are still lacking for LandInfra (and InfraGML). It would be interesting to see how the standards evolve and whether it can be applied in practice when such support is available. Interoperability of LandInfra with IFC and other standards is also an area that requires further investigation.","3D city models; CityGML; ADE; LandInfra; metadata","en","doctoral thesis","","978-94-6366-316-8","","","","","","","","","Urban Data Science","","",""
"uuid:fb35db7c-9af8-488c-8d0b-263b138d8fd3","http://resolver.tudelft.nl/uuid:fb35db7c-9af8-488c-8d0b-263b138d8fd3","Using CityGML EnergyADE Data in Honeybee","Wang, Xin (TU Delft Architecture and the Built Environment)","Agugiaro, G. (mentor); Stoter, J.E. (graduation committee); Delft University of Technology (degree granting institution)","2020","Urban energy simulation is becoming more and more important in various areas like urban planning, architecture design and city management. It provides quantified insights for architects and governors to deliver energy-efficient approaches. There are already quite a few energy simulation software or engines on the market. Among these tools, Ladybug family, a series of open-source python packages have its advantages: easy to use, high level of customization and low cost of adoption. It could be run in Rhino Grasshopper, a visual programming interface widely used by architecture industry. Taking 3D geometry created in Rhino and local weather data, Ladybug tools (Ladybug and Honeybee) prepare simulation recipes to run energy simulation with validated software engines like EnergyPlus and OpenStudio. With all these advantages, when using Ladybug and Honeybee for urban energy simulation, there are two major flaws: it is tedious to build 3D models of all building blocks in Rhino one by one and many key parameters required by energy simulation have to be entered manually. This geometry creation and parameters entering process could be avoided when using CityGML data as input, as CityGML with EnergyADE data already has 3D geometry and energy-related attributes of city within its data model. In this research, a mapping table between required simulation parameters of Ladybug tool - Honeybee and CityGML with EnergyADE data model is created. Based on this mapping relationship, by following a database approach, all information stored in CityGML with EnergyADE data is retrieved and stored in tables of 3DCityDB and later queried in Rhino Grasshopper and used in data mapping and processing workflow. Energy simulation results could be saved back to database too. It is concluded that using CityGML with EnergyADE data as input for Honeybee tools is applicable as there is a sufficient mapping relationship between their data models. However, as Honeybee has certain restrictions on input geometry (shared surface areas should be independent surfaces and surfaces should be convex etc.) and it runs energy simulation of buildings not simultaneously but one by one, it is not efficient to use Honeybee for large scale urban energy simulation.","CityGML; Urban Energy Simulation; Ladybug; Honeybee","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:969fa405-8098-43d2-adaf-34a52e428e8a","http://resolver.tudelft.nl/uuid:969fa405-8098-43d2-adaf-34a52e428e8a","The City of Tomorrow from... the Data of Today","Agugiaro, G. (TU Delft Urban Data Science); Garcia Gonzalez, F.G. (Student TU Delft); Cavallo, R. (TU Delft Theory, Territories & Transitions)","","2020","In urban planning, a common unit of measure for housing density is the number of households per hectare. However, the actual size of the physical space occupied by a household, i.e., a dwelling, is seldom considered, neither in 2D nor in 3D. This article proposes a methodology to estimate the average size of a dwelling in existing urban areas from available open data, and to use it as one of the design parameters for new urban-development projects. The proposed unit of measure, called “living space”, includes outdoor and indoor spaces. The idea is to quantitatively analyze the city of today to help design the city of tomorrow. First, the “typical”-dwelling size and a series of Key Performance Indicators are computed for all neighborhoods from a semantic 3D city model and other spatial and non-spatial datasets. A limited number of neighborhoods is selected based on their similarities with the envisioned development plan. The size of the living space of the selected neighborhoods is successively used as a design parameter to support the computer-assisted generation of several design proposals. Each proposal can be exported, shared, and visualized online. As a test case, a to-be-planned neighborhood in Amsterdam, called “Sloterdijk One”, has been chosen","CityGML; Grasshopper; Living space; Parametric design; Urban planning; Virtual city models","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:56fae074-3838-410e-89b5-6dbe8397d891","http://resolver.tudelft.nl/uuid:56fae074-3838-410e-89b5-6dbe8397d891","Tools for BIM-GIS Integration (IFC Georeferencing and Conversions): Results from the GeoBIM Benchmark 2019","Noardo, F. (TU Delft Urban Data Science); Harrie, Lars (Lund University); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Biljecki, F. (National University of Singapore); Ellul, Claire (University College London (UCL)); Krijnen, T.F. (TU Delft Urban Data Science); Eriksson, Helen (Lund University); Guler, Dogus (Istanbul Technical University); Hintz, Dean (Safe Software); Stoter, J.E. (TU Delft Urban Data Science)","","2020","The integration of 3D city models with Building Information Models (BIM), coined as GeoBIM, facilitates improved data support to several applications, e.g., 3D map updates, building permits issuing, detailed city analysis, infrastructure design, context-based building design, to name a few. To solve the integration, several issues need to be tackled and solved, i.e., harmonization of features, interoperability, format conversions, integration of procedures. The GeoBIM benchmark 2019, funded by ISPRS and EuroSDR, evaluated the state of implementation of tools addressing some of those issues. In particular, in the part of the benchmark described in this paper, the application of georeferencing to Industry Foundation Classes (IFC) models and making consistent conversions between 3D city models and BIM are investigated, considering the OGC CityGML and buildingSMART IFC as reference standards. In the benchmark, sample datasets in the two reference standards were provided. External volunteers were asked to describe and test georeferencing procedures for IFC models and conversion tools between CityGML and IFC. From the analysis of the delivered answers and processed datasets, it was possible to notice that while there are tools and procedures available to support georeferencing and data conversion, comprehensive definition of the requirements, clear rules to perform such two tasks, as well as solid technological solutions implementing them, are still lacking in functionalities. Those specific issues can be a sensible starting point for planning the next GeoBIM integration agendas","3D city models; Building Information Models; CityGML; Conversions; Georeferencing; Industry Foundation Classes; Interoperability; Standards","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:676ea45f-f0f3-4bd0-8c4e-a8ef75d729b0","http://resolver.tudelft.nl/uuid:676ea45f-f0f3-4bd0-8c4e-a8ef75d729b0","THE ISPRS-EUROSDR GEOBIM BENCHMARK 2019","Noardo, F. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Biljecki, F. (National University of Singapore); Ellul, C. (University College London (UCL)); Harrie, L. (Lund University); Krijnen, T.F. (TU Delft Urban Data Science); Kokla, M. (National Technical University of Athens); Stoter, J.E. (TU Delft Urban Data Science)","","2020","Standardised data formats and data models are essential for data integration and interoperability, which in turn adds value to data by allowing its reuse in multiple contexts. For this reason, in recent years extensive efforts have been focused on standards development. When representing the built environment, 3D city models and Building Information Models are particularly relevant, and their integration is now required to underpin use cases that cover the full life-cycle of a built asset, including design and planning as well as operations and management, and to support legal applications such as cadastral systems. For those kinds of data, CityGML by the Open Geospatial Consortium and Industry Foundation Classes by buildingSMART are the most popular reference standards. However, many users report, often through informal channels, the difficulties of working with these formats. This paper summarizes the outcomes of the GeoBIM Benchmark 2019, a scientific initiative funded by ISPRS and EuroSDR to collect insights into the most relevant issues encountered in the management of CityGML and IFC within existing software. Alongside data management (import, visualisation, analysis, export) problems, issues of particular consequence in terms of integration relate to georeferencing IFC files and the conversions among the two kinds of formats and models. Thus, the benchmark was designed to explore these tasks in available software. Following analysis of the benchmark results, a key outcome is the impossibility to find clear patterns in the behaviour of tools, which consequently means there is no consistency in the implementation of standards. Although the results could seem disappointing, the criticality in managing these standards as they are was described and this awareness can be the starting point for further research or further standards development. Finally, this project was useful to gather a wide community around this topic, and the discussion about the GeoBIM-related issues was definitely pushed.","3D city models; BIM; CityGML; GeoBIM; Industry Foundation Classes; interoperability","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:56859c0f-7c17-4fea-b232-06dba67669b0","http://resolver.tudelft.nl/uuid:56859c0f-7c17-4fea-b232-06dba67669b0","3D city models for urban mining: Point cloud based semantic enrichment for spectral variation identification in hyperspectral imagery","Ruben, P.A. (TU Delft Building Physics); Sileryte, R. (TU Delft Environmental Technology and Design); Agugiaro, G. (TU Delft Urban Data Science)","","2020","Urban mining aims at reusing building materials enclosed in our cities. Therefore, it requires accurate information on the availability of these materials for each separate building. While recent publications have demonstrated that such information can be obtained using machine learning and data fusion techniques applied to hyperspectral imagery, challenges still persist. One of these is the so-called 'salt-And-pepper noise', i.e.The oversensitivity to the presence of several materials within one pixel (e.g. chimneys, roof windows). For the specific case of identifying roof materials, this research demonstrates the potential of 3D city models to identify and filter out such unreliable pixels beforehand. As, from a geometrical point of view, most available 3D city models are too generalized for this purpose (e.g. in CityGML Level of Detail 2), semantic enrichment using a point cloud is proposed to compensate missing details. So-called deviations are mapped onto a 3D building model by comparing it with a point cloud. Seeded region growing approach based on distance and orientation features is used for the comparison. Further, the results of a validation carried out for parts of Rotterdam and resulting in KHAT values as high as 0.7 are discussed.","CityGML; Enrichment; Point cloud; Semantic 3D city models; Urban mining","en","journal article","","","","","","","","","","","Environmental Technology and Design","","",""
