Algorithm and program for calculating evacuation time based on a PDF/image of an evacuation plan and converting it into an object and graph model

Abstract

Following the previous paper where an evacuation time calculation algorithm was implemented based on manually prepared data, this one formalizes a final end-to-end module for importing a PDF/image evacuation plan and automatically converting it into an object and graph model for further calculations according to DSTU standards. A hybrid Computer Vision pipeline is proposed: vector analysis of PDF objects (lines/polylines/texts/layers); raster branch using OpenCV (HSV segmentation of green «EXIT» signs and arrows, wall detection using LSD/Hough, door detection as local «gaps», morphological skeletonization, and distance transform for estimating the local passage width). The module output consists of a set of objects (exits, doors, stairs, sections, passages) and a directed graph (V, E) with attributes of length and width, directly consumed by the software from the first paper [1]. To evaluate the performance of automatic evacuation plan import, several key factors are considered. First, we check whether the system correctly finds the exits. Next, the accuracy of recognized directional arrows, which indicate movement orientation, is assessed. For corridors, it is important that the generated «passage mask» matches the actual layout. Additionally, the connectivity of the graph is analyzed — whether it is possible to reach an exit from any point — and whether the routes can be fully reconstructed. Moreover, the final outcome, the calculated evacuation time, is evaluated and compared with manual calculations according to the DSTU methodology. Thus, both the correctness of object recognition and the accuracy of the final calculations are verified. The result is the elimination of manual input to the program, reproducibility, and suitability for reporting. The module is integrated with the previously developed object-oriented software (classes Area, EvacuationRoute, Metrics; BFS/DFS), ensuring a full cycle.