[Radiance-general] Ambient File and BSDF

[Stephen Wasilewski]

I’m trying to model woven shades using a BSDF from the CGDB.  To get better looking and more accurate results I am using a BRDF as the standing geometry that is based off of a .cal file that greg wrote for metal grating:  https://www.dropbox.com/s/bzo9apzcl4ioika/rollershade.cal?dl=0

when I apply this material to geometry it behaves as expected and cuts off the direct relative to the angle of incidence (which I hope explains this funny test scene I’m using)

image of BRDF shades:  https://www.dropbox.com/s/tlcqqij9rjng5s6/BRDF_mar21_test_test_fc.jpg?dl=0

But this does not give me accurate diffuse values.  So I then put the BRDF as a proxy for the BSDF and get an image like this:
https://www.dropbox.com/s/7k2n38kvn5jp8fg/both_mar21_test_test_fc.jpg?dl=0

My question arises when I look at image without proxy geometry for the BSDF.

First rendered with multiple processes: https://www.dropbox.com/s/1cw56kwevnx9ajt/mt_BSDF_mar21_test_test_fc.jpg?dl=0
And run on a single processor: https://www.dropbox.com/s/pm5q8ikh6kgwh6f/BSDF_mar21_test_test_fc.jpg?dl=0

or to view it more starkly, the difference between the BSDF alone and with proxy:

bsdf - proxy: https://www.dropbox.com/s/hf2vy2wfpss7gr0/BSDFboth_fc.jpg?dl=0
proxy - bsdf: https://www.dropbox.com/s/di8duoz2gob0ams/bothBSDF_fc.jpg?dl=0

There is a major change in the ambient values once the rendering gets to the window (which is why the band is horizontal in the single process run and vertical in the multiple process run.  I ran these using rad so there is an overture calculation.  Anyone have an idea as to what is going on?

Stephen Wasilewski
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