A Method for Fast Rendering of Caustics from Refraction by Transparent Objects

Kei IWASAKI  Fujiichi YOSHIMOTO  Yoshinori DOBASHI  Tomoyuki NISHITA  

IEICE TRANSACTIONS on Information and Systems   Vol.E88-D   No.5   pp.904-911
Publication Date: 2005/05/01
Online ISSN: 
DOI: 10.1093/ietisy/e88-d.5.904
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Section on Cyberworlds)
caustics,  global illumination,  real-time rendering,  graphics hardware,  

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Caustics are patterns of light focused by reflective or refractive objects. Because of their visually fascinating patterns, several methods have been developed to render caustics. We propose a method for the quick rendering of caustics formed by refracted and converged light through transparent objects. First, in the preprocess, we calculate sampling rays incident on each vertex of the object, and trace the rays until they leave the object taking refraction into account. The position and direction of each ray that finally transmits the transparent object are obtained and stored in a lookup table. Next, in the rendering process, when the object is illuminated, the positions and directions of the rays leaving the object are calculated using the lookup table. This makes it possible to render refractive caustics due to transparent objects at interactive frame rates, allowing us to change the light position and direction, and translate and rotate the object.