A sketch-based interface for real-time control of crowd simulations that use navigation meshes

Controlling crowd simulations typically involves tweaking complex parameter sets to attempt to reach a desired outcome, which can be unintuitive for non-technical users. This paper presents an approach to control pedestrian simulations in real time via sketching. Most previous work has relied on grid-based navigation to support the sketching approach, however this does not scale well for large environments. In contrast, this paper makes use of a tiled navigation mesh (navmesh), based on the open source tool Recast, to support pedestrian navigation. The navmesh is updated in real time based on the user's sketches and the simulation updates accordingly. Users are able to create entrances/exits, barriers to block paths, flow lines to guide pedestrians, waypoint areas, and storyboards to specify the journeys of crowd subgroups. Additionally, a timeline interface can be used to control when simulation events occur. The effectiveness of the system is demonstrated with a set of scenarios which make use of a 3D model of an area of a UK city centre created using data from OpenStreetMap. This includes a comparison between the grid-based approach and our navmesh approach.