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Liveclay/Voxel Paint workflow?


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#1 Gravin

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Posted 09 August 2012 - 10:34 PM

I was wondering if there was anyone here who could share there experiences using the liveclay and Voxel paint tools for sculpting complex characters and baking out to a low poly mesh. I've been playing with the possibility but my normal map results havent been all that great. I need to revisit my retopo mesh as there are some obvious issues there with self penetration.

The reason I approached the surface tools is because of the decimation tool. My character was getting way to heavy in voxel mode to even bake down (out of memory errors) but the decimation tools helped me cut the tri count to less then a third without loosing detail. I can get a bake down to ppp now but the normal maps appears to have some overlapping between the different parts and some general noisyness. Is anyone having any success using surface mode baking after using the liveclay and other related beta tools with complex multi part characters or I'm just doing something wrong here?

Edit: It might also be worth noteing that I do have some unnecessary cavities in my character that I plan to fill tonight. Could that be causing any issue with the normal baking process?

#2 Psmith

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Posted 09 August 2012 - 11:44 PM

This may not be the answer you are seeking, but, to me the simplest way to go about this entire process is to model in voxels, using "Res+" only when you run out of detail resolution - bringing the final voxel mesh into the 6 million triangle region of resolution.

I can go up to about 12,000,000 on my humble MacBook Air without too much delay and performance hit.

Use the AUTOPO routine without any density shading or guides - just to see what kind of mesh it gives you, at the resolution you want - add density and guides as needed - as shown in my video here (Part 5):

AUTOPO For The Rat

Merge the satisfactory result into the Paint Room for Per-Pixel painting to add the really high frequency details.

Export your model with the settings you require right from the Paint Room.


Greg Smith

#3 Gravin

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Posted 10 August 2012 - 12:09 AM

Thanks Greg,

For most things I would probably have gone about it the way you describe but there were some details that were easier to merge in models for but this required a good amount of resolution to keep crisp. There are a few things that I could recreate in the paint room but this would be kind of time consuming and I would like to avoid it if possible.

#4 carlosan

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Posted 10 August 2012 - 03:40 AM

This ?

Normal Map
What is a Normal Map?
http://wiki.polycount.com/NormalMap
--------------
Working with Cages

Cage has two meanings in the normal-mapping process: a low-poly base for subdivision surface modeling (usually called the basemesh), or a ray-casting mesh used for normal map baking. This section covers the ray-casting cage.
Most normal map baking tools allow you to use a distance-based raycast. A ray is sent outwards along each vertex normal, then at the distance you set a ray is cast back inwards. Where ever that ray intersects the high poly mesh, it will sample the normals from it.

http://wiki.polycoun...aycasting_1.jpg

Hard edges and a distance-based raycast (gray areas) cause ray misses (yellow) and ray overlaps (cyan).

----

http://wiki.polycoun...aycasting_2.jpg
The gray area shows that using all soft edges (or hard edges and a cage-based raycast) will avoid ray-casting errors from split normals.


Unfortunately with a distance-based raycast, split vertex normals will cause the bake to miss parts of the high-res mesh, causing errors and seams.
Some software allows you to use cage mesh option instead, which basically inflates a copy of the low-poly mesh, then raycasts inwards from each vertex. This ballooned-out mesh is the cage.

#5 Gravin

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Posted 10 August 2012 - 01:24 PM

Thanks Carlosa,

A little technical info always helps. I fixed the undercutting and self penetration issues in my retopo mesh and the baked maps are looking much much better but I'm still getting errors. The instanced parts of the character are a little weird but I imagine merging those into actual surfaces should fix that. There is this One major error that I don't understand...

highressurface.PNG normalerror.PNG

It might be hard to tell from the picks but it looks like the surface is completely missing and the normals are being baked off the surface below. It's the only surface that is doing this?

#6 Psmith

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Posted 10 August 2012 - 07:15 PM

Gravin:

It would be helpful to us if you could record a short video of the steps you are taking, so that we can analyze where the problems begin. You can use the free app "Jing" and the free server "Screencast" to do this.

Thanks,

Greg Smith

#7 Gravin

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Posted 10 August 2012 - 07:25 PM

Greg,

Will do, gonna have to wait though as I will have to find a way to work around the issue for now in order to meet a deadline. Thank you everyone for you help.




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