Ames Laboratory, Department of Energy, ISU, Ames, Iowa

SLALOM: A New Computer Graphics Method


Solve the equations that describe the appearance of a virtual scene so that it can then be viewed from any position. Allow no "guesses." Use a method that is physically correct and mathematically rigorous.


The Scalable Computing Laboratory (SCL), a part of the Applied Mathematical Sciences Program at Ames Laboratory on the Iowa State University campus, has invented the first computer graphics method, SLALOM (Scalable, Language-independent, Ames Laboratory, One-minute Measurement), that can guarantee a range for the correct appearance. Most graphics methods make guesses about shadows and other lighting effects in a scene, hand-doctoring the output to make it look more realistic. SLALOM puts an upper and lower bound on the amount of light given off by every surface and "squeezes" the bounds so the answer Improves to whatever accuracy is needed.

The new method developed by the SCL also allows parallel processing to be used; older methods did not. Each processor can work with a subset of the scene, working asynchronously with the best available information about the rest of the scene. Each doubling of the processing power improves the accuracy of the answer by about 40%.


The SLALOM method can be used for Virtual Reality, for architectural prototyping (leading to more efficient use of artificial and natural lighting in interiors), and for scientific visualizations with unprecedented realism. Once SLALOM has reached the necessary accuracy, one can "navigate" through the room or other geometry without recalculation; hence, it solves the biggest obstacle to the optical part of Virtual Reality simulations.

Because SLALOM permits parallel processing, it can make use of the newer massively -parallel computer designs. This opens up a new application area for commercial parallel processing, since it provides higher performance and more detailed simulations at lower cost.

Future Work

The SCL will extend its method to a variety of surface properties, taking into account polarization of light, reflectance scattering that depends on color, even the subtle effects of fluorescence. The SLALOM program will be modified to take its input from standard graphics software packages to move it from a laboratory tool to the level of marketable, off-the-shelf software for general use.


John Gustafson and Quinn Snell


SLALOM stands for Scalable, Language-independent, Ames Laboratory One-minute Measurement, because it was created to measure how much work a computer could do in one minute. Its use as a benchmark has been superceded by the much simpler HINT, but SLALOM continues to be valuable as a unique computer graphics tool. It may be the first case of a computer benchmark turning into a real application program, instead of the other way around!

View SLALOM Summary

John Gustafson
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