Subpixel Photometric Stereo

Conventional photometric stereo recovers one normal direction per pixel of the input image. This fundamentally limits the scale of recovered geometry to the resolution of the input image, and does not adequately model surfaces with subpixel geometric structures. In this paper, we propose a method to recover subpixel surface geometry by studying the relationship between the subpixel geometry and the reflectance properties of a surface. We first describe a generalized physically-based reflectance model that relates the distribution of surface normals inside each pixel area to its reflectance function. The distribution of surface normals can be computed from the reflectance functions recorded in photometric stereo images. A convexity measure of subpixel geometry structure is also recovered at each pixel, through an analysis of brightness attenuation due to shadowing. Then, we use the recovered distribution of surface normals and the surface convexity to infer subpixel geometric structures...

• Type: Journal
• Year: 2008
• Where: PAMI
• Authors: Ping Tan, Stephen Lin, Long Quan
• Keywords: Input Image, PAMI 2008, Subpixel, Surface Normals