iCheat: A Representation for Artistic Control of Indirect Cinematic Lighting

Juraj Obert Jaroslav Křivánek Fabio Pellacini Daniel Sýkora Sumanta Pattanaik
Computer Graphics Forum (Proceedings of EGSR 2008) 27(4):1217-1223, 2008
Thanks to an increase in rendering efficiency, indirect illumination has recently begun to be integrated in cinematic lighting design, an application where physical accuracy is less important than careful control of scene appearance. This paper presents a comprehensive, efficient, and intuitive representation for artistic control of indirect illumination. We encode user's adjustments to indirect lighting as scale and offset coefficients of the transfer operator. We take advantage of the nature of indirect illumination and of the edits themselves to efficiently sample and compress them. A major benefit of this sampled representation, compared to encoding adjustments as procedural shaders, is the renderer-independence. This allowed us to easily implement several tools to produce our final images: an interactive relighting engine to view adjustments, a painting interface to define them, and a final renderer to render high quality results. We demonstrate edits to scenes with diffuse and glossy surfaces and animation.