Abstract:
New developments in urban planning, especially in environmentally oriented analysis including noise, air pollution, urban climate etc., call for new demands on authorities and planners. Due to the increasing availability of informations systems and of 3D-data, planners and municipalities emphasize modeling the urban space in three dimensions. While the visualization aspect is often and detailed considered, only a few investigations about interactive aspects on urban planning are available. In this paper we present a framework for a 3D-urban-GIS. This includesvconceptual aspects and a ®rst outline and implementation of an application prototype. For this representation, new scopes have to be considered from data acquisition to modeling and to storage. First, the urban object space is classifed in an hierarchical 3D object structure. In accordance to different planning levels (i.e., levels-of-detail), several data acquisition methods are fused to obtain 3D datasets. The results show that a context speci®c methodology has to be de®ned. This includes planning aspects that are traditionally not available in GIS. Based on test sites in Rostock and Stuttgart, a 3D urban-GIS prototype is in development, joining aspects of a 3D-visualization interface and a database for 3D objects.
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Lee J, Kwan M. A combinatorial data model for representing topological relations among 3D geographical features in micro‐spatial environments. International Journal of Geographical Information Science [serial online]. November 2005;19(10):1039-1056. Available from: Academic Search Premier, Ipswich, MA. Accessed March 28, 2009.
Abstract:
This research is motivated by the need for 3D GIS data models that allow for 3D spatial query, analysis and visualization of the subunits and internal network structure of ‘micro‐spatial environments’ (the 3D spatial structure within buildings). It explores a new way of representing the topological relationships among 3D geographical features such as buildings and their internal partitions or subunits. The 3D topological data model is called the combinatorial data model (CDM). It is a logical data model that simplifies and abstracts the complex topological relationships among 3D features through a hierarchical network structure called the node‐relation structure (NRS). This logical network structure is abstracted by using the property of Poincaré duality. It is modelled and presented in the paper using graph‐theoretic formalisms. The model was implemented with real data for evaluating its effectiveness for performing 3D spatial queries and visualization.
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Ellul C, Haklay M. Requirements for Topology in 3D GIS. Transactions in GIS [serial online]. March 2006;10(2):157-175. Available from: Academic Search Premier, Ipswich, MA. Accessed March 28, 2009.
Abstract:
Topology and its various benefits are well understood within the context of 2D Geographical Information Systems. However, requirements in three-dimensional (3D) applications have yet to be defined, with factors such as lack of users’ familiarity with the potential of such systems impeding this process. In this paper, we identify and review a number of requirements for topology in 3D applications. The review utilises existing topological frameworks and data models as a starting point. Three key areas were studied for the purposes of requirements identification, namely existing 2D topological systems, requirements for visualisation in 3D and requirements for 3D analysis supported by topology. This was followed by analysis of application areas such as earth sciences and urban modelling which are traditionally associated with GIS, as well as others including medical, biological and chemical science. Requirements for topological functionality in 3D were then grouped and categorised. The paper concludes by suggesting that these requirements can be used as a basis for the implementation of topology in 3D. It is the aim of this review to serve as a focus for further discussion and identification of additional applications that would benefit from 3D topology.
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Lee J. A Spatial Access-Oriented Implementation of a 3-D GIS Topological Data Model for Urban Entities. GeoInformatica [serial online]. September 2004;8(3):237-264. Available from: Academic Search Premier, Ipswich, MA. Accessed March 28, 2009.
Abstract:
3-D analysis in GIS is still one of the most challenging topics for research. With the goal being to model possible movement within the built environment, this paper, therefore, proposes a new approach to handling connectivity relationships among 3-D objects in urban environments in order to implement spatial access analyses in 3-D space. To achieve this goal, this paper introduces a 3-D network data model called the geometric network model (GNM), which has been developed by transforming the combinatorial data model (CDM), representing a connectivity relationship among 3-D objects using a dual graph. For the transformation, this paper presents (1) an O(n2) algorithm for computing a straight medial axis transformation (MAT), (2) the processes for transforming phenomena from 3-D CDM to 3-D GNM, and (3) spatial access algorithms for the 3-D geometric network based upon the Dijkstra algorithm. Using the reconstructed geometric network generated from the transformations, spatial queries based upon the complex connectivity relationships between 3-D urban entities are implemented using Dijkstra algorithm. Finally, the paper presents the results of an experimental implementation of a 3-D network data model (GNM) using GIS data of an area in downtown Columbus, Ohio.
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