genBSDF and BDSF viewer


Hi all
Im new to radinace and I want to calculate the BSDF of a CFS. I wonder if the surface normal of the glazing system is important to genBSDF ? also i use BSDF as the material for the slats which also has an up direction, and i wonder if this also important to genbsdf? also after creating the slats and glazing how can i be sure my orientation is correct ?

when i created the bsdf of the whole CFS, the bsdf viewer does not show any data at end (probably there is an error but i have no idea where did i go wrong coz it works for other correct BSDF files), I would appreciate your help in this too or a bit of your invaluable experience.


Hi Amin,
For your second question, I’d recommend opening your BSDF file and one of the working BSDF files in a text editor to do a rough comparison. If you can’t spot major differences, go ahead and email it to me directly (mcneil.andrew at gmail dot com). I can have a look.


The Radiance “glass” type is two-sided, so its surface normal orientation is not important. For your BSDF material, the “up” direction matters if it is anisotropic, but not if it is isotropic. You still need to give an orientation, however. I don’t know if this answers your question.

The “pkgBSDF” is sometimes helpful in creating surfaces from genBSDF output for rendering, so have a look at that. In general, genBSDF associates the Y-axis with the final “up” direction, as explained in the man page.


Thnaks for your feedbacks. my BSDFviewer works properly now. Ive read Andy Mcneil tutorial for genBSDF, and after some tests it seems one of the most important options is -dim and setting the boundary. I wonder if its better to take the whole CFS or just a small part of it as Andy discussed in his tutorial. Also if there is more examples or tutorials on genBSDF could you please share them or send me the links ?