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The Bounced z-Buffer for Indirect Visibility

Oliver Nalbach     Tobias Ritschel     Hans-Peter Seidel

MPI Informatik

Abstract

Synthesizing images of animated scenes with indirect illumination and glossy materials at interactive frame rates commonly ignores indirect shadows. In this work we extend a class of indirect lighting algorithms that splat shading to a framebuffer - we demonstrate deep screen space and ambient occlusion volumes - to include indirect visibility. To this end we propose the bounced z-buffer: While a common z-buffered framebuffer, at each pixel, maintains the distance from the closest surface and its radiance along a direction from the camera to that pixel, our representation contains the distance from the closest surface and its radiance after one indirect bounce into a certain other direction. Consequently, with bounced z-buffering, only the splat from the nearest emitter in one direction contributes to each pixel. Importance-sampling the bounced directions according to the product of cosine term and BRDF allows to approximate full shading by a simple sum of neighboring framebuffer pixels.

Materials for Download

Paper (PDF, 43.2 MB) / Paper (low) (PDF, 1 MB)
Supplemental Video (AVI, 79.8 MB)
VMV Presentation Slides (PPTX, 5.9 MB)

Citation

Oliver Nalbach, Tobias Ritschel, Hans-Peter Seidel
The Bounced Z-Buffer for Indirect Visibility
VMV '15: International Workshop on Vision, Modeling and Visualization.

@inproceedings{Nalbach2015,
	author		= {Oliver Nalbach and Tobias Ritschel and Hans-Peter Seidel},
	title		= {The Bounced Z-Buffer for Indirect Visibility},
	booktitle	= {VMV '15: International Workshop on Vision, Modeling and Visualization},
	publisher	= {Eurographics Association},
	year		= {2015}
 }