Surface Normal Estimation From Optimized and Distributed Light Sources Using DNN-Based Photometric Stereo

Photometric stereo (PS) is a major technique to recover surface normal for each pixel. However, since it assumes Lambertian surface and directional light to estimate the value, a large number of images are usually required to avoid the effects of outliers and noise. In this paper, we propose a technique to reduce the number of images by using distributed light sources, where the patterns are optimized by a deep neural network (DNN). In addition, to efficiently realize the distributed light, we use an optical diffuser with a video projector, where the diffuser is illuminated by the projector from behind, the illuminated area on the diffuser works as if an arbitrary-shaped area light. To estimate the surface normal using the distributed light source, we propose a near-light photometric stereo (NLPS) using DNN. Since optimization of the pattern of distributed light is achieved by a differentiable renderer, it is connected with NLPS network, achieving end-to-end learning. The experiments are conducted to show the successful estimation of the surface normal by our method from a small number of images.