View Full Version : BRDF Question: What does 'Save Lights in Scene' do?

12-09-2003, 08:37 AM
This little checkbox at the top of my BRDF panel is confounding me... I don't understand what it's usefulness is.

Anyone, anyone.... Beuller?

So, what does; 'Save Lights in Scene' do for me when using BRDF? I've searched the manual (paper and pdf). I've searched the forum.

Does anyone know the answer to my quest (ion)?



12-09-2003, 01:23 PM
It will save some extra info in the scene file which is used for the include/ exclude behavior as well as a random number for anisotropy.


12-09-2003, 01:31 PM
So, what would be a real reason that I would use this feature? And what's the purpose of a random number for anistropy?

Sounds almost useless.


12-10-2003, 05:27 AM
Nope, it's not useless.

a) BRDF allows light inclusion/ exclusion on a per surface basis as opposed to per object in Layout, so why not take advantage of it?

b) Anisotropy in CG is simulated using the assumption of microscopic "scratches" on surfaces. Think of this of as a micro bump map. This one uses a random number for creating its noise. If you do for instance a network render on different machines, frames would flicker since every machine would use it's own random number. That#s why it's important to keep track of such things.


12-10-2003, 07:55 AM
I'm still fuzzy on the save lights thing... does it generate an actual file... is it just maintaining applied lighting information in the shader...

BUT, great explanation of the random number bit... THAT I totally get. I've heard of the flickering issue before although I've never been troubled by it, lacking a successfull implentation of SN and all.

Thanks for you input though.