Knowledge-based automatic generation of 3D building models from building footprint by straight skeleton computation

3D urban models are important in several fields, such as urban planning and gaming industries. However, enormous time and labour has to be consumed to create these 3D models. In order to automate laborious steps, a GIS and CG integrated system was proposed for automatically generating 3D building models, based on building polygons (building footprints) on digital maps. For either orthogonal or non-orthogonal building polygons, the knowledge-based system is proposed for automatically generating 3D building models with general shaped roofs by straight skeleton computation. In this paper, the algorithm for 'split event' is clarified and the new methodology is presented for constructing roof models by assuming the third event: 'simultaneous event' and, at the end of the shrinking process, some polygons are converged to 'a line of convergence'.