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DIMO
05-30-2006, 12:59 PM
Hi,

First of all some links to get you into the topic of measured BRDFs:
http://www.cs.princeton.edu/gfx/proj/brdf/fig10/
http://web.cs.wpi.edu/~emmanuel/courses/cs563/write_ups/zackw_measurement.html (http://web.cs.wpi.edu/%7Eemmanuel/courses/cs563/write_ups/zackw_measurement.html)
http://www.virtualcinematography.org/publications/acrobat/BRDF-s2003.pdf


has anybody here already worked with measured BRDFs? I read several papers about it and I think setting up a shader is not the problem but acquiring the measurements. How hard and expensive is it to set up a reflectometer?
I know that Spheron offers a measurement service, but they only support Maya / mental ray.
Are there other companys that offer brdf measurement?

Best Regards,

Dieter

playmesumch00ns
06-01-2006, 11:44 AM
One of the papers (I think it was Lafortune et al) I've read describes how they just measured the brdf from photographs using a normal digital camera and moving a standard light source around the object. It obviously helps if the object you're trying to meaure is cylindrical, if it's a fabric or a paint you can wrap/coat a cylinder in the material in order to measure it.

rendermaniac
06-01-2006, 04:05 PM
I am guessing you mean this one?

http://www.graphics.cornell.edu/pubs/1999/MWL+99c.html

The tircky parts are that you need to know about the camera, light and surface positions. And to do that you need to model the scene from tracking data. That's the bit that is hard work.

Simon

DIMO
06-02-2006, 06:33 PM
Hi,

just learned about BTF measurement, which seems even more exciting. I also got in contact with a german university here that can do BTF measurements. I already started to implement a VRay shader that will use measured BRDFs data from one of the siggraph papers above to test the whole thing out. It's a long way to go, but I am pretty sure I can pull this off.
But I am still searching for someone who has experience with measured BRDFs. Is it worth the trouble?

Best Regards,

Dieter

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