A generalized exact arbitrary clearance technique for navigation meshes

Abstract

There are two frequent artifacts in crowd simulation, the first one appears when all agents attempt to traverse the navigation mesh sharing the same way point over portals, increasing the probability of collision against other agents and lining up towards portals; the second one is caused by way points being assigned at locations where clearance is not guaranteed which causes the agents to walk too close to the static geometry, slide along walls or even get stuck. In this work we propose a novel method for dynamically calculating way points based on current trajectory, destination, and clearance while using the full length of the portal, thus guaranteeing that agents in a crowd will have different way points assigned. To guarantee collision free paths we propose two novel techniques: the first one provides the computation of paths with clearance for cells of any shape (even with concavities) and the second one presents a new method for calculating portals with clearance, so that the dynamically assigned way points will always guarantee collision free paths. We evaluate our results with a variety of scenarios, and compare our results against traditional way points at the center of portals to show that our technique offers a better use of the space by the agents, as well as a reduction in the number of collisions.