The Bounced z-Buffer for Indirect Visibility

Oliver Nalbach     Tobias Ritschel     Hans-Peter Seidel

MPI Informatik

Screen space methods for indirect illumination not only underestimate effects of invisible geometry but also routinely ignore visibility which is added by our approach.

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

Citation

Oliver Nalbach, Tobias Ritschel, Hans-Peter Seidel
The Bounced z-Buffer for Indirect Visibility
Proc. VMV 2015

@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}
 }