MAX+MUDBOX retopo question

jimmypopali

I'm sure this can be easily answered but I'm kind of new into the sculpting for low poly world.

I use Max and Mudbox in my workflow. Now I have been able to get the low poly out of Max into Mudbox, sculpt the detail, grab the normal and re-apply it on the low poly into Max.

Now the thing I need to get straight is that when I need to go and rework the low poly (say I don't even start off with the low poly - just take the high poly straight into max to make the low poly).

Now I have a normal map from Mudbox, and a re-worked low poly model in max, how to the UV's line up? The Mudbox will have different UV layout to the re-worked low poly. Now I have a low poly model which the normal map won't line up on.

Now this is a guess, but I'm assuming I could take the low poly back into Mudbox and apply THOSE UV coordinates to the high poly to get a more acurate normal bake.

I'm trying to get my head around what people do which is easiest (and possibly easiest to explain)

tldr; new low poly UV's wont match with sculpted normal bake - what do?

Thanks guys.

sl0throp

IN Maya it's called transfer maps...can you do this native in Max or do you need polyboost, not 100% sure.

pior

Dont try to transfer, just rebake. Transfer would only work with Object Space normalmaps. Since you are more than likely using Tangent Space, you have to rebake, theres no trick around that. (TS depends on tangents, and they change as soon as you edit your lowpoly.)

jimmypopali

So you are saying to take the road to import the high and low poly back into max and bake through MAX?

I think through some tests last night, the normal map didn't really read well onto the low poly geo as well as I thought. Maybe baking in max can get a better result?

oglu

if your mesh needs some hard edges you have to use max or xnormal annyways...
cause mud dont support hard edges for baking...

in the SAP version, mudbox supports transfer details and texture baking from one to an other mesh...
with differen topo, different uvs and preseves sculpt and paint layer...

sl0throp

Maya transfers Tangent space normals just fine, Xnormal is good as well. Same difference.



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pior

I wouldn't do it that way. If you need to transfer a TS normal map from one lowpoly to another, the only way would be to convert the map to Object Space, transfer that, then convert to TS.

If you simply transfer the TS using regular projection/transfer algorythms made for diffuse transfer, it simply wont work. Now there might be some cases when it might look semi-correct, but then its a matter of quality expectations. If you're fine with a final model with weird warping and shading artefacts, then go for it. But if you need accuracy, you need to take in consideration the following :

- a rotation of the UVs will make the RGB values of the normalmap useless;
- every added edge contributing to a refined shape will modify your tangents and create artefacts.

Now, there is a tool/shader written by someone here on PC, doing TS transfer. I remember it was tested successfully on a DW model, a fat demon with a mace if I remember correctly. Maybe someone has a link to that ?