Friso Penninga

Advances in 3D Geoinformation Systems

This unique book focuses on comparing several types of 3D models. Due to the rapid developments in sensor techniques a vast amount of 3D data is available. Effective algorithms for (semi) automatic object reconstruction are required. Integration of existing 2D objects with height data is a non-trivial process and needs further research. The resulting 3D models can be maintained in several types of 3D models: TEN (Tetrahedral Network), Constructive Solid Geometry (CSG) models, Regular Polytopes, TIN Boundary representation and 3D volume quad edge structure, layered/topology models, voxel based models, 3D models used in urban planning/polyhedrons, and n-dimensional models including time. 3D analysis and 3D simulation techniques explore and extend the possibilities in spatial applications.

A simplicial complex-based DBMS approach to 3D topographic data modelling

This paper introduces a new compact topological 3D data structure. The proposed method models the real world as a complete decomposition of space and this subdivision is represented by a constrained tetrahedral network (TEN). Operators and definitions from the mathematical field of simplicial homology are used to define and handle this TEN structure. Only tetrahedrons need to be stored explicitly in a (single column) database table, while all simplexes of lower dimensions, constraints and topological relationships can be derived in views. As a result the data structure is relatively compact and easy to update, while it still offers favourable characteristics from a computational point of view as well as presence of topological relationships.

3D topographic data modelling: why rigidity is preferable to pragmatism

In this paper two concepts for modelling 3D topography are introduced. The first concept is a very pragmatic approach of 3D modelling, trying to model as much as possible in (less complicated) 2.5D and use 3D modelling only in exceptional cases. The idea is to use a constrained TIN in 2.5D and place 3D TENs on top or below this surface. As both data structures use the same simplexes (nodes, edges, triangles) this integration should be very well possible. At a conceptual level this approach seems suitable, but at design level serious problems occur. To overcome these a rigid approach is developed, modelling all features in a 3D TEN, including the air above and earth beneath these topographic features. This model is stored and maintained within a spatial database. Despite its more advanced concept, it is shown that this approach offers huge advantages compared to the initial pragmatic approach.

Construction of the Planar Partition Postal Code Map Based on Cadastral Registration

Accurate postal code maps have many applications within GIS as the postal code has the potential to link the address description of buildings to their location in a specified global reference system in a more natural way. This relationship is possible in both directions: geocoding and reverse-geocoding. These operators demand a mechanism for translating an exact geometric position (i.e. WGS84 coordinate) into a location indication (town, street, house number) and vice versa. As most built-up parcels are provided with a postal code, this indicator can be used as the linkage. This paper describes the procedure, based on the Dutch cadastral registration, to obtain a reliable 6-position (i.e. 2628BX, the highest level of detail possible) planar postal code map for the Netherlands. Problems with existing, Voronoi-diagram based, postal code maps, like intersected houses and arbitrary derived (and thus unrecognizable) boundaries are avoided. The reliability of the derived planar postal code map is discussed and results are illustrated by figures. For a planar coverage, non built-up parcels having no postal code should be assigned a plausible postal code. Furthermore special attention is given to infrastructural parcels. These parcels are divided at their (approximated) skeletons first and then these subdivided infrastructure parcels are piecewise attached to their neighbour parcels. This new approach results in very reliable postal code maps, which are visually attractive too as infrastructure lines can be recognized. The procedure is generic and can be applied to other administrative parcel information as well. The algorithm is implemented using the Computational Geometry Algorithms Library (CGAL), and the possibilities and limitations of this library are addressed as well. Also a number of non-implemented alternatives or improvements are given.

A Compact Topological DBMS Data Structure For 3D Topography

The objective is to develop a data structure that is capable of handling large data volumes and offers support for querying, analysis and validation. Based on earlier results (i.e. the full decomposition of space, the use of a TEN structure and applying Poincare simplicial homology as mathematical foundation) a simplicial complex-based TEN structure is developed. Applying simplicial homology offers full control over orientation of simplexes and enables one to derive substantial parts of the TEN structure, instead of explicitly store the entire network. The described data structure is developed as a DBMS data structure and the usage of views, function based indexes and 3D R-trees result in a compact topological 3D data structure. Theoretical aspects of this approach are described earlier [12, 17,18]. This paper describes both theory and implementation of the approach.

