Abstract
The growing demand for virtual urban models in emerging areas of interest has promoted a variety of techniques for automating the creation of virtual scenes with a high level of realism. However, visualization is not always the only aim in many applications. Increasingly, urban systems are also required for management, analysis, or interaction with very different types of information. Three-dimensional (3D) urban entities should maintain neighbor relations, and being inserted in a geospatial database in order to enable associative queries, one of the most important features associated with 3D urban geographic information system (GIS). Additional challenges are found when these three-dimensional models are implemented in web-based systems. This paper proposes a method for automatic modeling of buildings and street surfaces of entire real cities by combining computer graphics, computational geometry, and GIS techniques. The sources of information employed are two-dimensional (2D) GIS and its associated digital elevation models (DEMs) in order to provide real terrain features. The virtual environment supports web-based navigation and data interaction. The case study was performed in Jaen, Spain, a hilly city with more than 1,000 blocks of buildings. The 3D city model was generated using the public data provided by the general cadastral office of Jaen and the DEM information of this area. The topological relations between the geometric urban entities were inserted in the spatial database and the graphics and thematic information could be accessed through the Internet. All these features are highly desirable for decision making in urban planning. DOI: 10.1061/(ASCE)UP.1943-5444.0000131. (C) 2013 American Society of Civil Engineers.

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