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Master's thesis | @MastersThesis{Annen:SHG:2004, ... | Masterarbeit

Annen, Thomas

Radiance Transfer Using Spherical Harmonic Gradients

Universität des Saarlandes, September, 2004

Spherical harmonics are often used for compact description of incident radiance in low-frequency but distant
lighting environments. For interaction with nearby emitters, computing the incident radiance at the center of an
object only is not sufficient. Previous techniques then require expensive sampling of the incident radiance field at
many points distributed over the object. Our technique alleviates this costly requirement using a first-order Taylor
expansion of the spherical-harmonic lighting coefficients around a point. We propose an interpolation scheme
based on these gradients requiring far fewer samples (one is often sufficient). We show that the gradient of the
incident-radiance spherical harmonics can be computed for little additional cost compared to the coefficients
alone. We introduce a semi-analytical formula to calculate this gradient at run-time and describe how a simple
vertex shader can interpolate the shading. The interpolated representation of the incident radiance can be used
with any low-frequency light-transfer technique.

Color, Shading, Shadowing and Texture
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Completed
28
September
2004
Max-Planck-Institut für Informatik
Computer Graphics Group
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BibTeX Entry:
@MASTERSTHESIS{Annen:SHG:2004,
AUTHOR = {Annen, Thomas},
TITLE = {Radiance Transfer Using Spherical Harmonic Gradients},
SCHOOL = {Universit{\"a}t des Saarlandes},
YEAR = {2004},
TYPE = {Master's thesis}
MONTH = {September},
}





Entry last modified by Thomas Annen, 09/28/2004
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Editor(s)
Thomas Annen
Created
09/28/2004 11:06:34 AM
Revision
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Editor
Thomas Annen



Edit Date
28.09.2004 11:11:28