- document
-
Fu, Runnan (author), Pađen, I. (author), Garcia Sanchez, C. (author)Due to lack of information and long geometry generation times, tree geometries are usually oversimplified or even ignored in Computational Fluid Dynamic (CFD) simulations that predict wind and pollutant dispersion in urban areas. Nevertheless, trees are known to impact local wind patterns and air quality levels. Thus, in this paper we explore...journal article 2024
- document
-
Vitalis, S. (author), Arroyo Ohori, G.A.K. (author), Stoter, J.E. (author)Level of Detail (LoD) is a well known concept in 3D city models, used to designate different geometric detail that can be used in different applications. Nevertheless, multi-LoD datasets are hard to maintain and manage because of their intrinsic complexity. Versioning is a solution that aids in the storage and management of big and complex...journal article 2022
- document
-
van Oosterom, P.J.M. (author), van Oosterom, S.J.M. (author), Liu, Haicheng (author), Thompson, R.J. (author), Meijers, B.M. (author), Verbree, E. (author)Point clouds contain high detail and high accuracy geometry representation of the scanned Earth surface parts. To manage the huge amount of data, the point clouds are traditionally organized on location and map-scale; e.g. in an octree structure, where top-levels of the tree contain few points suitable for small scale overviews and lower...journal article 2022
- document
-
Garcia Sanchez, C. (author), Vitalis, S. (author), Pađen, I. (author), Stoter, J.E. (author)Climate change and urbanization rates are transforming urban environments, making the use of 3D city models in computational fluid dynamics (CFD) a fundamental ingredient to evaluate urban layouts before construction. However, current geometries used in CFD simulations tend to be built by CFD experts to test specific cases, most of the times...journal article 2021
- document
-
Roth, Thorsten (author), Weier, Martin (author), Bauszat, P. (author), Hinkenjann, André (author), Li, Yongmin (author)Modern Monte-Carlo-based rendering systems still suffer from the computational complexity involved in the generation of noise-free images, making it challenging to synthesize interactive previews. We present a framework suited for rendering such previews of static scenes using a caching technique that builds upon a linkless octree. Our...journal article 2020
- document
-
Zhang, L. (author), van Oosterom, P.J.M. (author), Liu, H. (author)Point clouds have become one of the most popular sources of data in geospatial fields due to their availability and flexibility. However, because of the large amount of data and the limited resources of mobile devices, the use of point clouds in mobile Augmented Reality applications is still quite limited. Many current mobile AR applications...journal article 2020
- document
-
Kumar, Kavisha (author), Labetski, A. (author), Ledoux, H. (author), Stoter, J.E. (author)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,...journal article 2019
- document
-
Yang, M. (author), Lopez Dekker, F.J. (author), Dheenathayalan, P. (author), Biljecki, Filip (author), Liao, Mingsheng (author), Hanssen, R.F. (author)Persistent scatterers (PSs) are coherent measurement points obtained from time series of satellite radar images, which are used to detect and estimate millimeter-scale displacements of the terrain or man-made structures. However, associating these measurement points with specific physical objects is not straightforward, which hampers the...journal article 2019
- document
-
Labetski, A. (author), van Gerwen, Stefan (author), Tamminga, G.F. (author), Ledoux, H. (author), Stoter, J.E. (author)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...conference paper 2018
- document
-
Guan, X. (author), van Oosterom, P.J.M. (author), Cheng, Bo (author)Because of their locality preservation properties, Space-Filling Curves (SFC) have been widely used in massive point dataset management. However, the completeness, universality, and scalability of current SFC implementations are still not well resolved. To address this problem, a generic n-dimensional (nD) SFC library is proposed and...journal article 2018
- document
-
Liu, H. (author), van Oosterom, P.J.M. (author), Meijers, B.M. (author), Verbree, E. (author)Indoor navigation and visualization become increasingly important nowadays. Meanwhile, the proliferation of new sensors as well as the advancement of data processing provide massive point clouds to model the indoor environment in high accuracy. However, current state-of-the-art solutions fail to manage such large datasets efficiently. File...journal article 2018
- document
-
Labetski, A. (author), Ledoux, H. (author), Stoter, J.E. (author)The increasing popularity of 3D city models in navigation, urban planning, etc.,<br/>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...conference paper 2017
- document
-
Löwner, Marc-O (author), Gröger, Gerhard (author), Benner, Joachim (author), Biljecki, F. (author), Nagel, Claus (author)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...conference paper 2016
- document
-
Biljecki, F. (author), Ledoux, H. (author), Stoter, J.E. (author)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...conference paper 2016
- document
-
Arroyo Ohori, G.A.K. (author), Ledoux, H. (author), Stoter, J.E. (author)3D city models of the same region at multiple LODs are encumbered by the lack of links between corresponding objects across LODs. In practice, this causes inconsistency during updates and maintenance problems. A radical solution to this problem is to model the LOD of a model as a dimension in the geometric sense, such that a set of connected...conference paper 2015
- document
-
Arroyo Ohori, G.A.K. (author), Ledoux, H. (author), Biljecki, F. (author), Stoter, J.E. (author)The various levels of detail (LODs) of a 3D city model are often stored independently, without links between the representations of the same object, causing inconsistencies, as well as update and maintenance problems. One solution to this problem is to model the LOD as an extra geometric dimension perpendicular to the three spatial ones,...journal article 2015
- document
-
Biljecki, F. (author), Ledoux, H. (author), Stoter, J.E. (author)The geometry of the LOD1 block model of CityGML may be represented in a multitude of valid variants, e.g. it may represent individual buildings or aggregated blocks. The geometric representations within each of these, such as the reference of the footprint of a building, are not standardised in CityGML and are not informed in the metadata. The...conference paper 2014
- document
-
Biljecki, F. (author), Ledoux, H. (author), Stoter, J.E. (author), Zhao, J. (author)The level of detail in 3D city modelling, despite its usefulness and importance, is still an ambiguous and undefined term. It is used for the communication of how thoroughly real-world features have been acquired and modelled, as we demonstrate in this paper. Its definitions vary greatly between practitioners, standards and institutions. We...journal article 2014
- document
-
Schmal, J.P. (author)Dynamic chemical process modelling is still largely considered an art. In this thesis the theory of large-scale chemical process modelling and validation is discussed and initial steps to extend the theory are explored. In particular we pay attention to the effect of the level of detail on the model simulation and optimisation performance. We...doctoral thesis 2014
- document
-
Biljecki, F. (author), Zhao, J. (author), Stoter, J.E. (author), Ledoux, H. (author)This review paper discusses the concept of level of detail in 3D city modelling, and is a first step towards a foundation for a standardised definition. As an introduction, a few level of detail specifications, outlooks and approaches are given from the industry. The paper analyses the general uncertainties and shortcomings around the concept of...conference paper 2013