Hi,
With rtrace -oN, what is the convention that Radiance uses to determine which direction the normal vector is returned as facing.
I was getting confused in my app as I was tracing rays from above a horizontal plane, and didn't realise that the normal of intersection on the plane was being returned as [0 0 -1] instead of the [0 0 1] as I had assumed.
What is the general rule for which direction the normal is returned in, so I can account for it?
Thanks,
Chris
What is the general rule for which direction the normal is returned in, so I can account for it?
Hmm, seems that the normal for that polygon is facing down. Perhaps that affects it?
Chris
Hi Chris,
Yes, I think -oN returns the surface's unperturbed normal, which means whatever direction it has in the actual geometry is the one you get. If you use the -on option instead, which takes longer and may involve tracing additional rays, you'll get the perturbed normal that includes textures and any reorientation for the material type. I think this would fix your problem, and wouldn't cost much since there are no light sources or shading going on in your single polygon scene, anyway.
-Greg
From: Christopher Kings-Lynne <[email protected]>
Date: January 21, 2005 7:13:08 AM PSTWhat is the general rule for which direction the normal is returned in, so I can account for it?
Hmm, seems that the normal for that polygon is facing down. Perhaps that affects it?
Chris