Real-time refraction through deformable objects

Light refraction is an important optical phenomenon whose simulation greatly contributes to the realism of synthesized images. Although ray tracing can correctly simulate light refraction, doing it in real time still remains a challenge. This work presents an image-space technique to simulate the refraction of distant environments in real time. Contrary to previous approaches for interactive refraction at multiple interfaces, the proposed technique does not require any preprocessing. As a result, it can be directly applied to objects undergoing shape deformations, which is a common and important feature for character animation in computer games and movies. Our approach is general in the sense that it can be used with any object representation that can be rasterized on a programmable GPU. It is based on an efficient ray-intersection procedure performed against a dynamic depth map and carried out in 2D texture space. We demonstrate the effectiveness of our approach by simulating refractions through animated characters composed of several hundred thousand polygons in real time.