Shape from Second-Bounce of Light Transport

Abstract

This paper describes a method to recover scene geometry from the second-bounce of light transport. We show that form factors (up to a scaling ambiguity) can be derived from the second-bounce component of light transport in a Lambertian case. The form factors carry information of the geometric relationship between every pair of scene points, i.e. , distance between scene points and relative surface orientations. Modelling the scene as polygonal, we develop a method to recover the scene geometry up to a scaling ambiguity from the form factors by optimization. Unlike other shape-from-intensity methods, our method simultaneously estimates depth and surface normal; therefore, our method can handle discontinuous surfaces as it can avoid surface normal integration. Various simulation and real-world experiments demonstrate the correctness of the proposed theory of shape recovery from light transport.