View Full Version : Final Gather Shading Passes

09 September 2004, 02:14 AM

Does anybody know how I can get the shading FG generates where two surfaces come together out as a seperate pass?

Or would it be better to simulate it using a light dome or similar?

I have a scene that I'm planning to do a print resolution render for that is lit using spots and FG. I'm looking to reduce the amount of rendering time needed, and it sounds like passes are the way to go. I can do shadow passes using lights, Use Background shader and primary visibility, but I can't seem to use the same sort of technique with FG.

Using Maya 5.0.1.



09 September 2004, 03:29 AM
Here is a little project that I am working on right now. Maybe it will help you. I have all the passes I have rendered from maya, that I have composited in shake.

As for your question, I would suggest the Dirtmap shader for mental ray. Look at the dirtmap pass, it is exactly as you are wanting. It renders "dirt" where two surfaces come together. It is technically called an occlusion pass.

and the (close to) Final piece.

P.S. since this is a work in progress, I wouldn't mind any suggestions.

09 September 2004, 03:30 AM
If you type in a name for your Final Gather map, render the scene, then turn off Final Gather Rebuild, you can then apply a lambert shader with full white diffuse shading to your objects and render out a FG pass.

More or less anyway!

Not even XSI 4.0 has a FG pass option, maybe this is something Mental Images needs to address?


09 September 2004, 03:36 AM
Hey looks good DiGiman!

A Dirtmap pass is probably what I'd go for too. Seeing as though you said suggestions are welcome, I think that the car doesn't quite match the angle of the background looks like the car might be tilted slightly down on the side closest to us? The front edge of the bonet looks to inclined or something. It's tough matching angles I know!


09 September 2004, 03:42 AM

thanks, but this is actually a still of an animation. The hummer is in mid turn driving off camera to the right. It is tilted. The perspective should be correct, this was all rendered out of maya, background and all.

09 September 2004, 04:24 AM
damn! when will it happen that some talented will write a shader for that???:shrug:

09 September 2004, 06:05 AM
Wow, I wasn't expecting such fast responses! I'll give the Dirtmap method a go for now.

Digiman: That's exactly what I'm after. Thanks for pointing out the name for the pass also.
Great to see the passes other people are putting into their work too! Can I ask what work you've had to do to that image after those passes?

Jozvex: Is it possible to save the final gather information as a file after the render, or do you have to do it before as you suggested in your post? I think I read somewhere that FG will recalculate if you move the camera. Will it also need to recalculate if you play with visibility / primary visibility of objects / chrome shaders? Thanks also for making your tutorials available. They've been brilliant to study and use.

Thanks for your help!


09 September 2004, 06:41 AM
The hummer is in mid turn driving off camera to the right.

Ohh I see! That makes perfect sense then. Good job on the whole thing!


10 October 2004, 12:12 AM
Hey Digiman

Im curious as to how you have split out these differernt passes in Maya? I know how to do it in Max, but unsure as to the process of how to do it in MR. Or maybe you can help you are the Mental Ray MASSSSTER!!


10 October 2004, 01:49 AM
helo MR DIGIMAN...can i have a tutorial on final gather i just cant get the correct attributes...can i ask for the settings you use in your sample image shown??hope you can grant my request...thanks a lot...gud luck...

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