ZBrushCentral

High poly/details to low poly/texture game model

ZBrush Usage Questions
#1

Summary:
I’m trying to find an example of the complete workflow to sculpt and paint a high poly zbrush model, and get the low poly model with diffuse and normal maps into a game engine like Unity 3d. Using ONLY Zbrush.

Details:
I’ve purchased these books:
Zbrush sculpting for games, Introducing ZBrush 3rd and Introduction ZBrush 4, and ZBrush Studio Projects: Realistic game characters.
I’ve scoured youtube and google with countless searches, to find the complete workflow. Either I’ve missed some key point, or I’m just blind.

One of the BIG problems I keep running into is, everyone jumps to a different application to get the details onto the low poly model. I would prefer to use ZBrush for this, unless it’s just not possible.

I don’t have a problem with polypainting or sculpting.
I prefer to retopo manually, using ZBrush. I don’t have an issue with this.

But I can’t figure out how to get the high detail diffuse map and normal map onto my retopo’d, low poly mesh.

Example: Last night I decided to use a very basic object…a cube. I sculpted in a few details, and painted it various shades of brown. Fine, it’s a wooden block :slight_smile:

The, I retopo’d it. At this point…I’m just very confused about how to transfer the details, uv maps, etc over. I UV’d my high poly mesh at its lowest subdiv using UVMaster, and selected Copy UVs. I saved the polypaint to a 2048x2048 texture. Great so far.
Then, I pasted the UVs to my retopo’d, low poly mesh, and assigned it the same 2048x2048 texture. It’s unusable, distorted, etc. Black gaps everywhere.

Apologies for my frustration…but this seems like such a crucial workflow that I can’t find a solid tutorial on. Again, if ZBrush can’t really do this, I’ll have to use something else, though this would be very disappointed. But if anyone could point out the workflow steps, or where I missed it in a video or book, I would be very thankful.

#2

you can’t reuse UVs from one mesh to another unless they have the same vert count and order. You need to unwrap your lowpoly mesh and use project all to transfer all of your details from one mesh to another. In order to do this you need to subD your new LP mesh to support all of your highpoly details. Zbrush doesn’t like Lowpoly work as it usually has non uniform quads and or tris on the mesh which will cause problems in texture fidelity. This is the reason people use another software for baking most of the time. xNormal, Max, Maya, etc, basically anything that can do raytracing.

Remember that Zbrush is a SDS sculpting software first. It sounds like you’re trying to make Zbrush do things that it either A) isn’t made to do, or B) doesn’t do as proficiently as other software. When all you have is a hammer you tend to see a lot of nails…as they say…not sure who They are though.

Hope this helps fill in the gap for your workflow.

#3

Thanks, it does make sense. The whole project all and subdivide was where I was getting lost.
I downloaded topogun, but it was unable to handle a simple wooden post. Kept saying my geometry was invalid, but I couldn’t understand why.
So, I took the high poly wooden post, and put it on the lowest detail. I then used UVMaster to create the UVs.

I then retopod it and subdivided the retopo mesh quite a bit. I then used project all to get my texture and sculpted details on to the higih poly retopo. Lowered it back to lowest subdivision and created its UVs.

This gave…much better results. I was actually able to get something sorta decent into Unity, but there was some texture distortion (my high poly mesh had a lot of distorted triangles), but I’ll figure that out.

So…PROGRESS :slight_smile:

So…I guess I am still a little confused. It seems like the best thing to do is create a low poly game mesh (in blender, 3ds max, etc) and then subdivide details and paint THAT one. There would be no need to project at all, since you would only be working with the one mesh.