"uuid:466ee21f-3386-4813-8f45-5687d30416c1","http://resolver.tudelft.nl/uuid:466ee21f-3386-4813-8f45-5687d30416c1","Data modeling for operation and maintenance of utility networks: Implementation and testing","Fossatti, F. (University of Twente); Agugiaro, G. (TU Delft Urban Data Science); Olde Scholtenhuis, L. (University of Twente); Dorée, A. (University of Twente)","","2020","The organisational data models that support the information needs of utility network managers are proprietary and domain-specific, while the emerging national standards in this field often lack lifecycle data representation capabilities. However, multiple types of utility networks can be comprehensively represented with the free and open-source Utility Network Application Domain Extension (ADE) of the international standard CityGML. The Operation & Maintenance (O&M) Domain Ontology is a proposed extended version of the Utility Network ADE that allows for consistent and comprehensive processing, storage and exchange of O&M-related utility network data. So far, this ontology has not yet been implemented in a spatial-relational database. Consequently, the support it offers during routine utility asset management tasks has remained untested. This paper, therefore, tests the support of the O&M domain ontology for asset management and proposes a database implementation of this data model. To this end, it models and loads two utility networks from the campus of the University of Twente, the Netherlands. It tests the ontology's support for asset management by simulating a street reconstruction project and retrieving necessary project information in relation to a utility's (a) maintenance history and performance, and (b) site conditions and valve locations. Results show that the implemented model supports projects with rapid, comprehensive, and consistent information about semantic details of utilities. Such data needs yet to be collected and registered systematically to enable future data-driven asset management practices.","Utility Networks; CityGML; Utility Network ADE; Operation & Maintenance","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:fc98b627-a64f-46cc-a5ab-7d7eed56401b","http://resolver.tudelft.nl/uuid:fc98b627-a64f-46cc-a5ab-7d7eed56401b","Automatic conversion of CityGML to IFC","Salheb, N. (Student TU Delft); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2020","The trend of increased usage of both BIM and 3D GIS and the similarity between the two has led to an increase in the overlap between them. A key application of such overlap is providing geospatial context data for BIM models through importing 3D GIS-data to BIM software to help in different design-related issues. However, this is currently difficult because of the lack of support in BIM software for the formats and data models of 3D Geo-information. This paper deals with this issue by developing and implementing a methodology to convert the common open 3D city model data model into the most common open BIM data format, namely CityGML (Gröger et al., 2012) to IFC (buildingsmart, 2019b). For the aim of this study, the two standards are divided into 5 comparable subparts: Semantics, Geometry, Geographical coordinates, Topology, and Encoding. The characteristics of each of these subparts are studied and a conversion method is proposed for each of them from the former standard to the latter. This is done by performing a semantic and geometrical mapping between the two standards, converting the georeferencing from global to local, converting the encoding that the two standards use from XML to STEP, and deciding which topological relations are to be retained. A prototype implementation has been created using Python to combine the above tasks. The work presented in this paper can provide a foundation for future work in converting CityGML to IFC. It provides an insight into the relationship between the two standards and a methodology for the conversion from one to the other, and the process of developing software to perform such conversion. This is done in a way that can be extended for future specific needs.","CityGML; IFC; Conversion; GeoBIM","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:cddfb27e-f1e5-4c6f-8944-21e6d416398a","http://resolver.tudelft.nl/uuid:cddfb27e-f1e5-4c6f-8944-21e6d416398a","The Eurosdr Geobim Project: developing case studies for the use of geobim in practice","Ellul, C. (University College London (UCL)); Noardo, F. (TU Delft Urban Data Science); Harrie, L. (Lund University); Stoter, J.E. (TU Delft Urban Data Science)","","2020","Although the use of location-based data (location coupled with semantic information) within Geographical Information Systems (GIS) and from Earth Observation (e.g. satellite) sources has been long established for decision makers, this has only recently been reflected in the construction sector with a more recent move from Computer Aided Design (CAD) to Building Information Modelling. BIM has opened up an additional source of valuable location-based data, with particular focus on the architecture, structural and engineering detail of both buildings and infrastructure projects. As with most if not all location data, while BIM can be used on its own, major benefits are to be derived from integration with other data sources. When this is done with GIS, the result is known as GeoBIM and although there are some similarities between the two, challenges to integration are both technical and non technical, in particular the need for clear case studies to motivate both developers and senior management. There are synergies to be gained from a multi-national, coordinated approach when addressing these challenges, where participants can benefit from each-others' experience and where the needs of users and the National Mapping and Cadastral Agency (NMCA) perspective underpin the research. This paper summarises final outcomes and findings of the EuroSDR GeoBIM research project, which was set up to provide the required multi-national, user-centric collaborative framework, which had as its overall aim the development of best practice guidelines for GeoBIM, and due to its situation within EuroSDR has an NMCA focus. The paper updates information with regard to GeoBIM projects and maturity in the participant countries, and provides an overview of the two case studies developed.","GeoBIM; ndustry Foundation Classes; CityGML; interoperability; BIM; 3D City models","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:9585f9e1-5f87-4baf-aa38-2e651caeb9ea","http://resolver.tudelft.nl/uuid:9585f9e1-5f87-4baf-aa38-2e651caeb9ea","Reference study of CityGML software support: The GeoBIM benchmark 2019—Part II","Noardo, F. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Biljecki, Filip (National University of Singapore); Ellul, Claire (University College London (UCL)); Harrie, Lars (Lund University); Krijnen, T.F. (TU Delft Urban Data Science); van Liempt, J.N.H. (TU Delft Urban Data Science); Vitalis, S. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2020","OGC CityGML is an open standard for 3D city models intended to foster interoperability and support various applications. However, through our practical experience and discussions with practitioners, we have noticed several problems related to the implementation of the standard and the use of standardized data. Nevertheless, a systematic investigation of these issues has never been carried out, and there is thus insufficient evidence for tackling the problems. The GeoBIM benchmark project is aimed at finding such evidence by involving external volunteers, reporting on various aspects of the behavior of tools (geometry, semantics, georeferencing, functionalities), analyzed and described in this article. This study explicitly pointed out the critical points embedded in the format as an evidence base for future development. A companion article (Part I) describes the results of the benchmark related to IFC, the counterpart of CityGML within building information modeling.","3D city models; CityGML; data models; GeoBIM; interoperability; software support; standards","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:18df757e-e803-4f6c-8b91-acec76a7bf4f","http://resolver.tudelft.nl/uuid:18df757e-e803-4f6c-8b91-acec76a7bf4f","Flood damage cost estimation in 3D based on an indicator modelling framework","Elfouly, Mostafa (Technische Universität München); Labetski, A. (TU Delft Urban Data Science)","","2020","Flooding and other natural disasters pose risks to cities and residential homes, and these are set to increase in the face of climate change. Single-family residential buildings are of particular interest because they are difficult to insure and often highlight wealth discrepancies in society in the wake of natural disasters. Calculating building replacement cost based on a specific natural disaster is of interest to municipalities and city planners who are working to prepare their cities for potential future costs of recovery. There are models designed by flood modellers, and there are models designed by city planners. This paper presents a novel Indicator Modelling Framework (IMF) by bringing together a model from the flooding domain (HAZUS) and a model from the geospatial application domain (e.g. CityGML) and weaving them together. The weaving process automatically calculates the building replacement cost for buildings based on a flood scenario as well as generates domain-specific metadata. The weaving process capitalizes on the strengths of both models, and future work will focus on weaving between models in other domains.","CityGML; General Indicator Model; Indicator Modelling Framework; flood modelling; metadata; model-driven engineering","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:03ab695a-dc68-403a-b934-c810f087df42","http://resolver.tudelft.nl/uuid:03ab695a-dc68-403a-b934-c810f087df42","The use of digital models in microclimatic studies : First steps in coupling CityGML with ENVI-met","Arapakis, Takis (TU Delft Architecture and the Built Environment)","Agugiaro, Giorgio (mentor); Maiullari, Daniela (graduation committee); Delft University of Technology (degree granting institution)","2019","In recent years, the need to reduce the global warming of the planet has become more imperative than ever. Global warming and, at local scale, Urban Heat Island phenomena are among the primary effects of the increased building carbon emissions. Nevertheless, understanding and controlling the parameters which intensify, or mitigate, the increasing in temperatures in the surroundings of a building are pivotal, as sustainable design can significantly reduce the buildings’ energy demand. Micro-climate simulations can provide more accurate input for building energy simulations since they can accurately simulate the interactions between those parameters to calculate detailed weather data. Despite the increasing knowledge about the significance of the microclimate, energy simulation users still rely on derived, or interpolated weather data from sparsely located weather stations, located generally outside the urban environment. The reason behind this commonly adopted approach is that the generation of microclimate data is costly in terms of time, and currently standards for storing this generated data have not been developed. ENVI-met is a microclimatic simulation software that requires a model of an urban area and weather parameters on its boundaries to generate a large extent of data like air, temperature, relative humidity, wind speed etc. Constructing this model manually contains a number of significant limitations, such as high design cost in time and need for data collection from different sources – thus the chance of design errors is high. In this thesis a novel approach is introduced where the ENVI-met software is used for microclimatic simulations at district scale. However, the input model in this case is created by data extracted from a CityGML-based 3D city model. In addition, the generated microclimatic data is stored back to CityGML, where it can be re-used. The proposed methodology is implemented via a Graphics User Interface, divided in two main phases, serving the required bi-directional data flow. It was designed and implemented based on the following specifications: i) the user involvement in the whole process needs to be minimum, ii) the interface should create simulation-ready input models of various resolutions and iii) it must work with different CityGML datasets.
