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Active Member
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Registered: ‎08-28-2006

workflow renderman

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02-22-2007 10:56 AM
doe's anybody have a workflow for getting successful displacments working with renderman they would be kind enough to share.
:smileyhappy:
Valued Contributor
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Registered: ‎02-22-2007

Re: workflow renderman

02-23-2007 03:29 AM in reply to: craigls
There's actually nothing to it, I'm using 32 bit, no need to offset the map, since it's generated with it's middlepoint on zero, in your texture file, be sure to use radial-bspline filtering, and in your displacement node set your displacement on distance should be 1, although I've come upon occasions where that wasn't correct, might be caused by scale of the object but I'm not sure, the bound I think should work at 1.1, this might be the actual inworld distance in mudbox, I have to check that.

What is it you needed anyway, what renderman are you using (for maya or pro), what specifics do you need?
Valued Contributor
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Registered: ‎08-24-2006

Re: workflow renderman

02-23-2007 03:46 AM in reply to: craigls
I don't know exactly on what renderman you think, but here is my basic workflow with pixar rat and maya... (and I am not an expert :smileyhappy:

first you have to subdivide your low poly, I use pixar's subdivision scheme, but I suppose you can get the same results using maya's, or just smoothing your poly mesh, however I prefer the first way. I use catmull'n'clark subd's scheme.
After that make an ensemble node and plug surface and displacement shader in appropriate slots. Simple displacement will do the job, but you can play also with combined. Plug the file into the displacement (be sure to use txmake comm. to convert tiff to pixar's tex format), set the channels u want to use, and filtering (radial-bspline is optimized for displacement maps they say). Adjust displacement bounds in displacement shader, adjust kb attribute (displacement strength), attach ensemble to your geometry and voila... it should work... Personally I found values between .5 and 1 for kb working in most cases, but you will have to experiment with that...
here is the sample of something I am working on:
http://djordje.petrovic.googlepages.com/pic_01.jpg

for mudbox baker settings, well I use 32bit float maps (tiff) with keep zero as midd gray OFF, everything else is on default, but I attached capture of baker window in case you need it...
http://djordje.petrovic.googlepages.com/baker.jpg

hope this helped a bit.

good luck

dj.
Active Contributor
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Registered: ‎12-22-2006

Re: workflow renderman

03-22-2007 01:02 AM in reply to: craigls
hello RAT users

i've just extracted a 32 bit displacement map from mudbox and tried to render it in PRman. but apparently, black in renderman means 0, and 1 means white. there are a ton of black spots from the displacement map i got out from mudbox's baker. and all the black areas of the model aren't displacing correctly.

anyone know how to fix this problem? i tried both keep zero as grey checked and unchecked, but both displacement maps have black areas, and mis-renders those areas thinking it has no info there.

my workflow is basically what the rest of u have mentioned so far. let me know if u guys want to know certain specifics

thx in advance!

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Registered: ‎12-22-2006

Re: workflow renderman

03-22-2007 01:09 AM in reply to: craigls
just to add some more tips along with this thread:

- in the imagefile texture editor, make sure precision is selected to float if your using 32 bit displacement map

- Red Channel, so the image can show up in the nodes

- make sure displacement bound is always larger than kb, around 2x is a good rule of thumb.
Contributor
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Registered: ‎02-28-2007

Re: workflow renderman

05-08-2007 06:08 AM in reply to: craigls
i neither smooth nor subdivide my mesh.(doesn't mean that you don't have to or it is unnecesery), but the rest is just like djorzgul has said.
it is so simple and 1- 2- 3 in rat.

what you render in 2 minutes with mentalray is, 15 seconds in renderman. and the level of detail is uncomparable. what you see in mudbox is there in your prman render in means of tiny details and such a short time.
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Registered: ‎08-24-2006

Re: workflow renderman

05-08-2007 06:42 AM in reply to: craigls
strange (I don't say that you're wrong, I believe I do something wrong..) but every time I apply displacement on model without subdividing it (or smoothing) I get strange faceting and cracks all over the model...
so if you have any tip, I'd appreciate... :smileyhappy:
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Registered: ‎02-28-2007

Re: workflow renderman

05-08-2007 07:38 AM in reply to: craigls
i just extract 4096x4096 (settings good) displacement map. and export my level_1 mesh(this is kinda smoothing though.). in maya i only soften edges. and kb to 1-1,5(to your taste) and the rest is just like yours. it works on me.

cheers.
Valued Contributor
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Registered: ‎08-24-2006

Re: workflow renderman

05-14-2007 01:32 PM in reply to: craigls
cool, I 'll try that.. thanks for the tip...
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Registered: ‎04-07-2006

Re: workflow renderman

05-20-2007 03:08 AM in reply to: craigls
I just posted a question about whether to catmull- subdivide the Maya mesh once in Maya before importing to Zbrush ? Would this help, or does Mudbox do a correct catmull subdivision anyway for us ?

We have an in-house catmull plugin that will correctly smooth a mesh with UVs to match what prman will do at render time, a lot of the time you want to make sure that what you paint in 3D will look perfect when prman subdivides it in the renderer.

To get inch-perfect results you need to make sure the UVs are smoothed, but corners preserved. prman does NOT smooth the same way as Maya so don't rely on a Maya smooth node to match what a renderman one will eventually do