Refractive index and transmission coefficient recovery algorithm of crystal-like objects

Current inverse global illumination techniques focus on the investigation of opaque objects. In this paper, we present a new method for recovering material properties of crystal-like objects. First of all, the objects in the image are separated into two classes: the opaque objects and the translucent objects. For the translucent objects, by analyzing refractive phenomena, we propose a method to recover an approximation of the refractive index and transmission coefficients. First, obtain the refractive index with the minimum error of color variance by a certain step calculations and then iteratively recover the color parameters. Experiments show that our algorithms can be completed in few iterative steps, and recovery error is very small. With the recovered material properties, the scene can be rendered under novel lighting or viewing conditions, and it can also be rendered when new objects are added into the scene.