An algorithm for on-the-fly K shortest paths finding in multi-storey buildings using a hierarchical topology model

This article presents an approach to computing K shortest paths in large buildings with complex horizontal and vertical connectivity. The building topology is obtained from Building Information Model (BIM) and implemented using directed multigraphs. Hierarchical design allows the calculation of feasible paths without the need to load into memory the topology of the entire building. It is possible to expand the graph with new connectivity on-the-fly. The paths calculated may be composed of traversable building components that are located inside the buildings or those that are both inside and outside buildings. The performance (computational time and heap size used) is optimized by using the appropriate collections (maps, lists and sets). The proposed algorithm is evaluated in several use-case scenarios – complete graphs and real building environments. In all test scenarios, the proposed path finding algorithm is faster and uses less memory when compared to the fast version of the Yen’s KSP algorithm. The proposed approach can be successfully used as a first level of coarse-to-fine path finding algorithms.