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Question? Transfering Polypain or Polygroup information between subtools.

ZBrush Usage Questions
#1

Hello,

I have a textured high resolution model with UV’s and polygroups. I need to create a lowpoly, by decimating it and then generate normals and textures using xNormal outside. I can’t use “Keep UV’s” in “Decimation master”, as it results in bad topology.After decimating the model, I loose UV’s and polygroups. Is there a way to transfer polygroups information from one subtool to another? Or maybe somehow try preserve it during decimation process? Both subtools are exactly in the same place, the the only difference, one is highres and another is lowpoly.
As far as my knowledge of Zbrush goes, the only way there is in zbrush is to project polypaint information, but its buggy as hell and won’t recreate the polygroups from those colors. Assigning polygroups by hand is time consuming and doesn’t make any sense knowing I just had that information one step before.

Maybe it can be done using custom scripts? If yes I will be happy to pay for such an amazing tool.

Thank you!

Attachments

Lowpoly_UV.jpg

#2

Why not use ZRemesher and stay in Zbrush?

#3

You can transfer polypaint to another subtool by using Project All. The subtools need to be close in shape. They also need to have a similar polygon density, otherwise you will lose polypaint definition.

A basic workflow would be:

  1. Duplicate your existing model.
  2. Decimate the copy to reduce the load for ZRemesher. ZRemesher will give you a good base mesh topology.
  3. Subdivide this new mesh until it has about the same polygon density as the opriginal.
  4. Project the polypaint and high resolution detail from the original mesh.

You could then assign new UVs to the lowest level and convert the polypaint to a texture map.

#4

Thank you Marcus for the reply, its just not the thing I need.

My high resolution mesh is all that you described. Great topology, UV’s, textures and polygoups. Making another one just like it doesn’t make any sense.

I need that mesh to be decimated triangular mesh, to exact polycount I need, with high precision to the high resolution mesh. And Decimation master does pretty cool job. All I need is my pygroups from the original mesh. If only there was an option in Decimation master to preserve polygroups. Then can have rough edges, I don’t care. Is why I really need someone with zbrush scripting skills to come up with an idea on how to implement this. And I’m ready to pay for that.

#5

When I said duplicate your model I meant press Tool>SubTool>Duplicate, not create a new model from scratch. All the functionality you need is already in ZBrush, you don’t need a special zscript.

You can preserve polypaint with Decimation Master by using the options in the Preferences>Decimation Master sub-palette. So, before using Decimation Master:

  1. Press Tool>Polypaint>Polypaint from Polygroup.
  2. Turn on Preferences>Decimation Master>Use and keep Polypaint. (You may need to experiment with the Preferences>Decimation Master>Polypaint Weight slider.)
  3. Decimate youir model.
  4. Press Tool>Polygroups>From Polypaint. You may need to experiment with the Tool>Polygroups>P Tolerance slider. I got good results with a value of 0.5.
#6

Hey Marcus,

See I’ve tried it all now. And its not what I need it to do. Keep polypaint does exactly the same nonsense as Keep UV’s (Decimation Master), it modifies the mesh, marks the UV border on the mesh, and results in pour topology on the decimated mesh. Lots of little triangles on those borders, and it results in lots of artifacts in the realtime engine.

But I do understand that its easy to think that those tools in zbrush is all I need. But they don’t work for me. Also recreating polygroups from polypaint after projecting, well that thing doesn’t work, it produces just crazy results, lots of polygons have their own polygroups assigned, and on uv it looks like a mess. No matter what tolerance you use. It just doesn’t work as should.

I’m pretty aware about the current tools in zbrush, they don’t work. In this image you can see the middle model, decimated and split to polygroups by hand, this is what I need to be done automatically after decimation. I don’t care about the precision of the borders, I jsut need them to somewhere around that area where they were. Hope that will clarify what I need.

Decimation_polygroups.jpg

#7

You could try GoB to Blender. Maybe you could get what you need from there?

#8

In an earlier post you said rough edges to the polygroups were OK, so I assumed that the polygroups didn’t need to be precise. You won’t get straight lines to your polygroups as Decimation Master doesn’t take account of them.

You would need to use this workflow:

For a single subtool:

  1. Use Groups Split to split the subtool into several subtools based on the polygroups.
  2. Turn on the Decimation Master>Freeze borders option. This will leave unchanged the vertices at the mesh [polygroup] borders.
  3. Pre-process All and then Decimate all the subtools.
  4. Press Tool>SubTool>Merge Visible (make sure the Weld option is on). This will create a new tool in the Tool palette.
#9

I need that mesh to be decimated triangular mesh, to exact polycount I need, with high precision to the high resolution mesh.

Why?