[Radiance-general] Non symmetrical BSDF from symmetrical geometry

[Greg Ward]

Hi Marouane,

Your fabric has very thin lines in it, which may be difficult to integrate with the normal sampling density.  Since the pattern seems to repeat, I recommend that you restrict your sampling area using the genBSDF -dim option to set a bounding box.  Looking at your file, the pattern appears to repeat every 42 mm.  You can set a square area near the middle of your fabric with this diameter like so:

	genBSDF +f +b -geom millimeter -dim 1500 1542 1500 1542 -1 0 0.rad > 0.xml

This seems to produce something reasonably symmetric when I try it.

Cheers,
-Greg

> From: Marouane.Boudhaim at ise.fraunhofer.de
> Date: June 23, 2017 7:25:25 AM PDT
> 
> Hi all, 
> 
> 
> I am trying to generate a BSDF of a profile angle symmetrical textile. The problem is that the BSDF is supposed to be left and right symmetric (as is the geometry). In practice the BSDF doesn't look left/right symmetric in BSDFviewer. Is it a problem due to the ray-tracing calculation with many small objects or did I mess up something? here is the command I have run to generate the BSDF : 
> 
> genBSDF +f +b -geom millimeter -n 5 0.rad > 0.xml 
> 
> I attach the 0.rad file used to the email. Thanks in advance for your help! 
> 
> Sincerely, 
> Marouane Boudhaim. 
>