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Peters, R.Y. (author), Ledoux, H. (author)Governments and companies around the world collect point clouds (datasets containing elevation points) because these are useful for many applications, e.g. to reconstruct 3D city models, to understand and predict the impact of floods, and to monitor dikes. We address in this paper the visualisation of point clouds, which is perhaps the most...journal article 2016
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Arroyo Ohori, G.A.K. (author), Ledoux, H. (author), Stoter, J.E. (author)An alternative to the traditional approaches to model separately 2D/3D space, time, scale and other parametrisable characteristics in GIS lies in the higher-dimensional modelling of geographic information, in which a chosen set of non-spatial characteristics, e.g. time and scale, are modelled as extra geometric dimensions perpendicular to the...conference paper 2016
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Ates Aydar, S. (author), Stoter, J.E. (author), Ledoux, H. (author), Demir Ozbek, E. (author), Yomraliogly, T (author)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...conference paper 2016
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Kumar, Kavisha (author), Ledoux, H. (author), Stoter, J.E. (author)In addition to buildings, the terrain forms an important part of a 3D city model. Although in GIS terrains are usually represented with 2D grids, TINs are also increasingly being used in practice. One example is 3DTOP10NL, the 3D city model covering the whole of the Netherlands, which stores the relief with a constrained TIN containing more than...conference paper 2016
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Kumar, Kavisha (author), Ledoux, H. (author), Stoter, J.E. (author)Point cloud data are an important source for 3D geoinformation. Modern day 3D data acquisition and processing techniques such as airborne laser scanning and multi-beam echosounding generate billions of 3D points for simply an area of few square kilometers. With the size of the point clouds exceeding the billion mark for even a small area,...conference paper 2016
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Stoter, J.E. (author), Ledoux, H. (author), Zlatanova, S. (author), Biljecki, F. (author)This paper summarises the on going research activities of the 3D Geoinformation Group at the Delft University of Technology. The main challenge underpinning the research of this group is providing clean and appropriate 3D data about our environment in order to serve a wide variety of applications. The research aims at designing, developing and...conference paper 2016
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Donkers, S (author), Ledoux, H. (author), Zhao, J. (author), Stoter, J.E. (author)Although the international standard CityGML has five levels of detail (LODs), the vast majority of available models are the coarse ones (up to LOD2, i.e. block-shaped buildings with roofs). LOD3 and LOD4 models, which contain architectural details such as balconies, windows and rooms, rarely exist because, unlike coarser LODs, their construction...journal article 2016
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Stoter, J.E. (author), Vallet, B. (author), Lithen, T. (author), Pla, M (author), Wozniak, P. (author), Kellenberger, T (author), Streilein, A (author), Ilves, R. (author), Ledoux, H. (author)Techniques for 3D mapping are maturing. At the same time the need for 3D data is increasing. This has pushed national (and regional) mapping agencies (NMAs) to consider extending their traditional task of providing topographic data into the third dimension. To show how research results in 3D mapping obtained over the past twenty years have...conference paper 2016
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Biljecki, F. (author), Ledoux, H. (author), Stoter, J.E. (author)The level of detail (LOD) concept of the OGC standard CityGML 2.0 is intended to differentiate multi-scale representations of semantic 3D city models. The concept is in practice principally used to indicate the geometric detail of a model, primarily of buildings. Despite the popularity and the general acceptance of this categorisation, we argue...journal article 2016
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Biljecki, F. (author), Stoter, J.E. (author), Ledoux, H. (author), Zlatanova, S. (author), Coltekin, A. (author)In the last decades, 3D city models appear to have been predominantly used for visualisation; however, today they are being increasingly employed in a number of domains and for a large range of tasks beyond visualisation. In this paper, we seek to understand and document the state of the art regarding the utilisation of 3D city models across...journal article 2015
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Peters, R. (author), Ledoux, H. (author), Biljecki, F. (author)Visibility analysis is an important application of 3D GIS data. Current approaches require 3D city models that are often derived from detailed aerial point clouds. We present an approach to visibility analysis that does not require a city model but works directly on the point cloud. Our approach is based on the medial axis transform, which...conference paper 2015
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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
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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
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Biljecki, F. (author), Ledoux, H. (author), Stoter, J.E. (author)Cities are increasingly adopting 3D city models for 3D visualisation, computing solar panel potential of roofs, and other applications. In a similar way to traditional maps, 3D models are an abstraction of the real world: certain elements are simplifi ed or omitted. The amount of detail that is captured in a 3D model, both in terms of geometry...journal article 2014
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Peters, R.Y. (author), Ledoux, H. (author), Meijers, B.M. (author)We introduce a new approach for the generation and the generalisation of visually smooth depth-contours for hydrographic charts. Unlike most current approaches, it strictly respects the safety constraint that dictates that the resulting chart may not indicate a depth shallower than originally measured. The main idea is to construct a smooth...journal article 2014
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Biljecki, F. (author), Ledoux, H. (author), Stoter, J.E. (author)The CityGML standard enables the modelling of some topological relationships, and the representation in multiple levels of detail (LODs). However, both concepts are rarely utilised in reality. In this paper we investigate the linking of corresponding geometric features across multiple representations. We describe the possible topological cases,...conference paper 2014
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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
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Biljecki, F. (author), Ledoux, H. (author), Stoter, J. (author)This paper describes the analysis of the propagation of positional uncertainty in 3D city models to the uncertainty in the computation of their volumes. Current work related to error propagation in GIS is limited to 2D data and 2D GIS operations, especially of rasters. In this research we have (1) developed two engines, one that generates random...conference paper 2014
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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
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Zhao, Z. (author), Ledoux, H. (author), Stoter, J.E. (author)The LoD2 building models defined in CityGML are widely used in 3D city applications. The underlying geometry for such models is a GML solid (without interior shells), whose boundary should be a closed 2-manifold. However, this condition is often violated in practice because of the way LoD2 models are constructed and exchanged. Examples of the...conference paper 2013