1. A system for counting riders arbitrarily positioned in a vehicle, the system comprising: a light source filtered for non-visible light and structured into a focused light beam; at least one camera filtered to capture non-visible light; a computer having a processor configured to: receive, from the at least one camera, video data corresponding to the vehicle passing through the light source; convert the video data into a 3D height map; and analyze the 3D height map to determine a number of riders in the vehicle.