GPU Pro 6

3

VI

Smooth Probabilistic

Ambient Occlusion

for Volume Rendering

Thomas Kroes, Dirk Schut, and Elmar Eisemann

3.1 Introduction

Ambient occlusion [Zhukov et al. 98] is a compelling approach to improve depth

and shape perception [Lindemann and Ropinski 11, Langer and B¨ulthoff 99],

to give the illusion of global illumination, and to efficiently approximate low-

frequency outdoor lighting. In principle, ambient occlusion computes the light

accessibility of a point, i.e., it measures how much a point is exposed to its sur-

rounding environment.

An efficient and often-used version of ambient occlusion is screen-space am-

bient occlusion [Kajalin 09]. It uses the