Abstract: When taking building plans as the data source to construct indoor navigation models, the building plans lack topological information, especially the topological description of polygonal objects such as rooms and corridors.Therefore, an algorithm for automatically constructing the indoor spatial topological model is proposed.According to the characteristics of CAD building plans, the algorithm abstracts the wall line as an arc segment, the door and window as a point, and the room as a polygon. Then, starting from the starting wall line, the algorithm calculates the first wall line encountered clockwise or counterclockwise as the first edge of the target room or corridor, and so on, and finally returns to the starting wall line, completes the extraction of a room or corridor. Repeat the above process until all wall lines are marked twice, indicating that all rooms or corridors are extracted successfully. The topological relationship between doors and windows and rooms is based on the topological relationship between doors and windows and wall lines, and the topological relationship between doors and windows and rooms is deduced. Taking the building plan of a university teaching building as an example, the experiment show that the algorithm can effectively realize the automatic generation of indoor space topology model.

Key words: indoor navigation model, building plans, indoor topological model, indoor spatial data, topological relations