A data requirement analysis indicated that a CityGML-based city model can feed its data to ENVI-met by the interface, so that the input model required by ENVI-met can be constructed fully automatically. In return, the storage of the generated results data is also possible. Therefore, an automated data flow between a CityGML-based city model and ENVI-met can be achieved, offering the following advantages: i) the ENVI-met input model can be constructed fast and automatically and ii) ENVI-met outputs can be translated to real world coordinates – thus can be visualized and processed in GIS software and ultimately stored back into the CityGML-based 3d city model.","CityGML; ENVI-met; Coupling; Microclimate","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:455b6060-5152-46eb-8c64-5382f915442b","http://resolver.tudelft.nl/uuid:455b6060-5152-46eb-8c64-5382f915442b","Automatic Conversion of CityGML to IFC","Salheb, Nebras (TU Delft Architecture and the Built Environment)","Stoter, Jantien (mentor); Arroyo Ohori, Ken (graduation committee); Boelhouwer, Michiel (graduation committee); Delft University of Technology (degree granting institution)","2019","This study presents a methodology to convert from the most dominant 3D city model standard in 3D GIS to BIM. Namely, CityGML to IFC. IFC is chosen because it is the common open standard to exchange data in the BIM world. For the aim of this study, the two standards are divided into 5 comparable sub-parts; Semantics, Geometry, Geographical coordinates, Topology, and Encoding. The characteristics of each of these sub-parts are studied and a theoretical conversion method is proposed for it from the first standard to the other. This is done by performing a semantic and geometrical mapping between the two standards, converting the georeferencing from Global to local, converting the encoding that the two standards use from XML to STEP, deciding which topological relations are to be retained, and providing a basic implementation that is created using Python to combine the above tasks. The work presented in this thesis can provide a foundation for future work in converting CityGML to IFC. It provides an insight into the relationship between the two standards and a methodology for the conversion from one to the other, and the process of developing software to perform such conversion. This is done in a way that can be extended for future specific needs.","BIM; CityGML; IFC; Conversion; Geomatics","en","master thesis","","","","","","","","","","","","Geomatics","","52.006193, 4.371070"
"uuid:ebfc48f8-4704-47d3-9654-cd00c765e0af","http://resolver.tudelft.nl/uuid:ebfc48f8-4704-47d3-9654-cd00c765e0af","Modelling different levels of detail of roads and intersections in 3D city models","Boersma, Freek (TU Delft Architecture and the Built Environment; TU Delft Urbanism)","Labetski, Anna (mentor); Stoter, Jantien (graduation committee); Delft University of Technology (degree granting institution)","2019","In the last two decades there has been a steady rise in the gathering and use of 3D geo-information. A common way to store and use 3D data is by using 3D city models. In 3D city models, geo-information can be stored at different levels of detail. CityGML, the most commonly used data model and encoding for 3D city models, uses five levels of detail in order to model increasing geometric and semantic complexity. These levels of detail may be interpreted as a model quality measure, and as a guideline for users that need data for a certain application. CityGML consists of several thematic modules, each with their own level of detail specification. Some of these modules have a more further developed level of detail specification than others. Recently, several authors have proposed improvements to the Transportation module. This has led to proposals for various changes, especially concerning road data. However, these proposed changes have not been encoded yet. The main critiques are the lack of a level of detail specification for linear representations of roads, no ability to model networks, no representation of intersections and general ambiguity in the level of detail specification. Many road data use cases might potentially benefit from improvements on these points. In this thesis I attempt to improve the current level of detail specification of roads in the CityGML data model. The improvements are encoded in CityJSON, a JSON encoding of this data model. I assess the shortcomings in the current CityGML transportation module. After, a road data needs analysis is performed on three use cases: transport modelling, navigation and road maintenance. The data needs are compared to modelling approaches of other road data standards. This has resulted in several encoded improvements. A topological structure has been added to CityJSON. This includes the addition of two new modelling classes: Nodes and Edges. This structure is general such that it can be used by other thematic modules as well. Moreover, the level of detail specification for roads has been further developed to include both the linear representations and less ambiguous areal representations. This includes a prescription on how to model intersections and roundabouts at different levels of detail. Finally, I provide a structure which enables one to link the linear and areal road data together. This link is made at the scale level of the object, which data providers may choose themselves. This way one object can be modelled in two representation types without needing a one-to-one mapping between linear road segments and areal triangulated surfaces. These concepts are then tested by creating a CityJSON road data file for all new levels of detail.","3D city model; Roads; Intersections; CityGML; CityJSON","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:0fd2ffec-f25a-4391-be68-e816cc2611dd","http://resolver.tudelft.nl/uuid:0fd2ffec-f25a-4391-be68-e816cc2611dd","3D City Models in the Context of Urban Mining: A case study based on the CityGML model of Rotterdam","Ruben, Pablo (TU Delft Architecture and the Built Environment; TU Delft Applied Sciences)","Ŝileryté, R. (mentor); Agugiaro, G. (mentor); Zhou, K. (graduation committee); Delft University of Technology (degree granting institution)","2019","Recently, the application of machine learning and data fusion techniques on hyperspectral imagery have demonstrated potential for ground cover classification at material level. Hereby, specific locations of resources enclosed in cities (e.g. roof materials) can be identified, which is critically relevant within the field of urban mining. A limitation of this approach is the so-called 'pepper and salt effect', the oversensitivity of the classifiers to spectral variations within a pixel (e.g. chimneys, roof windows). Identifying and correcting affected pixels can be done statistically (e.g. using a majority filter), but not in cases where spectral variations affect a majority of pixels characterizing a surface. A solution to this limitation would be the usage of 3D city models containing the objects inducing the spectral variations. However, such highly detailed 3D city models are often unavailable as they cannot be produced automatically yet. An alternative covered by this research is to use a less detailed 3D city model and semantically enrich it with the required data. As 3D city models are usually produced using a point cloud, such a point cloud is used to perform the enrichment. The main research question addressed is therefore: How can a CityGML LOD2 model be semantically enriched in order to improve material classification performed on roof surfaces?. To address this, an existing LOD2 model was compared to a point cloud acquired by Ligth Detecation and Ranging and 'deviation' points were identified. This identification uses a distance check for seed selection and performs a region growing with an orientation check. In a subsequent step, 'deviation' point regions were translated into a geometric shape by usage of their Voronoi diagram and fused with the pixels of hyperspectral imagery. Part of this research is also a nominal validation analyzing a total of 41 buildings and 831 pixels located in the south of Rotterdam (Netherlands). Overall kappa values of up to 0.7 and commission errors as low as 10% (for the class 'clean' pixels) were obtained, showing potential of the chosen method. Additionally, a rational validation was performed to assess the impact of potential tolerance of classifiers for 'spectral deviations'. This one only included 10 buildings, but took into account 328 pixels located up to 30% outside the roof surface A main outcome is the recommendation on settings to use depending on the specific user needs. To accurately quantify materials, relatively 'loose' settings are recommended. In contrast, to identify presence of materials, stricter settings are recommended. Beyond this, recommendations to data suppliers and potential applications of the method to other fields are formulated.","enrichment; CityGML; hyperspectral imagery; urban mining; Rotterdam; APEX; spectral variation filtering; semantics; LOD; level of detail; point cloud; AHN","en","master thesis","","","","","","","","","","","","Geomatics","","51.8870079, 4.463591"
"uuid:2a95e1ef-1cdb-4f33-8258-9d6f90b4adc7","http://resolver.tudelft.nl/uuid:2a95e1ef-1cdb-4f33-8258-9d6f90b4adc7","Harmonising the OGC Standards for the Built Environment: A CityGML Extension for LandInfra","Kumar, Kavisha (TU Delft Urban Data Science); Labetski, A. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2019","The relatively new Open Geospatial Consortium (OGC) standard LandInfra documents in its data model land and civil engineering infrastructure features. It has a Geography Markup Language (GML) implementation, OGC InfraGML, which has essentially no software support and is rarely used in practice. In order to share the benefits of LandInfra (and InfraGML) with a wider public, we have created the Infra Application Domain Extension (ADE), a CityGML ADE that allows us to store LandInfra features in CityGML. In this paper, we semantically map LandInfra to CityGML, describe our ADE, and discuss a few used cases where our ADE can be useful for applications for the built environment. We also provide software to automatically convert datasets from InfraGML to CityGML (and our ADE), and vice versa, as well as to validate them, which will help practitioners generate real-world InfraGML datasets.","Infra ADE; LandInfra; InfraGML; CityGML; GIS; 3D City models","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:635c07eb-2e25-402f-9ff1-92ab43fc319f","http://resolver.tudelft.nl/uuid:635c07eb-2e25-402f-9ff1-92ab43fc319f","CityJSON: a compact and easy-to-use encoding of the CityGML data model","Ledoux, H. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Kumar, Kavisha (TU Delft Urban Data Science); Dukai, B. (TU Delft Urban Data Science); Labetski, A. (TU Delft Urban Data Science); Vitalis, S. (TU Delft Urban Data Science)","","2019","The international standard CityGML is both a data model and an exchange format to store digital 3D models of cities. While the data model is used by several cities, companies, and governments, in this paper we argue that its XML-based exchange format has several drawbacks. These drawbacks mean that it is difficult for developers to implement parsers for CityGML, and that practitioners have, as a consequence, to convert their data to other formats if they want to exchange them with others. We present CityJSON, a new JSON-based exchange format for the CityGML data model (version 2.0.0). CityJSON was designed with programmers in mind, so that software and APIs supporting it can be quickly built. It was also designed to be compact (a compression factor of around six with real-world datasets), and to be friendly for web and mobile development. We argue that it is considerably easier to use than the CityGML format, both for reading and for creating datasets. We discuss in this paper the main features of CityJSON, briefly present the different software packages to parse/view/edit/create files (including one to automatically convert between the JSON and GML encodings), analyse how real-world datasets compare to those of CityGML, and we also introduce Extensions, which allow us to extend the core data model in a documented manner.","3D city modelling; CityGML; Data modelling","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:a32dcbc7-e4b6-4f62-9f92-551c8e88fef4","http://resolver.tudelft.nl/uuid:a32dcbc7-e4b6-4f62-9f92-551c8e88fef4","Incorporating topological representation in 3D City Models","Vitalis, S. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2019","3D city models are being extensively used in applications such as evacuation scenarios and energy consumption estimation. The main standard for 3D city models is the CityGML data model which can be encoded through the CityJSON data format. CityGML and CityJSON use polygonal modelling in order to represent geometries. True topological data structures have proven to be more computationally efficient for geometric analysis compared to polygonal modelling. In a previous study, we have introduced a method to topologically reconstruct CityGML models while maintaining the semantic information of the dataset, based solely on the combinatorial map (C-Map) data structure. As a result of the limitations of C-Map’s semantic representation mechanism, the resulting datasets could suffer either from semantic information loss or the redundant repetition of them. In this article, we propose a solution for a more efficient representation of geometry, topology and semantics by incorporating the C-Map data structure into the CityGML data model and implementing a CityJSON extension to encode the C-Map data. In addition, we provide an algorithm for the topological reconstruction of CityJSON datasets to append them according to this extension. Finally, we apply our methodology to three open datasets in order to validate our approach when applied to real-world data. Our results show that the proposed CityJSON extension can represent all geometric information of a city model in a lossless way, providing additional topological information for the objects of the model.","3D city model; topology; combinatorial map; linear cell complex; CityJSON; CityGML","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:fb908568-c569-4004-befc-06bf8b3b43c5","http://resolver.tudelft.nl/uuid:fb908568-c569-4004-befc-06bf8b3b43c5","GeoBIM benchmark 2019: Design and initial results","Noardo, F. