Department of Computer Science Colloquium
Thursday February 21st 2002 4:15pm
Upson Hall B17
and Modeling the Appearance of Materials
Stanford University - Graphics
has been a fundamental area of study in computer graphics since its inception.
We can approach realism by simulating the physics of how images are
formed, an important part of which is the reflection of light by materials in
the scene. Today the quality of
models for light reflection is in many cases the limiting factor for realism;
current techniques miss subtle but significant aspects of the appearance of real
materials. To build models that
capture these subtleties we must first understand the optical phenomena that
cause them. For this reason,
advanced light reflection models should be motivated by measurements of real
materials. This talk will cover three projects that
involve measuring light reflection for the purpose of developing better models
for computer graphics. I will first
discuss a novel image-based technique that quickly and accurately measures the
angular dependence of light reflection from surfaces.
The technique applies to many materials that cannot be measured by
conventional means, and we used it to make the first measurements of this type
for human skin. I will then present
a new model for light reflection from translucent materials.
The model is based on diffusion, and it was validated against
measurements of several materials. Finally
I will describe an investigation into light scattering by human hair, which
revealed new phenomena related to the internal reflection of light within the
fibers. An analysis of light
scattering from elliptical cylinders explains these new phenomena and also leads
to a practical computational model.
is joint work with Steve Westin, Henrik Wann Jensen, Pat Hanrahan, and others.