Straight Skeleton Computation Optimized for Roof Model Generation

3D building models with roofs are important in several fields, such as urban planning and BIM (Building Information Model). However, enormous time and labor are required to create these 3D models. In order to automate laborious steps, a GIS and CG integrated system is proposed for the automatic generation of 3D building models, based on building polygons (building footprints) on digital maps. The generation is implemented through straight skeleton computation, in which three events (‘Edge’ and ‘Split’, ‘Vertex’ events) were proposed. In the computation process, usually three edges propagate into a node. Often it causes an acute angle shape that is not appropriate for roof boards. To avoid the inappropriate shape, in this paper, methodologies are proposed for adding ‘Line segment’ events besides the conventional events, and monotone polygon nodes sorting.