[Bf-committers] BRDF conversion - Was Farsthary anouncement
Arne Schmitz
arne.schmitz at gmx.net
Thu Feb 12 11:08:56 CET 2009
Am 10.02.2009 um 07:46 schrieb joe:
> The mathematical definition of a BRDF is simple enough, that it seems
> you could wrap specular and diffuse legacy shaders into a blackbox,
> with all the parameters stored internally, not visible to the outside
> world. Sure, it'd suck quite a lot, but what I'm wondering is if
> that'd work better then trying to mathematically map legacy shaders to
> valid BRDF's.
The problem with many legacy materials / BRDFs is, that they are not
true BRDFs. That is they violate some conditions of being a physically
valid BRDF. For example the traditional Phong model is not energy
conserving, i.e. it might create more reflected radiance, than
incoming radiance is produced. With this in mind, I figure you /could/
for example map a legacy BRDF to a 6-dimensional function defined on
spherical harmonics, and make a least squares approximation to a
valid, modern BRDF that is physically sound. You will notice
differences, but it would still be nice. Anyone want to write a paper
about that? :) I think SIGGRAPH Asia deadline is coming up...
Regards,
Arne
--
Dipl.-Inform. Arne Schmitz Phone +49 (0)241 80-21817
Computer Graphics Group Fax +49 (0)241 80-22899
RWTH Aachen University http://www.rwth-graphics.de
Ahornstrasse 55, 52074 Aachen, Germany
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