Decomposing Global Light Transport using Time of Flight Imaging

Global light transport is composed of direct and indirect components. In this paper, we take the first steps toward analyzing light transport using high temporal resolution information via time of flight (ToF) images. The time profile at each pixel encodes complex interactions between the incident light and the scene geometry with spatially-varying material properties. We exploit the time profile to decompose light transport into its constituent direct, subsurface scattering, and inter reflection components. We show that the time profile is well modeled using a Gaussian function for the direct and inter reflection components, and a decaying exponential function for the subsurface scattering component. We use our direct, subsurface scattering, and inter reflection separation algorithm for four computer vision applications: recovering projective depth maps, identifying subsurface scattering objects, measuring parameters of analytical subsurface scattering models, and performing edge detection using ToF images.