1. A system for determining the location of a target, comprising: a plurality of light sources; a projection surface with at least two sides, oriented in such a way that the light sources can illuminate one side of the projection surface; a target located entirely between the light sources and one side of the projection surface, and away from the projection surface; and an imaging device located on the side of the projection surface opposite the target, the imaging device being configured to detect a shadow from the target on the projection surface caused by individual ones of the light sources.