Design of Topologically Structured Geo-database for Interactive Navigation and Exploration in 3D Web-Based Urban Information Systems

Abstract

Three dimensional (3D) Geographic Information Systems (GIS) are the appropriate systems for storing, manipulating and visualizing spatial data in urban environments. Providing web-based interaction to these systems is quite challenging. In this paper we present the techniques and protocols incorporated into a web-based prototype for navigation and interaction in a virtual urban model automatically generated from a cadastral 2D GIS. The input data are 2D layers with lack of topology and feature/database linkage. The process generates a new set of three-dimensional urban entities topologically integrated in the geospatial database. The city surface is modeled considering the Digital Elevation Model (DEM) for realistic visualization in pedestrian navigation, especially important in hilly cities. Thus, road surface is partitioned into different geometric entities topologically integrated with the rest of urban elements in the database. The visualization process is performed using X3D as graphical language. The real street steepness and highly detailed facades can be easily distinguished, while the scene geometry is reduced enough to support interactive navigation and exploration.

Keywords: automatic 3D generation, DEM, spatial database, virtual urban environments, 3D web-based system