Rendering method of translucent material in Blinn-Phong model using transparency coefficient with refractive index

Abstract

In general, translucent materials are rendered by Bidirectional Surface Scattering Reflectance Distribution Function (BSSRDF). BSSRDF is a model defined by physical concepts such as reflection, absorption, transmission and diffusion when incident on objects and required a large amount of calculation. Therefore, it is inefficient to apply BSSRDF to all objects in real-time rendering. In order to solve this problem, it is necessary to use a lighting model to have a similar effect to BSSRDF. The rendering method of translucent materials based on the Blinn-Phong model suggested by Davit Naskidashvili can render in real time but there is a problem that internal scattering color would not change depending on the color of the lighting. To solve this problem, this research improved the algorithm in order to reflect the lighting color. Also the transmission coefficient was calculated using the refractive index of the material and the Fresnel equation to find a transparency coefficient of the object. By adding the inputted transparency parameter of the object and the transparency coefficient, the finalized internal scattering color and the intensity of the scattering were obtained. As a result, the natural internal scattering rendering was possible according to the lighting color, refractive index, and the transparency. © 2014 International Information Institute.