Photoelasticity (temporary strain birefringence) has long been utilized to transduce the stress in a material into an optical signal. It is demonstrated here that under certain conditions simple measurements (such as of area of birefringence) on optical signals resulting from stress applied to the surface of a photoelastic sheet are proportional to the magnitude of the vertical component of the applied force. These signals can be recorded photographically and consequently a photoelastic surface can be used to transduce dynamically the forces applied to that surface by natural phenomena. The polymeric material for the surface can be chosen to suit the range of stresses expected; gelatin is the most sensitive and adaptable material. Examples and applications are discussed.