Automatic Generation of 3-D Building Models by Generalized Building Polygon Partitioning

Abstract

Building polygons are buildings' contours on the digital map stored by GIS. Based on building polygons, GIS and CG integrated system automatically generates multiple-roofed 3-D building models. A 3-D urban model including 3-D building models is the important information infrastructure that can be utilized in several fields, such as landscape evaluation, urban planning, disaster prevention simulation, etc. However, to realize a 3-D urban model enormous time and labor have to be consumed to design hundreds and thousands of 3-D building models. In order to automate the labor, the system aims at creating 3-D building models automatically from building polygons. If a building polygon has right angle only, then it can be divided in rectangles. We propose the useful polygon expression where the building polygon can be expressed as a set of its edges' turning direction (RL expression) and that decides from which vertex a dividing line (DL) is drawn. In order to generate 'probable' multiple-roofed building models, we propose the scheme of prioritizing the DL that forms a branch roof, based on the length of the DL. This scheme generates probable 3-D building models whose main roofs are higher than branch roofs.