Fig. 1

Illustration of a the space–time prism in a three-dimensional space–time cube and its projection on the 2D geographic space, known as the potential path area (PPA); b PPA intersections (light yellow ellipses) to identify potential interaction between two moving entities (modified from [31, 37]). Two trajectories are outlined in red and blue. Two sets of continuous intersection segments are outlined using black rectangles, capturing a concurrent interaction on the left, and an encounter segment on the right