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Biljecki, F. (National University of Singapore); Krijnen, Thomas (Eindhoven University of Technology); Ellul, Claire (University College London (UCL)); Harrie, Lars (Lund University); Stoter, J.E. (TU Delft Urban Data Science)","","2019","GeoBIM, the integration of 3D geoinformation (Geo) with building information models (BIM), is a subject of increasing attention in both domains. A well-known practical challenge for this integration is the mixed state of software support for open standards in each domain that would ease the integration. This is often known by practitioners but poorly documented. In order to solve this problem, we devised the GeoBIM benchmark, in which we compile the experiences of volunteering participants, who perform a guided study to test the software they are most familiar with against a few provided datasets structured in open standards. The aim of the tests is to improve the knowledge of the state of the art in the software support for GeoBIM open standards and to identify points for improvement. In this paper, we present the design of the benchmark, especially explaining and discussing the chosen data to be used with their connected issues to be tested, and some initial results.","GeoBIM; software support; interoperability; Open Standards; CityGML; IFC; 3D city models; BIM","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:825eddec-ae1b-42b6-a8f9-f4b7f00fbe24","http://resolver.tudelft.nl/uuid:825eddec-ae1b-42b6-a8f9-f4b7f00fbe24","The LandInfra standard and its role in solving the BIM-GIS quagmire","Kumar, Kavisha (TU Delft Urban Data Science); Labetski, A. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2019","LandInfra is a relatively new open standard for modelling and representing land and infrastructure features. As it overlaps with other open standards in BIM (IFC) and 3D GIS (CityGML), it has been recognised as a potential candidate to bridge the gap between the two domains. However, the knowledge of this standard in both communities is low, and there are still no publications which fully explore LandInfra and its possibilities for integrated BIM-GIS applications. In this paper, we review the LandInfra conceptual model and its GML encoding InfraGML, provide a detailed comparison of it with respect to CityGML and IFC, and investigate a few potential use cases where LandInfra and InfraGML are useful for BIM-GIS applications.","LandInfra; InfraGML; GIS; BIM; CityGML; IFC","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:25a5452b-b221-4975-886e-e46917fb0469","http://resolver.tudelft.nl/uuid:25a5452b-b221-4975-886e-e46917fb0469","An interactive design tool for urban planning using the size of the living space as unit of measurement","Garcia Gonzalez, Gabo (Student TU Delft); Agugiaro, G. (TU Delft Urban Data Science); Cavallo, R. (TU Delft Theory, Territories & Transitions)","","2019","In urban planning, a common unit of measurement for population density is the number of households per hectare. However, the actual size of the households is seldom considered, neither in 2D nor in 3D. This paper proposes a method to calculate the average size of the household in existing urban areas from available open data and to use it as a design parameter for new urban development. The proposed unit of measurement includes outdoor and indoor spaces, the latter comprising both residential and non-residential spaces. As a test case, a to-be-planned neighbourhood in Amsterdam, called Sloterdijk One, was chosen. First, the sizes of “typical” households, as well as a series of KPIs, were computed in existing neighbourhoods of Amsterdam, based on their similarities with the envisioned Sloterdijk One plan. Successively, the resulting size of the household was used as a design parameter in a custom-made tool to generate semi-automatically several design proposals for Sloterdijk One. Additionally, each proposal can be exported as a CityGML model and visualised using web-based virtual globes, too. Significant differences among the resulting proposals based on this new unit of measurement were encountered, meaning that the average size of a household plays indeed a major role.","urban planning; virtual city models; parametric design; CityGML; living space; interactive modelling; Living space; Urban planning; Interactive modelling; Virtual city models; Parametric design","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:c87aaa61-c56d-4314-bd77-ec9457d6d909","http://resolver.tudelft.nl/uuid:c87aaa61-c56d-4314-bd77-ec9457d6d909","A Data Structure to Incorporate Versioning in 3D City Models","Vitalis, S. (TU Delft Urban Data Science); Labetski, A. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2019","A 3D city model should be constantly updated with new versions, either to reflect the changes in its real-world counterpart, or to improve and correct parts of the model. However, the current standards for 3D city models do not support versioning, and existing version control systems do not work well with 3D city models. In this paper, we propose an approach to support versioning of 3D city models based on CityJSON and the concepts behind the Git version control system, including distributed and non-linear workflows. We demonstrate the benefits of our approach in two examples and in our software prototype, which is able to extract a given version of a 3D city model and to display its history.","3D City Models; CityGML; CityJSON; Git; Versioning","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:786d397d-aa2f-45b7-898a-5d7d13682b66","http://resolver.tudelft.nl/uuid:786d397d-aa2f-45b7-898a-5d7d13682b66","An Improved LOD Framework for the Terrains in 3D City Models","Kumar, Kavisha (TU Delft Urban Data Science); Labetski, A. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2019","The Level of Detail (LOD) concept in CityGML 2.0 is meant to differentiate the multiple representations of semantic 3D city models. Despite the popularity and general acceptance of the concept by the practitioners and stakeholders in 3D city modelling, there are still some limitations. While the CityGML LOD concept is well defined for buildings, bridges, tunnels, and to some extent for roads, there is no clear definition of LODs for terrain/relief, vegetation, land use, water bodies, and generic city objects in CityGML. In addition, extensive research has been done to refine the LOD concept of CityGML for buildings but little is known on requirements and possibilities to model city object types as terrain at different LODs. To address this gap, we focus in this paper on the terrain of a 3D city model and propose a framework for modelling terrains at different LODs in CityGML. As a proof of concept of our framework, we implemented a software prototype to generate terrain models with other city features integrated (e.g. buildings) at different LODs in CityGML.","3D city models; CityGML; LOD framework; Level of Detail; Terrain","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:59aee21d-a7f8-4a1b-8bdb-5beef3794233","http://resolver.tudelft.nl/uuid:59aee21d-a7f8-4a1b-8bdb-5beef3794233","GeoBIM Benchmark 2019: Intermediate Results","Noardo, F. (TU Delft Urban Data Science); Biljecki, F. (National University of Singapore); Agugiaro, G. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Ellul, Claire (University College London (UCL)); Harrie, Lars (Lund University); Stoter, J.E. (TU Delft Urban Data Science)","","2019","An investigation into the implementation state of open standards in software is currently ongoing through the ISPRS/EuroSDR ‘GeoBIM benchmark 2019’ initiative, which kicked off earlier this year. The benchmark activity provides a way of assessing and comparing the functionality of different software packages in GIS and BIM in terms of their ability to handle standardised data (IFC and CityGML) and undertake various tasks using this data. Approximately 65 people have registered to participate so far, with participants from a wide range of backgrounds and proposing to test a variety of software packages. This confirms that the issues under investigation are of interest, and also meets the wider benchmark aim of having a variety of participants, since the project is conceived as using a bottom-up approach with cross-disciplinary and cross-expertise participation. While full benchmark results are not due to be submitted until later this year, interim results have highlighted a number of common issues across multiple software packages, and a web meeting for participants held in July 2019 also led to some improvements in how the benchmark results are being captured.","3D city models; BIM; CityGML; Data interoperability; GeoBIM; IFC; Open standards; Software support","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:ee000f56-9262-402c-a0fb-9e190483cb20","http://resolver.tudelft.nl/uuid:ee000f56-9262-402c-a0fb-9e190483cb20","A metadata ADE for CityGML","Labetski, A. (TU Delft Urban Data Science); Kumar, Kavisha (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2018","While there exist international standards for geospatial metadata (ISO 19115), these are rarely used in practice for 3D datasets, and one of the OGC standards for 3D city models, CityGML, does not offer a mechanism to store metadata in a structured way. Having metadata in CityGML files, which are in practice often very large and complex, would provide us with the ability to quickly understand the nature of a dataset and to determine if it is relevant for a specific task. Alack of metadata introduces uncertainty into models that are already full of assumptions and estimations. In this paper, we first examine the metadata needs that are specific for 3D geographical datasets and propose ISO 19115compliant categories. We then describe how these can be used within CityGML by defining an Application DomainExtension (ADE), which allows us to store metadata for existing city objects of CityGML, as well as objects in other domain-specific ADEs. Our ADE, its schema in both UML and XSD, and sample datasets is openly accessible, and it can be easily extended to support application specific metadata. In addition the metadata elements have been added to the core of CityJSON. We also offer software to generate automatically many of the metadata categories and we propose coupling it with the source 3D dataset.","3D City Models; Metadata; CityGML; Application Domain Extension; UML; Automation","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:90460ed2-a9f0-4649-91a4-29ccb2c1c4f8","http://resolver.tudelft.nl/uuid:90460ed2-a9f0-4649-91a4-29ccb2c1c4f8","Contextualising Ontologies with Image, Number and Rationality","Soon, Kean Huat","","2018","Ontologies have been proven useful in areas such as information management and Artificial Intelligence. Based on ontologies, datasets using the same concepts can be integrated or converted automatically. The same concept however can represent different features depending upon perspectives. A concept “building” for instance can represent a physical building, a design building or a 3D building model and these “buildings” are related to one another based on certain logics. If one simply converts IFC to CityGML using the same concept “building” without considering the explicit representations and the logics the representations should relate, one may inappropriately use the resulted outputs as the models may have changed from design to physical and the changes involved in the life cycle are not made explicit. The paper demonstrates a framework to contextualise ontologies based on different perspectives from I Ching, Book of Change. The perspectives are Image (象), Number (数) and Rationality (理). Image refers to the explicit representation a concept represents; Number refers to the computational models in formats that computer systems are able to process and read. Rationality means the logics things should relate. In different perspectives, the same concept can be represented differently. As a case study, the paper illustrates how the framework can be applied in a previous research that integrates the legal space from the ePlan model and the physical space from the CityGML schema based on the LADM OWL ontology. From the different perspectives, the framework allows to check if the data is correctly integrated or converted to prevent information loss. Although the framework is conceptual, the next step is to formalise the ontologies to include the perspectives in a formal language like OWL.","I Ching; Ontologies; Building; ePlan; CityGML; LADM OWL","en","conference paper","","","","","","","","","","","","","",""
"uuid:f3db0e31-9650-4f14-aad1-2b7c4549275e","http://resolver.tudelft.nl/uuid:f3db0e31-9650-4f14-aad1-2b7c4549275e","A proposal for an improved transportation model in CityGML","Labetski, A. (TU Delft Urban Data Science); van Gerwen, Stefan (Provincie Noord Brabant); Tamminga, G.F. (TU Delft Transport and Planning); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","Arroyo Ohori, K. (editor); Labetski, A. (editor); Agugiaro, G. (editor); Koeva, M. (editor); Stoter, J (editor)","2018","CityGML, an OGC standard, is an open data model for virtual 3D city models and includes buildings, roads, terrain, water bodies, etc. While many modules are well-developed (eg buildings, bridges, tunnels), the transportation model is, based on our consultations with various government agencies and municipalities, not sufficient for most transportation applications. We propose in this paper several improvements to the CityGML v2. 0 Transportation module, and to the previous efforts for improving it. Our additions are based on the consultations we had, and on the use-cases that were identified. We argue that the following changes are necessary: A) multi-LoD modelling of roads, B) carriageway representation, C) detailed intersection modelling and, D) introducing waterways as a new sub-class.","3D city modelling; CityGML; road modelling; transportation; levels of detail; needs analysis","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"uuid:8b8967a8-0a0f-498f-9d37-71c6c3e532af","http://resolver.tudelft.nl/uuid:8b8967a8-0a0f-498f-9d37-71c6c3e532af","Urban Vegetation Modeling 3D Levels of Detail","Ortega-Córdova, Lessie (TU Delft Architecture and the Built Environment; TU Delft Urbanism)","Stoter, Jantien (mentor); Labetski, Anna (mentor); Delft University of Technology (degree granting institution)","2018","3D city models are now common planning and analysis tools. Urban vegetation as a feature in these models, however, is neglected overshadowed by the focus on buildings, so its inclusion in 3D city models is often symbolic. On the other hand, urban vegetation improves the comfort and social well being of a city’s inhabitants and is a resource for sustainable urban growth and an environmentally friendly resource for mitigating the negative effects of climate change, e.g., frequent heat waves, floods from storm downpours and extended dry periods. Trees also mitigate Urban Heat Island (UHI) effects. Urban vegetation’s ecosystem services (ecoservices) as mitigation functions of pollution and negative effects of climate change have propelled research, studies, applications, and simulations that need data and 3D models of existing vegetation e.g., for spatial simulations, to assess the canopy cooling impact to surroundings or to identify areas prone to UHI. In view of these needs, urban vegetation in 3D city models is underrepresented. Guidelines for modelling vegetation are already provided in CityGML, the 3D city modelling standard, but they are insufficient for today’s needs because it has vagueness and focuses mostly on built infrastructures.
