Rendering - Physically-Based Rendering

Global Illumination-Cornell Light Measurement Laboratory

The Cornell Light Measurement Laboratory

Project Overview

We have established a sophisticated light measurement laboratory with NSF and industry support. We are now able to measure directional-hemispherical diffuse reflectance and specular reflectance as a function of wavelength and incident angle, and the isotropic bidirectional reflectance functions (BRDFs) over a range of incidence and reflection angles and a range of wavelengths. We can also measure spectral radiance from a point source, the spectral radiance of a scene, and surface roughness parameters for physically-based reflectance models [TORR95] [FOO95] [CHEN95].

The ability to measure physical environments radiometrically greatly improves the Center's capacity to carry out controlled experiments and to compare simulations with real-world environments.

Bidirectional reflectance distribution function (BRDF) information measurements are added to the site as they become available in order to make a materials database available to the graphics community.

When the Center began, we started building the light measurement lab at Cornell to assess quantitative differences between actual scenes and rendered simulations of those scenes. Previously, comparisons were based on subjective apearance alone. We have been able to simulate how light scatters off each surface and propagates through the scene, and have verified our results using the Center's measurement facilities. The repercussions of this research are far reaching: the ability to predict exact lighting and color appearance will not only improve visualization accuracy, but also enhance the development of new technology for color printing , digital photography, and image displays.


Center Sites

Cornell

Lead Researchers

Donald Greenberg
Kenneth Torrance
Eric Lafortune

Bibliographic References

[CHEN91]Shenchang Eric Chen, Holly Rushmeier, Gavin Miller, and Douglass Turner. A Progressive Multi-Pass Method for Global Illumination. In Computer Graphics, 25(4), Proceedings, Annual Conference Series, 1991, ACM SIGGRAPH, pp. 165-174.

[FOO95]Sing-Choong Foo and Kenneth Torrance, "Equipment Acquisition for the Light Measurement Laboratory of the Cornell Program of Computer Graphics," PCG-95-5, Program of Computer Graphics Technical Report, Cornell University, September 30, 1995.

[TORR95]Kenneth Torrance, Suthipong Wangpattanasirikul, and Sing-Choong Foo, "A User's Guide to the OL750 Spectral Reflectance Measurement System," PCG-95-1, Program of Computer Graphics Technical Report, Cornell University, February 1, 1995.

Rendering Bibliography

Full Research Bibliography

Web References

Light Measurement Laboratory

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