Direct Visualization of Real-World Light Transport

Matthias B. Hullin¹           Martin Fuchs¹           Boris Ajdin¹
Ivo Ihrke²           Hans-Peter Seidel¹           Hendrik P. A. Lensch¹

¹MPI Informatik      ²University of British Columbia

Setup for light transport visualization
Ingredients for visualization of light transport.
Water tank with fluorescent dye, green laser pointer,
and some other optional stuff.

Abstract

Light transport in complex scenes with possibly intricate optical properties is difficult to grasp intuitively. The study of light transport has so far mainly been conducted by indirect observations. Cameras or human observers typically only sense the radiance reflected from a scene, i.e. the light directly emitted or reflected from the last bounce of a possibly much longer light path.
Models for the propagation of light, however, typically assume light waves or rays, concepts which so far have been communicated in an abstract way using formulas or sketches. In this paper, we propose the use of fluorescent fluids for direct visualization of light transport in the real world. In the fluorescent fluid the traces of light become visible as a small fraction of the energy transported along the ray is scattered out towards the viewer. We demonstrate this visualization for direct illumination effects such as reflections and refractions at various surfaces, as well as for global effects such as subsurface light transport in translucent material, caustics, or interreflections. As this allows for the inspection of entire light paths, rather than the last scattering event, we believe that this novel visualization can help to intuitively explain the phenomena of light transport to students and experts alike.

VMV 2008 Paper

Read Full Paper (PDF, 16 MB)

Additional Material

Material for presentations
Feel free to use this material in your lectures, talks, etc.

Bibliography

Matthias B. Hullin, Martin Fuchs, Boris Ajdin, Ivo Ihrke, Hans-Peter Seidel, Hendrik P. A. Lensch, "Direct Visualization of Real-World Light Transport" , Proceedings of VMV 2008, Konstanz, Germany, 2008.