In this research, 14 Single Vegetation Object (SVO) Levels of Details (LOD) and four root LODs are proposed. They target to meet different adherence requirements and scales. Their formulation is based on LOD specification approaches, and on a needs analysis that identified the vegetation models and data most commonly required in applications in the urban environment. Vegetation LOD description approaches include semantic 3D modelling standards, industry, and common practices of municipality users which are also GIS data providers.
Current vegetation LOD descriptions approaches fall into two different groups based on the geometry they adopted for their specifications: implicit or explicit, and no one approach fulfills identified needs. Acquisition techniques and demand in IT resources have influenced the definitions of vegetation LODs, the adoption of one geometry type or the other, and the wide use (or not) of certain LODs.
Refined SVO LODs specifications of this research combine the strengths of each group with descriptions that cover beyond geometric specifications. Refined LODs incorporate implicit components, underground representations and reconstruction LODs not defined by any approach. With them, most datasets can be represented by at least one LOD, and modelers can tell what LOD is possible to implement based on the data they already have. For acquisition, it is possible to tell what data is required for a particular LOD, and which LOD can be used to obtain data needed for an application. The broad spectrum of refined LOD allows them to meet different requirements.
A shadow analysis case study was done with implementations of refined SVO LOD specifications. Acquisition from aerial and mobile LiDAR data was done in a workflow that brought the 0D tree inventory of the municipality of Rotterdam to 3D models using mainstream and open source tools. The case study confirmed a quantitative impact in shadow duration and extent by each LOD indicating that each is independently differentiated. Volumetric and non-volumetric models had different shadow over and underestimation impacts. The study further highlighted the properties of the crown of the real-world object that help in choosing a LOD and gave insights offered by lower LOD models.
The implementation of the assorted LODs revealed that while much research has been done in acquiring vegetation parameters from LiDAR data, the many options, methods and algorithms are scattered necessitating a unifying process or tool.
I present in this paper val3dity, an open-source software to validate 3D primitives according to the international definitions of ISO19107. Practitioners can use it directly, without limitations: its code is freely available under the GPLv3 license, both binaries and a web-application are publicly available. It takes as input several formats (including the international standard CityGML), and outputs a report that helps users identify and understand the errors.
I describe some of the engineering decisions supporting val3dity, and show that it can be used to validate real-world datasets.","Validation; Data quality; 3D city modelling; ISO19107; CityGML","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:5e9ed2f0-ec9e-4d9e-9a6b-57488ddd0222","http://resolver.tudelft.nl/uuid:5e9ed2f0-ec9e-4d9e-9a6b-57488ddd0222","Exploring the automatic Level of Detail inference for the validation of buildings in 3D city models","Dukai, Balázs (TU Delft Architecture and the Built Environment)","Biljecki, Filip (mentor); Ledoux, Hugo (graduation committee); Labetski, Anna (graduation committee); Lopes Gil, Jorge (graduation committee); Delft University of Technology (degree granting institution)","2018","There are several 3D city models available openly, worldwide. These models are used in various applications, from which many expects a homogeneous Level of Detail (LoD). Validating the accuracy of the LoD of a model requires the inference its LoD class and its conformance to the real-world object. This process quickly becomes infeasible for large models when done manually. Yet there is no automatic method for LoD inference and validation. Therefore the thesis proposes a method to automatically infer the geometric LoD (LoD0-2.3) in 3D city models.
A central aspect of this work is the use of machine-learning to classify building models based on their LoD. It follows the assumption that a process is possible where a classifier trained in a synthetic 3D city model containing all LoD classes, and applied in real city model. Therefore ten geometry measures (features) are computed from the objects and tested with six classification algorithms. The six experiments the transferability of a classifier from the synthetic city model to the real one, multi-class (LoD0-2.3) and binary (LoD2 or not) classification, and the effect of LoD class imbalance by introducing various amounts of LoD1 objects into the LoD2 model. Furthermore, by using a point cloud as ground truth, this explored the possibility of validating the inferred LoD classes.
The results indicate that the classifier is not transferable to the real data set when trained on the synthetic city model, which is probably due to the significant difference in object shapes between the two models. Binary classification outperforms the multi-class case and it is favourable for LoD validation where the main question is whether the model conforms the stated LoD or not. Finally, class-imbalance can reduce the classification with as much as 20%.","CityGML; Level of Detail; Machine Learning; 3D city model; Validation; Data Quality","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:fed24b16-cf95-4fa0-a109-ece6e91b61e9","http://resolver.tudelft.nl/uuid:fed24b16-cf95-4fa0-a109-ece6e91b61e9","A 3D data modeling approach for integrated management of below and above ground utility network features","den Duijn, Xander (TU Delft Architecture and the Built Environment)","Zlatanova, Sisi (mentor); Quak, Wilko (mentor); Wandl, Alexander (graduation committee); Delft University of Technology (degree granting institution)","2018","Precise and comprehensive knowledge about 3D urban space, critical infrastructures, and below ground features is required for simulation and analysis in the fields of urban and environmental planning, city administration and disaster management. In order to facilitate these applications, geo-information about functional, semantic, and topographic aspects of urban features, their mutual dependencies and relations are needed. Substantial work has been done in the modeling and representation of above ground features in the context of 3D city modelling by means of CityGML. However, the below ground part of the real world, of which utility networks form a big part, is often neglected in 3D city models. At the same time, several existing utility network data models exist. These are, however, commonly tailored to a specific domain and not suitable for the integrated modeling and representation of utility networks and city objects in 3D urban space
This research proposes a 3D data modeling approach for integrated management of below ground utility networks features (viz. electricity and sewer) and related above ground city objects (viz. streetlights and manhole covers). The data modeling approach is successfully examined by implementing relationships between 1) the below ground electricity network and above ground streetlights and 2) between the sewer network and the above ground manhole covers.
Having existing utility network data and city objects as input, a file in CityGML Utility Network ADE format is created. The manipulation of the data structure and content, according the proposed data modeling approach, is completed in FME. The output CityGML dataset allows interoperability but may become very large and objects may be arbitrarily nested leading to complex data structures. Therefore carefully optimized database schemas are required that enables efficient storage, management and data access of the CityGML data. The object-oriented CityGML data model, including the Utility Network ADE, is mapped to a relational database by means of the 3DCityDB. Subsequently, the CityGML data is inserted into the derived relational database. Several relevant (network) analyses are performed by querying the designed relational database. It shows the possibility to simulate what network features are affected by e.g. a utility strike by means of pgRouting and visualization in a GIS.
This research made one of the first attempts to thoroughly model existing utility network data and city objects according the CityGML Utility Network ADE. Following are further research that could optimize the proposed data modeling approach for better decision making in the field of asset management:
- Modeling multiple different utility networks and city objects
- Modeling in a higher LoD
- Detailing the CityGML Utility Network ADE classes and use
- Better investigating on more types of analyses
- Implementing larger datasets
- Implementing datasets with a different accuracy
- Exporting a CityGML file from the relational database
- Better investigating on visualization of the data
- Investigating on how to model different types of relationships","utility networks; electricity network; sewer network; data model; CityGML; Utility Network ADE; relationships; FME; PostgreSQL; PostGIS; relational database; 3DCityDB","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:937001de-3af5-4004-819a-fb2fbc428f4c","http://resolver.tudelft.nl/uuid:937001de-3af5-4004-819a-fb2fbc428f4c","3D Cadastres Best Practices, Chapter 3: 3D Cadastral Information Modelling","van Oosterom, P.J.M. (TU Delft OLD Department of GIS Technology); Lemmen, Chrit (Netherlands Cadastre); Thompson, R.J. (Queensland Government); Janecka, Karel (University of West Bohemia); Zlatanova, S. (TU Delft Urban Data Science); Kalantari, Mohsen (University of Melbourne)","","2018","In this chapter we address various aspects of 3D Cadastral Information Modelling. Of course, this is closely related to the legal framework and initial registration as presented in the first two chapters. Cadastral data models, such as the Land Administration Domain Model, which include 3D support, have been developed for legal information modelling and management purposes without providing correspondence to the object’s physical counterparts. Building Information Models and virtual 3D topographic/ city models (e.g. LandXML, InfraGML, CityGML, IndoorGML) can be used to describe the physical reality. The main focus of such models is on the physical and functional characteristics of urban structures (Aien et al, 2015). However, by definition, those two aspects need to be interrelated; i.e. a tunnel, a building, a mine, etc. always have both a legal status and boundaries as well as a physical description; while it is evident that their integration would maximise their utility and flexibility to support different applications. A model driven architecture approach, including the formalization of constraints is preferred. In the model driven architecture design approach as proposed by the Object Management Group the information model, often expressed in the form of a UML class diagram is the core of the development. This so-called Platform Independent Model (PIM, as presented in the current chapter) is then transformed into Platform Specific Model (PSM). This could be a relational database schema for a spatial DBMS (as will be discussed in the next chapter), or XML schema for a data exchange format or the structure of maps, forms and tables as used in the graphic user interface of a spatial application. Constraints have proved effective in providing the solutions needed to avoid errors and enable maintenance of data quality; thus the need to specify and implement them. This chapter explores possibilities of linking 3D legal right, restriction, responsibilities spaces, modelled with the Land Administration Domain Model (ISO 19152), with physical reality of 3D objects (described via CityGML, IFC, InfraGML, etc).","3D Information Modelling; 3D Cadastre; Standardization; LADM; CityGML; IndoorGML; LandXML; BIM/IFC","en","conference paper","International Federation of Surveyors (FIG)","","","","","","","","","","OLD Department of GIS Technology","","",""
"uuid:9c9fdacf-86ed-406e-81e6-3993b8056d64","http://resolver.tudelft.nl/uuid:9c9fdacf-86ed-406e-81e6-3993b8056d64","HSW: Heuristic Shrink-wrapping for automatically repairing solid-based CityGML LOD2 building models","Zhao, Junqiao (Tongji University); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science); Feng, Tiantian (Tongji University)","","2018","The Level-of-Detail (LOD) 2 building models defined in CityGML are used widely in three-dimensional (3D) city applications. Many of these applications demand valid solid-based geometry (closed 2-manifold), which is crucial for analytical and computational purposes. However, this condition is often violated in practice because of the way LOD2 models are constructed and exchanged. Examples of the resulting errors include missing surfaces, intersecting building parts, and superfluous interior geometry. In this study, we present a heuristic shrink-wrapping algorithm for reconstructing valid solid-based LOD2 buildings by repairing and generalizing invalid input models. A single building model is first decomposed as intersection-free and reassembled by constrained tetrahedralization. The bounding membrane is then shrunk by incrementally carving the selected boundary tetrahedra and wrapping the expected shape of the building. In the algorithm, combinations of heuristics are proposed to guide the carving process. Topological and geometrical constraints are proposed to ensure the validity and exactness of the output model. The semantics of the input geometry are preserved and missing semantics are deduced based on pragmatic rules. We evaluated the performance of the algorithm using 3D building models, including CityGML datasets. The results showed that our method achieved state-of-the-art performance at repairing 3D building models.","3D building model; CityGML; LOD; Model repair; Shrink-wrapping","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-04-21","","","Urban Data Science","","",""
"uuid:cc48a5e6-0121-41af-b52e-0d23b2597843","http://resolver.tudelft.nl/uuid:cc48a5e6-0121-41af-b52e-0d23b2597843","CityGML Application Domain Extension (ADE): overview of developments","Biljecki, F. (National University of Singapore); Kumar, Kavisha (TU Delft Urban Data Science); Nagel, Claus (virtualcitySYSTEMS GmbH)","","2018","The Application Domain Extension (ADE) is a built-in mechanism of CityGML to augment its data model with additional concepts required by particular use cases. The goal of this paper is to provide an overview of the ADE mechanism and a literature review of developments since its introduction a decade ago. The discovery of publications found that currently there are 44 ADEs supporting a wide range of applications, but also application-agnostic purposes such as harmonisation with national geographic information standards. We hope this paper to double as a reference material for the developers of new ADEs.","CityGML; ADE; 3D GIS; 3D city modelling","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:2f14a1b9-b179-4d3a-91ca-eecd2c5aea6a","http://resolver.tudelft.nl/uuid:2f14a1b9-b179-4d3a-91ca-eecd2c5aea6a","Topological Reconstruction of 3D City Models with preservation of semantics","Vitalis, S. (TU Delft Urban Data Science); Arroyo Ohori, G.A.K. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","Mansourian, Ali (editor); Pilesjö, Petter (editor); Harrie, Lars (editor); van Lammeren, Ron (editor)","2018","3D city models are becoming increasingly important for applications such as evacuation scenarios and energy consumption estimation. For these applications embedding semantic information on geometry is a key factor. The most popular implementation of modern 3D city models is based on the CityGML data model which describes spatial 3D data using a geometrical representation according to the GML encoding standard. While CityGML supports some basic storage of topological relationships between geometric objects, it fails to offer a true 3D topological representation of the city model. Alternatively, a true topological data structure can be used as an intermediate data model, to enable enforcing certain restrictions and operations that are more efficient for specific applications. In this article, we discuss a method that we have developed for the automatic conversion of CityGML models to a topological structure, while maintaining semantic information that was initially attached to the city objects. Such an approach raises certain challenges, as the geometries are not one-to-one analogous to the topological objects that are needed to represent them. We also provide a few examples that indicate that such a method is not trivial for retaining all information that was initially stored in a city model.","3D city models; CityGML; Combinatorial Maps; Linear Cell Complex; Topological Reconstruction","en","conference paper","Association of Geographic Information Laboratories for Europe (AGILE)","","","","","","","","","","Urban Data Science","","",""
"uuid:73b154d8-8006-48f0-b570-4ce80efe2717","http://resolver.tudelft.nl/uuid:73b154d8-8006-48f0-b570-4ce80efe2717","Modelling below- and above-ground utility network features with the CityGML Utility Network ADE: Experiences from Rotterdam","Den Duijn, X. (Student TU Delft); Agugiaro, G. (TU Delft Urban Data Science; AIT Austrian Institute of Technology); Zlatanova, S. (University of New South Wales)","","2018","Precise and comprehensive knowledge about 3D urban space is required for simulation and analysis in the fields of urban and environmental planning, city administration and disaster management. In order to facilitate these applications, geo-information about functional, semantic, and topographic aspects of urban features, their mutual dependencies and relations is needed. Substantial work has been done in the modelling and representation of above-ground features in the context of 3D city modelling. However, the belowground part of the real world, of which utility networks form a big part, is often neglected. Existing data models for utility networks are generally very domain-specific and, therefore, not suitable either. This paper describes a 3D data modelling approach for integrated management of below-ground utility networks and related above-ground city objects. This approach consists of manipulating first the structure of existing utility data in the commonly used Feature Manipulation Engine ETL software in order to make the data compliant to the CityGML Utility Network ADE data model. Subsequently, workspaces are created that take care of storing the CityGML data into the free and open-source 3D City Database, which has been extended in order to manage utility network data, too. Moreover, the research shows the suitability of the extended 3DCityDB to perform graph-based topological operations by means of the PostgreSQL pgRouting extension. Lastly, the results are visualized in typical GIS applications, e.g. QGIS and ArcGIS.","3D City Database; CityGML; PgRouting; Utility Network ADE; Utility networks","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:560bd9fb-7688-492f-b1c0-799644707be9","http://resolver.tudelft.nl/uuid:560bd9fb-7688-492f-b1c0-799644707be9","Bidirectional enrichment of CityGML and Multi-View Stereo Mesh models","Tryfona, Maya (TU Delft Architecture and the Built Environment; TU Delft Urban Data Science)","Ledoux, H. (mentor); Peters, R.Y. (graduation committee); Delft University of Technology (degree granting institution)","2017","The use of 3D city models has increased the last decades due to the evolution of technology. Their use is related to the need for solutions on issues that correspond to the building environment. Modelling aspects, like geometric, semantic information and topology are necessary, in order to provide an integrated result of spatial analysis. The creation of a complete 3D city model that contains all the needed information for an application, is a time consuming and complex process. Furthermore, different 3D city model formats can contain different aspects of the same features. For example, a CityGML model can have the semantic information of a 3D object, while a Multi-View Stereo Mesh model can contain all the geometric and appearance information of the same 3D object.
This thesis is documenting the possible enrichments that can be done bidirectionally between these two different 3D city model formats, when both exist for the same entities. Moreover, it presents the exploration of possible automated enrichment methodologies that can enrich each 3D city model automatically with information from the other one. Finally, an automatic bidirectional enrichment methodology is proposed and is implemented on a testing area, provided in the two different 3D city model formats. This method is based on distance computations between the meshes of the two 3D city models, used to match corresponding features, or part of features, in order to segment semantically the Multi-View Stereo Mesh model (roof, wall, road, terrain, uncertain) and transfer texture to the surfaces of the CityGML model that correspond with the surfaces of the Multi-View Stereo Mesh model.
In addition, distance computations are performed for the validation of the absence of buildings and the shapes of the roofs in the CityGML model, with respect to the information given from the Multi-View Stereo Mesh model. After the implementation of the proposed methodology, it is found that both 3D city model formats can be used for the proposed enrichments of either 3D city model format.
Future improvements are presented for the achievement of using existing information of different formats of 3D city models of the same entities, in order to supplement each 3D city model format with useful information, enhance the performance of spatial analysis and boost the evolution on the use of such models on real life applications.","CityGML; MVSM; bidirectional enrichment; 3D city model","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:b4095b0b-b267-410a-add7-fd87d5d6ca8f","http://resolver.tudelft.nl/uuid:b4095b0b-b267-410a-add7-fd87d5d6ca8f","Generating 3D city models without elevation data","Biljecki, F. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","","2017","Elevation datasets (e.g. point clouds) are an essential but often unavailable ingredient for the construction of 3D city models. We investigate in this paper to what extent can 3D city models be generated solely from 2D data without elevation measurements. We show that it is possible to predict the height of buildings from 2D data (their footprints and attributes available in volunteered geoinformation and cadastre), and then extrude their footprints to obtain 3D models suitable for a multitude of applications. The predictions have been carried out with machine learning techniques (random forests) using 10 different attributes and their combinations, which mirror different scenarios of completeness of real-world data. Some of the scenarios resulted in surprisingly good performance (given the circumstances): we have achieved a mean absolute error of 0.8m in the inferred heights, which satisfies the accuracy recommendations of CityGML for LOD1 models and the needs of several GIS analyses. We show that our method can be used in practice to generate 3D city models where there are no elevation data, and to supplement existing datasets with 3D models of newly constructed buildings to facilitate rapid update and maintenance of data.","3D city models; GIS; Building height; Lidar; Urban models; Urban morphology; Random forest; CityGML; LOD1; GIS; Building height; Lidar; Urban models; Urban morphology; Random forest; CityGML; LOD1","en","journal article","","","","","","","","2019-07-01","","","Urban Data Science","","",""
"uuid:6fe1dea8-53b3-4734-9e0c-ff01ed393d79","http://resolver.tudelft.nl/uuid:6fe1dea8-53b3-4734-9e0c-ff01ed393d79","Level of detail in 3D city models","Biljecki, F. (TU Delft Urban Data Science)","Stoter, J.E. (promotor); Ledoux, H. (copromotor); Delft University of Technology (degree granting institution)","2017","The concept of level of detail (LOD) describes the content of 3D city models and it plays an essential role during their life cycle. On one hand it comes akin to the concepts of scale in cartography and LOD in computer graphics, on the other hand it is a standalone concept that requires attention. LOD has an influence on tendering and acquisition, and it has a hand in storage, maintenance, and application aspects. However, it has not been significantly researched, and this PhD thesis fills this void.
