1. A system, comprising: a pressure sensitive material that provides an indication of applied pressure for a plurality of locations on the material; and a non-transitory computer-readable storage medium for a processing device in communication with the pressure sensitive material, including instructions to: receive the indication of applied pressure; determine, for each of a plurality of measurement periods, a pressure image from the indication of applied pressure such that a sequence of pressure images is determined; and construct a manifold representing the sequence of pressure images.