Polypaint to Low Poly

convolution223

Hello, I'm new to zbrush and I'm making my first character. I have a low-poly version of her made in 3d-Coat that I retopologized by hand and a high-poly, polypainted version from zbrush. As far as I know, what I should do now is UV unwrap the low-poly and then take them both into maya and set up the low-poly as a cage and then take them both into xNormal to get the normal map, but I'm wondering what to do about the polypaint. Will it transfer to the low-poly during the xnormal process? Or do I have to export it as a texture, but if that's the case, the UV's would be wildly different from the low-poly version (i haven't unwrapped the high-poly).

Essentially, I'm bent out of shape with anxiety over this whole process and I want to know I'm doing this right.

And one more thing, since it's a game character for Unreal, do I convert to tri's after all this or do I convert to tri's on both (high and low-poly) before taking them in to xnormal.

Thanks and sorry if I'm just overthinking this.

Lilacwine

You can bring your low-poly model into zbrush and use the project functions to project the polypaint from the high-res model onto the low-poly, which will keep the UVs.

You would have to subdivide your low-poly a lot so it can retain the polypaint data, then project from the hi-poly to the subdivided low-poly with UVs, you can then export the polypainted texture.

I'm not sure if this is the best way of doing this, I'm a bit of a novice but this has worked for me before when tinkering with stuff in zBrush.

BagelHero

You can bake a diffuse map just like you bake a normal map.

cryrid

Will it transfer to the low-poly during the xnormal process?

Yup. Xnormal has an option to bake polypaint along with the other maps. The highpoly obj object supports polypaint so it wont need UVs, just the low poly.

convolution223

Thanks! I've been really stressed about this.
Just that one other question then:
When do I convert to tri's? Do I do that before or after baking? And if it's before, do I do that to just the low poly or both of the models? Does it even effect anything if I do it before or after or are both viable options?

JohnnyRaptor

Triangulate just your lowpoly before baking, and make sure to maintain the same triangulation / edge angle afterwards

convolution223

JohnnyRaptor wrote: »

Triangulate just your lowpoly before baking, and make sure to maintain the same triangulation / edge angle afterwards

Alright, I'll do that. Thanks. I just did UV's. Triangulation won't destroy that will it? Well I'll find out in a minute...

AlphaMix

If you use Xnormal, Use "Bake Highpoly Vertex Colors", and in the High Definition Meshes menu, uncheck "ignore vertex colors", but only do that after you baked your AO map, for example, or else the polypaint will affect it.

Noors

Hello !
Would you know if Xnormal is still the best (only) way to bake huge meshes polypaint to a low poly texture ? Or if there's a way to do it in Zbrush now ? I'm messing with laser pointclouds so the polycount is quiet hardcore. Thanks !

Neox

marmoset and substance both are able to transfer vertcolors/polypaint to lowpolies

gnoop

Not sure about marmoset but Substance could only do it with something   around 10 -15 mil and not with GPU render.    30-40 mil model and both Substances just hangs.  Decimation in Zbrush doesn't work  basically  if you want to keep polypaint.    

  Xnormal could load 700 mil model (in my experience) taking forever just to read it.

Too bad after all the decades and gazillion useless features  Zbrush still doesn't have any easy means to bake things, neither  layers you could  really use, nor roughness channel  PBR style , nor  convenient procedural noise system , nor projective painting of any usefulness.    

Noors

Thanks, yes last time i've checked susbtance it wasnt great at holding heavy meshes.
I don't really care the time it takes as long as it reads it. I'll try to keep meshes under 100 millions tho. The issue in this project is that points color is my only source of color information, so the more points i mesh the better. I'll look into Meshlab aswell. Indeed a good baking tool inside zbrush would be most welcome.

Noors

Meshlab it is. In my case i can directly project the point cloud color to a low poly mesh texture, without having to generate a highpoly mesh.