maya mentalray final gather 3+ bounces possible?
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So I'm really trying to avoid using photons on our current project due baking time constraints has anyone figured out how to get more than 2 bounces of indirect light out of maya final gather? There is that option to turn on secondary diffuse bounces but that's it no option to do 3 or 4 bounces.
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in the outliner, right click,, uncheck SHOW DAG OPTIONS ONLY, then find the midefault node and click on it, now in the attribute editor you should see more final gather options including Sec bounces.
But as Glib mentions id dont know if this is a solution to your problem.
copain I found that tutorial about the secret midefault node but I think in maya 2008 as far as I know you can only add one extra bounce, which is also available in the final gather options window under render globals.
Any ways I think I've found a solution in 2008, I wanted my skydome to emit bounces and because it's not emitting light there was no bounces coming from it, so I'll try emitting photons from the sky and direction light although this is mega slow compared to just emitting 4 bounces from fg in 2009.
That's where the portal light comes in handy, it samples the outside environment and converts it to direct light through the portal. Check it out.
This made me curious and I ran a few quick tests, for me GI + FG with 5 photon bounces was significantly faster than straight FG with 2 bounces (second bounces checked on).
Can you post your test scene so I could take a crack at that? I was just working with a really hastily made mockup.
Glib are you using GI + FG and emitting photons from your sky and directional light, if not all that's happening by turning on GI is you are disabling secondary diffuse bounces. Sorry can't post the scene I'm lighting a large outdoor environment for work, but here is a good example. Make a white plane with a red cube in the center make sure your shaders diffuse values are set to one rather than 0.8?. Make the mental ray skydome node under render globals and set type to texture rather than image. Change it's colour to white or what ever. Turn on FG and render. You will get something similar to ambient occlusion and your red cube will not be bouncing red light onto the white plane. Turn on secondary diffuse bounces in maya 2008 if you're in 2009 turn on secondary diffuse bounces to 1. Render, note the red cube now emits colour transfer onto the white plane. Now turn on GI in render globals rerender. Now it's back to standard FG again, unless there is a light source in the scene but since the sky is not actually emitting light in this case there is no colour tranfer. So you you can turn on photon emission from the sky and now the render will take longer as it has to do the photon transmission step. Unless I'm misreading your post in which case I apologize for this super long text I just wrote.
Emitting 10,000,000 photons takes maybe 20 seconds on my computer (which is far from being a powerhouse). When using FG + GI, the idea is that you keep your accuracy low in the GI settings as well as the FG. The GI chooses the colors and locations of the photon strikes, then the FG is just there to blend and smooth the result. Using straight FG with secondary diffuse bounces is a very slow process since it was never really designed for that AFAIK. They give you the option, but GI is still the ideal solution I think.
I'll put together that scene and run a couple tests later today.
There are shaders which output a color-bounce as well as occlusion. I used to use a few on the lamrug.org site, but it appears they've gotten rid of them (or at least I can't find them there anymore).
This looks like it might be a newer incarnation of that: http://www.highend3d.com/maya/downloads/shaders/Ambient-Occlusion---Fake-FG-for-Maya-4460.html
Also for the AO you should definitely look at the new mia_material which has built in AO.
Or you could add a AO pass using renderlayers and the AO preset.