Determining hybrid reflectance properties and shape reconstruction by using indirect diffuse illumination method

In this paper, we propose the estimating method of reflectance properties and the recovery of shape by using Normal Sampler and Indirect Diffuse Illumination Method(IDIM). Photometric Stereo Method(PSM) is generally based on the direct illumination. PSM in this paper is modified with indirect diffuse illumination(IDI) and then applied to hybrid reflectance model which consists of two main components; Lambertian and specular reflectance. Under the indirect diffuse illumination, the reflectance properties of natural objects can be determined by using Normal Sampler that has almost all the normal components in the observed direction. The estimated reflectance properties are used to construct reference table. Also, 3-D shape of an object can be recovered from intensity distribution of a pixel and a reference table. In this paper, the reference table is used to recover the 3-D shape of an object and IDI simplifies the limited conditions of reflectance analysis for prior studies without any loss in performance. The proposed method can be applied to various types of surfaces which can be defined by hybrid reflectance.