A Tetrahedronized Irregular Network Based DBMS Approach for 3D Topographic Data Modeling

Topographic features such as physical objects become more complex due to increasing multiple land use. Increasing awareness of the importance of sustainable (urban) development leads to the need for 3D planning and analysis. As a result, topographic products need to be extended into the third dimension. In this paper, we developed a new topological 3D data model that relies on Poincare algebra. The internal structure is based on a network of simplexes, which are well defined, and very suitable for keeping the 3D data set consistent. More complex 3D features are based on this simple structure and computed when needed. We describe an implementation of this 3D model on a commercial DBMS. We also show how a 2D visualizer can be extended to visualize these 3D objects.

Implementation of a National 3D Standard : case of the Netherlands

This paper describes the motivation and problem statements as well as the ongoing investigations regarding the follow-up activities of the 3D Pilot NL. This pilot is a large collaboration in the Netherlands aiming at pushing 3D developments in the Netherlands. The first phase resulted in a national 3D standard, modeled as CityGML Application Domain Extension. Some insights obtained during this phase are sufficiently mature to be anchored in practice such as maintaining and further developing the 3D standard by Geon ovum and the provision of a countrywide 3D midscale base dataset which is currently under study at the Kadaster. Other results need further attention in a collaborative setting, specifically how the new 3D standard works in practice. This is currently being further explored in a second phase of the 3D Pilot in which over 100 organizations are participating. The goal of the follow-up pilot is more focused than the first pilot and aims at writing best practice documents by joint effort of the 3D Pilot community. The best practice documents are based on tools and techniques that are being developed for supporting the implementation of the 3D standard. Specific attention is being paid how to align City GML to the standard in the BIM (Building information Model) domain (IFC). Initial findings and work in progress are presented.

First implementation results and open issues on the Poincaré-TEN data structure

Modeling 3D geo-information has often been based on either simple extensions of 2D geo-information modeling principles without considering the additional 3D aspects related to correctness of representations or on 3D CAD based solutions applied to geo-information. Our approach is based from the scratch on modeling 3D geo-information based on the mathematically well-defined Poincare-TEN data structure. The feasibility of this approach still has to be verified in practice. In this paper, the first experiences of loading a reasonable sized data set, comprised of about 1,800 buildings represented by nearly 170,000 tetrahedrons (including the ‘air’ and ‘earth’), are discussed. Though the Poincare-TEN data structure is feasible, the experience gained during the implementation raises new research topics: physical storage in one (tetrahedron only) or two tables (tetrahedron and node), effective clustering and indexing improvements, more compact representations without losing too much performance, etc.

Generalization of integrated terrain elevation and 2D object models

A lot of attention has been paid to generalization (filtering) of Digital Elevation Models (DEMs) and the same is true for generalization of 2D object models (e.g. topographic or land use data). In addition there is a tendency to integrate DEMs with classified real-world objects or features, the result is sometimes called a Digital Terrain Model (DTM). However, there has not been much research on the generalization of these integrated elevation and object models. This paper describes a four step procedure. The first two steps have been implemented and tested with real world data (laser elevation point clouds and cadastral parcels). These tests have yielded promising results as will be shown in this paper.

Construction of the planar partition postal code map based on cadastral reGIStration

Accurate postal code maps could play an important role within GIS as the postal code has the potential to link the address description of buildings and their location in a certain global reference system. This relationship is possible in both directions: address matching and geocoding. These operators demand a certain mechanism in translating an exact geometric position (i.e. WGS84 coordinate) into a location indication (town, street, house number) and vice versa. As most built-up parcels are provided with a postal code this indicator could be used as the linkage. This paper describes the procedure, based on the Dutch cadastral reGIStration, to obtain a reliable 6-position planar postal code map for the Netherlands. Problems with existing postal code maps, like intersecting of houses and arbitrary derived boundaries are avoided.For a planar coverage, non built-up parcels having no assigned postal code should be assigned a plausible postal code. Therefore special attention is given to infrastructural parcels. These parcels are divided at their skeleton first and then piecewise attached to their neighbor parcels. This new approach results in very reliable postal code maps, which are visually attractive too as infrastructure lines can be regognized. The procedure is generic and can be applied to other administrative parcel information as well.The algorithm is implemented using the Computational Geometry Algorithms Library (CGAL), and the possibilities and limitations of this library are addressed as well. The reliability of the derived planar postal code map is discussed and some results are shown by figures. A short overview of alternatives and improvements concludes this paper.