A Virtual Light Field Approach to Global Illumination

Mel Slater, Jesper Mortensen, Pankaj Khanna, Insu Yu

Paper 144 - submitted

Abstract:
This paper describes an algorithm that provides real-time walkthrough for globally illuminated scenes that contain mixtures of ideal diffuse and specular surfaces. A type of light field data structure is used for propagating radiance outward from light emitters through the scene, accounting for any kind of L(S|D)* light path. The light field employed is constructed by choosing a regular point subdivision over a hemisphere, to give a set of directions, and then corresponding to each direction there is a rectangular grid of parallel rays. Each rectangular grid of rays is further subdivided into rectangular tiles, such that each tile references a sequence of 2D images containing colour values corresponding to the outgoing radiances of surfaces intersected by the rays belonging to that tile. This structure is then used for final image rendering. Propagation times can be very long and the memory requirements very high. This algorithm, however, offers a global illumination solution for real-time walkthrough even on a single processor.

Media:
The paper final submission (2.7MB doc)
The paper final submission (2.7MB pdf)
Powerpoint presentation given at CGI'04, Greece 17th of June 2004 by Jesper Mortensen (1.8MB .ppt)

The videos (9.8MB zipfile containing all videos, resolution 256*256, codec mpeg1). All renderings were carried out on a dual-xeon 2.8GHz machine, with 3GB memory and nVIDIA FX5900 ultra.

Separate videos, please download to disk before playing:
Cornell Room (4.5MB)
Smits & Jensen Caustic test scene (1.8MB)
Office Scene (Real-Time Ray Tracing) (3.6MB)
Office Scene (Progressive Rendering) (2.7MB)

Colour images from final paper:
Figure 4 [a-d]:

Figure 6 [a,b]

Other images:
Rendering types:
[1] Full VLF.
[2] VLF specular and hardware texture mapped diffuse.
[3] Ray traced specular and hardware texture mapped diffuse.
[4] Fully ray traced with diffuse map lookups.
          
[1]                [2]                [3]                [4]

Complexity test scene:

Cornell type scene (with mirror):

Original global illumination benchmark rendering:

Alternative view of caustic ring scene:

Alternative views of office scene: