PDA

View Full Version : How to Cache Ambient Occlusion and Bent Normals in Mental Ray

avedis
08-15-2005, 06:16 AM
Hi Everyone

I've been using Prman for a while, but have decided to play around with mental ray in maya 6.5 a lot more lately. I've run into two things that have stumped me, How do you cache out a ambient occlusion and bent normal pass to a file like you can in renderman. The only solution I have found is bakeing the occlusion into a map. Is there a way to do a bent normals pass, and pipe that back into a shader in order to do a proper ambient light pass?

Thanks

Avedis
1armedScissor
08-16-2005, 02:52 AM
do a search in maya docs on ambient occlusion and it'll tell you everything you need to know. cheers!
rendermaniac
08-18-2005, 11:28 PM
You'd probably use a lightmap shader to bake this out - like the sss_fast shaders.

Simon
avedis
08-18-2005, 11:31 PM
Hello

Thanks for the info guys, It's to bad mental ray doesn't have some of the same features as renderman does, but who knows probably will be implemented soon enough.

Thanks

Avedis
1armedScissor
08-19-2005, 03:33 AM
It's all there, just a matter of searching the docs on how to do it. Alot of the things you can do in Renderman you can do in mental ray. It's just done differently.
tweeeker
08-20-2005, 10:21 AM
It's all there, just a matter of searching the docs on how to do it. Alot of the things you can do in Renderman you can do in mental ray. It's just done differently.

So mental ray has a generalised pointcloud/3dtexture format like prman? I'm aware of the kdtree stuff in mr, but thats quite different to the brickmap stuff in prman. My understanding was that mr currently has no (out the box) brickmap style functionality, but I'd love any pointers if I'm wrong.

cheers

T
1armedScissor
08-20-2005, 06:32 PM
read the post again, at no point did I say mentalray can do "everything" that renderman can. Easy there turbo. lol I said "alot" of things. Each renderer will do some things that others can't that's just common sense.
rendermaniac
08-20-2005, 11:36 PM
So mental ray has a generalised pointcloud/3dtexture format like prman? I'm aware of the kdtree stuff in mr, but thats quite different to the brickmap stuff in prman. My understanding was that mr currently has no (out the box) brickmap style functionality, but I'd love any pointers if I'm wrong.

cheers

T

It's a shame pointclouds/brickmaps aren't general enough. Two things missing from it are a way to query a point and gather all the points in a certain radius, and to raytrace against a pointcloud rather than geometry (which I guess you could do with the former by raymarching through it).

Simon
tweeeker
08-24-2005, 10:17 PM
ooga booga - I think I asked a valid question, no need to bite by head off man:eek: Anyways I presume to bake bent normals from mib_amb_occlusion it's necessary to to use a lightmap shader? I too would be very interested in any guidance as to how to achieve this using the maya hypershade (the docs don't seem to go into much detail on how to configure lightmap shaders).

Simon - I agree that point clouds should be more flexible, although it is possible to implement your first request as a dso. Personally I'm hoping it will be possible to raytrace brickmaps (rather than pointclouds) in prman 13. Some initial reports claiming that prman 13 will be able to render brickmaps directly does look promising.

T
CGTalk Moderation
08-24-2005, 10:17 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.