Uncalibrated photometric stereo constrained by intrinsic reflectance image and shape from silhoutte

Shuhei Hashimoto, Daisuke Miyazaki, Shinsaku Hiura

Abstract: Photometric stereo is a method which estimates surface normal from object's shading. Uncalibrated photometric stereo is the photometric stereo where the light source direction is unknown. Uncalibrated photometric stereo which estimates both light source direction and surface normal is an ill-posed problem, and has ambiguity for solving the problem. In order to uniquely determine the solution, constraints should be added. Two constraints we use are the intrinsic image which represents the albedo (diffuse reflectance) and the guide normal which represents the approximate shape of the object. Estimation of albedo requires both the normal and the light direction to be known, but both are unknown in our situation. Our method employs the idea of intrinsic image decomposition, and estimates the reflectance solely from input image sequence. In addition, we estimate the approximate shape from images without using other sensors such as laser range sensor. This paper reveals that the uncalibrated photometric stereo can be solved by these two constraints.