This thesis reviews dozens of current LOD standards, revealing that most practitioners consider the LOD to be comprised solely of the geometric detail of data and there are disparate views on the concept as a whole. However, the research suggests that the LOD encompasses additional metrics, such as semantics and texture. The thesis formalises the concept, enabling integration and comparison of current LOD standards. The established framework may be applied to cartography and to different forms of 3D geoinformation such as point clouds.
Following the formalised concept, a new LOD specification is presented improving the LOD concept in the current OGC CityGML 2.0 standard, a prominent norm in the 3D GIS industry. The specification introduces 16 LODs for buildings that are shaped after analysing the capabilities of acquisition techniques and a large number of real-world datasets. The improved LOD specification may be integrated in product portfolios and tenders, preventing misunderstandings between stakeholders, and as a better language for communicating the specifics of a dataset to be acquired. The specification also considers different approaches to realise the data. Such geometric references result in dozens of different variants of the same LOD.
3D data according to the LOD specification was generated using a procedural modelling engine that was developed over the course of the research. The engine is capable of producing 3D city models in a large number of different variants and according to the CityGML standard.
The thesis also catalogues the many different ways to create 3D city models. A prominent technique for producing data in a different LOD is generalisation, i.e. simplifying a 3D city model. The inverse---augmenting the LOD of a dataset---has not been researched to a great extent, and this thesis gives an overview of the topic. This research demonstrates that it is possible to generate 3D city models without elevation measurements, inherently augmenting the LOD of coarser data (2D footprints). The method relies on machine learning: several attributes found in 2D datasets may hint at the height of a building, thus enabling extrusion and creating 3D city models suited for several applications.
Some acquisition techniques may result in multi-LOD datasets, and nowadays there are some regions represented in different, independent datasets. However, it was found that possibilities to link such data are deficient. The lack of linking mechanisms inhibits acquisition, storage, and maintenance of multi-LOD data. Two methods for linking features across two or more LODs have been developed resulting in an increased consistency of multi-LOD datasets. The first method links matching geometries across multiple LODs, while the second method establishes a 4D data structure in which the LOD is modelled as the fourth (spatial) dimension.
It is often believed that the more detailed 3D data the better. However, similarly as in computer graphics, dealing with data at fine LODs comes at a cost: such datasets are harder to obtain, their storage footprint is large, and their usage within a spatial analysis may be slow. Scarce research has been dedicated to investigating whether an increase in the LOD of the data brings a comparably significant increase in benefits when the data is used in a spatial analysis.
First, an analysis using real-world multi-LOD data was carried out. Different LODs of spatial data covering the Netherlands was used in a spatial analysis to refine population maps, obtaining different results for each LOD. However, several problems are exposed, revealing that using real data for such investigations is not optimal.
The remainder of the research focuses on using procedurally generated data for such experiments. Synthetic data in several different LODs has been generated and employed for four spatial analyses (estimation of the building shadow, envelope area, volume, and solar irradiation). The experiments result in different conclusions. Finer LODs usually bring some improvement to the quality of the spatial analysis, but not always and such may be negligible. The results of the experiments ultimately depend on the spatial analysis that is considered. The varying results between different spatial analyses make each of them unique. Furthermore, the benefit a finer LOD brings to a spatial analysis is not always clear and easily measurable. In short, striving to produce data at finer LODs may please the eye, but this is not always counter-balanced in the benefit it brings to a spatial analysis.
A further addition to the equation above is that when realised, 3D city models are unavoidably burdened with acquisition errors. An error propagation analysis was performed by disturbing the procedurally generated datasets with a range of simulated positional errors. Comparisons have been made between the intentionally degraded datasets and their error-free counterparts, thus obtaining the magnitude of uncertainty the positional errors cause in a spatial analysis. Based on these experiments, several findings are discovered, most importantly:
1. How the LODs are realised (which geometric references are used) has a larger influence than the LOD. A coarse LOD produced with a favourable geometric reference may yield better results than a finer LOD realised with an unfavourable reference.
2. Positional errors considerably affect spatial analyses. The effect is comparable across similar LODs. Simpler LODs are sligthly less affected by positional errors, but they may contain a large systematic error.
3. Errors induced in the acquisition process generally cancel out the improvement provided by finer LODs. The main conclusion is that in the considered spatial analyses the positional error has a significantly higher impact than the LOD. As a consequence, it is suggested that it is pointless to acquire geoinformation at a fine LOD if the acquisition method is not accurate, and instead it is advised to focus on the improvement of accuracy of the data.
The thesis proposes additional research for future work. For example, since this research focuses specifically on 3D building models, it would be worth extending the research to other urban features such as roads and vegetation. Furthermore, quality control in 3D GIS does not encompass the evaluation of the LOD of data. Hence integration of the LOD in quality standards should be a priority for future work.
necessitates application-specific and geometrically accurate and valid models. The concept of Levels of Detail (LoDs) indicate a model’s scale of adherence to its real-world counterpart. Highly detailed datasets often contain errors or require an exorbitant level of computing power. Given the high availability of LoD2 datasets, our research focuses on three considerations for generalising to LoD1: the vertical reference, extrusion vs. downtrusion and floor plan simplification. We present in this paper an initial methodology that produces geometrically accurate LoD1 models with a reduction of over 70% of the original file size.","Generalisation; 3D; City Model; CityGML; Levels of Detail","en","conference paper","University of Manchester","","","","","","","","","","Urban Data Science","","",""
"uuid:76878988-c401-4262-bc56-35282c95e298","http://resolver.tudelft.nl/uuid:76878988-c401-4262-bc56-35282c95e298","Free multi-floor indoor space extraction from complex 3D building models","Xiong, Qing (Wuhan University); Zhu, Qing (Southwest Jiaotong University; Wuhan University; Collaborative Innovation Center for Geospatial Technology); Du, Zhiqiang (Wuhan University; Collaborative Innovation Center for Geospatial Technology); Zlatanova, S. (TU Delft Urban Data Science); Zhang, Yeting (Wuhan University; Collaborative Innovation Center for Geospatial Technology); Zhou, Yan (University of Electric Science and Technology of China, Chengdu); Li, Yun (Southwest Jiaotong University)","","2016","Intelligent navigation and facility management in complex indoor environments are issues at the forefront of geospatial information science. Indoor spaces with fine geometric and semantic descriptions provide a solid foundation for various indoor applications, but it is difficult to comprehensively extract free multi-floor indoor spaces from complex three-dimensional building models, such as those described using CityGML LoD4, with existing methods for the subdivision or extraction of indoor spaces based on vector topology processing. Therefore, this paper elaborates a new voxelbased approach for extracting free multi-floor indoor spaces from 3D building models. It transforms the complicated vector processing tasks into a simple raster process that consists of three steps: voxelization with semantic enhancement, voxel classification, and boundary extraction. Experiments illustrate that the proposed method can automatically and correctly extract free multi-floor indoor spaces, especially two typical kinds of open indoor spaces, namely, lobbies and staircases.","Free multi-floor indoor space; CityGML LoD4; Indoor space extraction; Voxel","en","journal article","","","","","","Accepted Author Manuscript","","2017-11-25","","","Urban Data Science","","",""
"uuid:7837af15-87d5-4c6d-aed7-94fe6c24afa6","http://resolver.tudelft.nl/uuid:7837af15-87d5-4c6d-aed7-94fe6c24afa6","The most common geometric and semantic errors in CityGML datasets","Biljecki, F. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Du, X. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science); Soon, Kean Huat (Singapore Land Authority); Khoo, Victor (Singapore Land Authority)","Dimopoulou, E. (editor); van Oosterom, P. (editor)","2016","To be used as input in most simulation and modelling software, 3D city models should be geometrically and topologically valid, and semantically rich. We investigate in this paper what is the quality of currently available CityGML datasets, i.e. we validate the geometry/topology of the 3D primitives (Solid and MultiSurface), and we validate whether the semantics of the boundary surfaces of buildings is correct or not. We have analysed all the CityGML datasets we could find, both from portals of cities and on different websites, plus a few that were made available to us. We have thus validated 40M surfaces in 16M 3D primitives and 3.6M buildings found in 37 CityGML datasets originating from 9 countries, and produced by several companies with diverse software and acquisition techniques. The results indicate that CityGML datasets without errors are rare, and those that are nearly valid are mostly simple LOD1 models. We report on the most common errors we have found, and analyse them. One main observation is that many of these errors could be automatically fixed or prevented with simple modifications to the modelling software. Our principal aim is to highlight the most common errors so that these are not repeated in the future. We hope that our paper and the open-source software we have developed will help raise awareness for data quality among data providers and 3D GIS software producers.","CityGML; 3D city models; Quality control; Validation; Error","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"uuid:5255168d-4699-4e17-b638-52445e28748a","http://resolver.tudelft.nl/uuid:5255168d-4699-4e17-b638-52445e28748a","Proposal for a new LOD and multi-representation concept for CityGML","Löwner, Marc-O (Technische Universität Braunschweig); Gröger, Gerhard (CPA Software GmbH); Benner, Joachim (Karlsruhe Institut für Technologie); Biljecki, F. (TU Delft Urban Data Science); Nagel, Claus (virtualcitySYSTEMS GmbH)","Dimopoulou, E. (editor); van Oosterom, P. (editor)","2016","The Open Geospatial Consortium (OGC) CityGML standard offers a Level of Detail (LoD) concept that enables the representation of CityGML features from a very detailed to a less detailed description. Due to a rising application variety, the current LoD concept seems to be too inflexible. Here, we present a multi representation concept (MRC) that enables a user-defined definition of LoDs. Because CityGML is an international standard, official profiles of the MRC are proposed. However, encoding of the defined profiles reveals many problems including mapping the conceptual model to the normative encoding, missing technologies and so on. Therefore, we propose to use the MRC as a meta model for the further definition