Effects of absorption and scattering values of liquids on global illumination

Abstract

In Global Illumination, calculating absorption and scattering values of transparent or semitransparent materials is one of the most difficult phenomena. Absorption and scattering values affect indirect illumination. This phenomenon is often overlooked in realistic image processing software. When an absorption or scattering coefficient is not input for transparent or semi-transparent materials, the global illumination values do not change. In this study, an experiment was planned to see the effects of absorption and scattering values of liquids on spherical illumination. In the experiment, different liquids were placed in a 55 cm Cornell box, and the illuminance values on the surfaces of the Cornell box were measured for each liquid. The same scene was created with digital image synthesis software. Afterward, the luminance values in the real model and the virtual image were compared. This study proposes adding an absorption and scattering parameter to realistic image synthesis software for transparent and semi-transparent materials. This parameter was prepared with the Open Shading Language (OSL) developed by Sony Imageworks. In this way, the luminance values of the Cornell box in real and digital images are very close to each other.