Preparing for zbrush, a model to be brought back to maya

# 1 01-01-2008 , 10:16 AM

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Preparing for zbrush, a model to be brought back to maya

About to sculpt a model seriously for the first time. It will be animated afterwards. Some questions:

1) Is there anything to be aware of in terms of the skinning of the model - should I be careful of the maximum amount that I move any verts etc - or is it safe to assume that the displaced model will animate well (if the base mesh does already)?

2) When I make blend shapes in Maya for facial expressions etc will the displaced model follow these without artefacting?

3) How would you texture a model that will be displaced? Given that the uv map you use as a guide will not reflect the finished result and will be missing some details?

4) As your base mesh to use when animating in maya, would you use your original base mesh, or export and use the level 1 mesh from zbrush?

5) Zbrush only recognize 1 uv set; can I later add more sets to the model in maya?

I know this isn't a zbrush forum, but many folk here use it and it's a fast moving forum.

thanks,

gubar

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# 2 01-01-2008 , 11:01 AM

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Join Date: May 2005

Location: Manchester Uk

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Hi Gubar

One of the first things I would say is dont try to sculpt a model that had any rigging/skinning or blend shapes on it, your pretty much asking for trouble, use the standsrd pipeling of modeling, texturing, rigging then rendering.

The main thing being is that once you import into Zbrush and sculpt it will move the original geo, pretty much no matter what.

What I do is get a base mesh thats looking like you want then import this into Z (no UV maps) then sculpt, once your happy with that export the level 1 mesh back into maya then UV and use this as a morph target to overide the Uv mesh then texture in PS (if you want to use poly painting in Z then just poly paint prior to making the morph target and uv mapping then transfer the maps to the UV space.

As for the question regarding UV maps and the multiples, if your sculpting Z dosent care if it has maps or not, although as the base level geo changes so will your maps, so your probably best off either not bothering with the UVs when sculpting or if youve already done them they will probably need a tweek, if you want you can add multiple maps to Z and render the displacements, theres a tutorial on the Zbrush wiki that goes into this.

"No pressure, no diamonds" Thomas Carlyle

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# 3 01-01-2008 , 11:18 AM

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Join Date: Mar 2007

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Hi gster,

thanks for the post. I haven't painted weights yet, I am following the usual pipeline... just finding it hard to get my head around whether, once you've sculpted, the displaced mesh will accurately follow the animated base mesh. I just wondered whether I had to take any precautions.

Re Uvs and morph targets - once you have the model ready to sculpt, you save a morph target on the level 1 mesh, then take the map from the highest - is that correct? Think that's what I done when I tried normal mapping a while back.

As for multiple maps... I think I can get away with adding more later. As long as the displacement is assigned to the original (which is the one that it'll match) I should be ok, fingers crossed.

Anyway, thanks again, if you or anyone else has anything else they can add all the better.

cheers,

gubar

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# 4 02-01-2008 , 05:48 AM

Lead Modeler - Framestore
Join Date: Feb 2003

Location: UK

Posts: 6,287

Interesting Questions.

Personally speaking, I'd do the uvs and main color texture before going into Zbrush unless Im doing the texture in zb of course.

Rig it all after, if not you can always add blends to a rig after as long as you create them as a parallel shape, and not in default mode, see the options for this in maya.

Your textures will still fit back in maya after some sculpting but depending on how extreme you pull the mesh about in zb some tweaks may be needed back in maya, but usually a hit of th relax button should cure them. Also rememeber you can sculpt in zb with a texture 'on' so you can see whats happening while you sculpt and have the best of both worlds.

With regard to blendshapes. Create them all at the lowest or manageable resolution first in Maya. Then you could take them into ZB and add detail to them after then export dis maps for each shape. Then once back in maya you could set up the displacements maps to coincide with your animation, basically key them at specific places to match the appropriate blend shapes.

Also be aware that regardless of the mesh from maya to ZB, as gster says it will differ and move the geo even very slightly, so its always best to run all your shapes thru Zb even if you dont sculpt them all.

I just wanna add that Ive just this week run 30+ blendshapes thru zb and back into maya. . Some shapes are more subtle than others, but look nice all the same. I have two sets of shapes: one hi rez and one low res. The hi rez have the details on and the low rez are there for purely base mesh target creation. The Hi rez mesh has 20k polys and looks very nice with the shapes moving about.

Im not using displacements as the shapes look pretty damn cool on export and also I find dis maps and maya STILL very temperamental when it comes to render times so its worth checking this option out too.

Optimise your work flow to what suits you best, I hope some of these options will help you out. Have a play and find whats best for your project.

I'll post up a grab of my shapes later

cheers
Jay

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# 5 02-01-2008 , 09:08 AM

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Thanks for the detailed response Jay. Using different displacements maps - that sounds like a complex (but thorough) method. Is it necessary in your experience? Given that the blend shapes will be a smile, frown, a bicep expansion etc - nothing that will majority deform the base mesh?

I was thinking (hoping) that with these kind of deformations the displacement map may just work without any artifacting... also, if you start to key displacement maps you then have the question of when to key from one map to another, and will that occur without a noticeable jump?

Think the best thing is to just try it out... so I'll have some goes this weekend and post back.

thanks again,

gubar

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# 6 02-01-2008 , 02:50 PM

Lead Modeler - Framestore
Join Date: Feb 2003

Location: UK

Posts: 6,287

Hey gubar

No probs mate.

The method with the dis maps is thorough indeed but I meant it only as another suggestion. I am due to use it myself very soon in a production. Its been one of those methods that has been used in the industry for a while, and if I recall theres something very similar in a chapter on an ALIAS dvd on hypereal facial setup.

The method isnt a necessary one but one that came to mind. Im not an expert on animation so I cant comment on how to place them in a blend shape sequence but Im sure its a case of keying them in at the start of a specific shape and the 'in betweens' will be figured out by maya. Dont forget you can pretty much animate everything in maya so Im sure it wont cause any probs. I think I did something similar with a uv texture as an over lay on my show reel last year.

as you say, just try it all out and see what works best for you

Cheers for now
Jay

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