of an LoD concept for CityGML 3.0.","CityGML; Level of Detail; Multi-representation concept; Application Domain Extension; Profile","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"uuid:ebe92ed5-e4c4-4c05-9af7-4a121cfbd320","http://resolver.tudelft.nl/uuid:ebe92ed5-e4c4-4c05-9af7-4a121cfbd320","Extraction of the 3D Free Space from Building Model for Indoor Navigation","Diakite, A.A. (TU Delft Urban Data Science); Zlatanova, S. (TU Delft Urban Data Science)","","2016","For several decades, indoor navigation has been exclusively investigated in a 2D perspective, based on floor plans, projection and other 2D representations of buildings. Nevertheless, 3D representations are closer to our reality and offer a more intuitive description of the space configuration. Thanks to recent advances in 3D modelling, 3D navigation is timidly but increasingly gaining in interest through the indoor applications. But, because the structure of indoor environment is often more complex than outdoor, very simplified models are used and obstacles are not considered for indoor navigation leading to limited possibilities in complex buildings. In this paper we consider the entire configuration of the indoor environment in 3D and introduce a method to extract from it the actual navigable space as a network of connected 3D spaces (volumes). We describe how to construct such 3D free spaces from semantically rich and furnished IFC models. The approach combines the geometric, the topological and the semantic information available in a 3D model to isolate the free space from the rest of the components. Furthermore, the extraction of such navigable spaces in building models lacking of semantic information is also considered. A data structure named combinatorial maps is used to support the operations required by the process while preserving the topological and semantic information of the input models.","3D Indoor Navigation; Free Space Extraction; Navigable Space; IFC; CityGML; IndoorGML","en","journal article","","","","","","","","","","","Urban Data Science","","",""
"uuid:0a8a2c90-e8bb-40af-8981-cf8c50d8a6ce","http://resolver.tudelft.nl/uuid:0a8a2c90-e8bb-40af-8981-cf8c50d8a6ce","Resolution in photovoltaic potential computation","Alam, M.N. (Stuttgart University of Applied Sciences); Coors, V.; Zlatanova, S. (TU Delft Urban Data Science); van Oosterom, P.J.M. (TU Delft OLD Department of GIS Technology)","Zlatanova, S. (editor); Laurini, R. (editor); Baucic, M. (editor); Rumor, M. (editor); Ellul, C. (editor); Coors, V. (editor)","2016","In this paper, an analysis of the effect of the various types of resolution involved in photovoltaic potential computation is presented. To calculate solar energy incident on a surface, shadow from surrounding buildings has been considered. The incident energy on a surface has been calculated taking the orientation, tilt and position into consideration. Different sky visibility map has been created for direct and diffuse radiation and only the effect of resolution of the factors has been explored here. The following four resolutions are considered: 1. temporal resolution (1, 10, 60 minutes time interval for calculating visibility of sun), 2. object surface resolution (0.01, 0.1, 0.375, 0.75, 1.25, 2.5 and 5 m2 as maximum triangle size of a surface to be considered), 3. blocking obstacle resolution (number of triangles from LoD1, LoD2, or LoD3 CityGML building models), and 4. sky resolution (ranging from 150 to 600 sky-patches used to divide the sky-dome). Higher resolutions result in general in more precise estimation of the photovoltaic potential, but also the computation time is increasing, especially as realizes that this computation has to be done for every building with its object surface (both roofs and façades). This paper is the first in depth analysis ever of the effect of resolution and will help to configure the proper settings for effective photovoltaic potential computations.","Solar Potential; Shadow; Meshing Resolution; Time Interval; Sky View Factor; CityGML","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"uuid:97f85cf7-49fe-406e-b678-03f25830d493","http://resolver.tudelft.nl/uuid:97f85cf7-49fe-406e-b678-03f25830d493","Generation of multi-LOD 3D city models in CityGML with the procedural modelling engine Random3Dcity","Biljecki, F. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science)","Zlatanova, S. (editor); Laurini, R. (editor); Baucic, M. (editor); Rumor, M. (editor); Ellul, C. (editor); Coors, V. (editor)","2016","The production and dissemination of semantic 3D city models is rapidly increasing benefiting a growing number of use cases. However, their availability in multiple LODs and in the CityGML format is still problematic in practice. This hinders applications and experiments where multi-LOD datasets are required as input, for instance, to determine the performance of different LODs in a spatial analysis. An alternative approach to obtain 3D city models is to generate them with procedural modelling, which is – as we discuss in this paper – well suited as a method to source multi-LOD datasets useful for a number of applications. However, procedural modelling has not yet been employed for this purpose. Therefore, we have developed RANDOM3DCITY, an experimental procedural modelling engine for generating synthetic datasets of buildings and other urban features. The engine is designed to produce models in CityGML and does so in multiple LODs. Besides the generation of multiple geometric LODs, we implement the realisation of multiple levels of spatiosemantic coherence, geometric reference variants, and indoor representations. As a result of their permutations, each building can be generated in 392 different CityGML representations, an unprecedented number of modelling variants of the same feature. The datasets produced by RANDOM3DCITY are suited for several applications, as we show in this paper with documented uses. The developed engine is available under an open-source licence at Github at http://github.com/tudelft3d/Random3Dcity.","Procedural modelling; CityGML; Level of detail (LOD); Multi-Scale","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"uuid:50304527-b410-4f86-85ee-fbd004bc5928","http://resolver.tudelft.nl/uuid:50304527-b410-4f86-85ee-fbd004bc5928","The variants of an LOD of a 3D building model and their influence on spatial analyses","Biljecki, F. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Stoter, J.E. (TU Delft Urban Data Science); Vosselman, G. (University of Twente)","","2016","The level of detail (LOD) of a 3D city model indicates the model's grade and usability. However, there exist multiple valid variants of each LOD. As a consequence, the LOD concept is inconclusive as an instruction for the acquisition of 3D city models. For instance, the top surface of an LOD1 block model may be modelled at the eaves of a building or at its ridge height. Such variants, which we term geometric references, are often overlooked and are usually not documented in the metadata. Furthermore, the influence of a particular geometric reference on the performance of a spatial analysis is not known.In response to this research gap, we investigate a variety of LOD1 and LOD2 geometric references that are commonly employed, and perform numerical experiments to investigate their relative difference when used as input for different spatial analyses. We consider three use cases (estimation of the area of the building envelope, building volume, and shadows cast by buildings), and compute the deviations in a Monte Carlo simulation.The experiments, carried out with procedurally generated models, indicate that two 3D models representing the same building at the same LOD, but modelled according to different geometric references, may yield substantially different results when used in a spatial analysis. The outcome of our experiments also suggests that the geometric reference may have a bigger influence than the LOD, since an LOD1 with a specific geometric reference may yield a more accurate result than when using LOD2 models.","3D GIS; CityGML; Geometric reference; LOD1; LOD2","en","journal article","","","","","","","","2018-03-28","","","Urban Data Science","","",""
"uuid:6f644912-56c7-435f-b2c2-15456821fb90","http://resolver.tudelft.nl/uuid:6f644912-56c7-435f-b2c2-15456821fb90","Towards automatic semantic labelling of 3D city models","Rook, Merwin; Biljecki, F. (TU Delft Urban Data Science); Diakite, A.A. (TU Delft Urban Data Science)","Dimopoulou, E. (editor); van Oosterom, P. (editor)","2016","The lack of semantic information in many 3D city models is a considerable limiting factor in their use, as a lot of applications rely on semantics. Such information is not always available, since it is not collected at all times, it might be lost due to data transformation, or its lack may be caused by non-interoperability in data integration from other sources. This research is a first step in creating an automatic workflow that semantically labels plain 3D city model represented by a soup of polygons, with semantic and thematic information, as defined in the CityGML standard. The first step involves the reconstruction of the topology, which is used in a region growing algorithm that clusters upward facing adjacent triangles. Heuristic rules, embedded in a decision tree, are used to compute a likeliness score for these regions that either represent the ground (terrain) or a RoofSurface. Regions with a high likeliness score, to one of the two classes, are used to create a decision space, which is used in a support vector machine (SVM). Next, topological relations are utilised to select seeds that function as a start in a region growing algorithm, to create regions of triangles of other semantic classes. The topological relationships of the regions are used in the aggregation of the thematic building features. Finally, the level of detail is detected to generate the correct output in CityGML. The results show an accuracy between 85 % and 99 % in the automatic semantic labelling on four different test datasets. The paper is concluded by indicating problems and difficulties implying the next steps in the research.","3D city model; semantics; classification; CityGML; 3D GIS","en","conference paper","","","","","","","","","","","Urban Data Science","","",""
"uuid:c42166eb-bbc7-4cb5-ab94-309dbf82640f","http://resolver.tudelft.nl/uuid:c42166eb-bbc7-4cb5-ab94-309dbf82640f","Establishing a national 3D geo-data model for building data compliant to CityGML: Case of Turkey","Ates Aydar, S. (Istanbul Technical University); Stoter, J.E. (TU Delft Urban Data Science); Ledoux, H. (TU Delft Urban Data Science); Demir Ozbek, E. (Istanbul Technical University); Yomraliogly, T (Istanbul Technical University)","","2016","This paper presents the generation of the 3D national building geo-data model of Turkey, which is compatible with the international OGC CityGML Encoding Standard. We prepare an ADE named CityGML-TRKBIS.BI that is produced by extending existing thematic modules of CityGML according to TRKBIS needs. All thematic data groups in TRKBIS geo-data model have been remodelled in order to generate the national large scale 3D geo-data model for Turkey. Specific attention has been paid to data groups that have different class structure according to related CityGML data themes such as building data model. Current 2D geo-information model for building data theme of Turkey (TRKBIS.BI) was established based on INSPIRE specifications for building (Core 2D and Extended 2D profiles), ISO/TC 211 standards and OGC web services. New version of TRKBIS.BI which is established according to semantic and geometric rules of CityGML will represent 2D-2.5D and 3D objects. After a short overview on generic approach, this paper describes extending CityGML building data theme according to TRKBIS.BI through several steps. First, building models of both standards were compared according to their data structure, classes and attributes. Second, CityGML building model was extended with respect to TRKBIS needs and CityGML-TRKBIS Building ADE was established in UML. This study provides new insights into 3D applications in Turkey. The generated 3D geo-data model for building thematic class will be used as a common exchange format that meets 2D, 2.5D and 3D implementation needs at national level.