Polarization-sensitive thermal imaging

In order to recognize 3-D objects, conventional methods in robot vision perform shape extraction by sensing the intensity of light reflected by objects. A fundamental problem associated with sensing the intensity of reflected light is that intensity gives one parameter while the surface orientation of objects has two degrees of freedom. Physics Innovations Inc. is developing a thermal imaging technique for determining surface orientation where, in each image pixel, two parameters are sensed simultaneously. The two parameters, percent of polarization P and angle of the plane of polarization (phi) , are directly related to the two angles of surface orientation. In this paper the uncertainties in determining P, and (phi) using the Physics Innovations sensor are made explicit by analytical expressions and by computer simulations of the images. These uncertainties are related to temporal and spatial noise characteristics of the imaging system and to the polarization efficiencies of the polarizers. Automatic object recognition using polarization information is dependent on the uncertainties in determining P, and (phi) .