ZBrushCentral

Could really use some advice on UV's and D.Maps

ZBrush Usage Questions
#1

Hi everybody, I’m not a regular ZBrush user, so my apologies if I sound inept.

I’m working on a project that involves some simple geometric shapes with fine detail added in ZBrush. The job is under NDA, so I’d rather not post any images, but if necessary, perhaps I can illustrate my problems. Also, I’m the 3D animator on the job, so I’ve been using a ZBrush artist to do the sculpting, while I’ve been creating the base geometry and taking new OBJ’s and displacement maps back into Cinema 4D.

Here’s the problem I’ve been experiencing: The base objects were losing their sharp edges when subdivided in ZBrush. I tried a few different topologies, but was struggling to get a decent UV layout. So I suggested to the artist that we subdivide the models in ZBrush with smoothing disabled. I wasn’t aware at the time of the creasing options. This seemed to work very well. The ZBrush artist did some great sculpting to get the fine detail I was after.

The problem has come with my displacement maps, and I assume this has something to do with the UVs. If I look at the displacement maps, I’ve got thick white lines along the UV edges. These are particularly thick where I need the object to remain sharp. The effect of these lines in my renders is to bloat the edges which should stay sharp - exactly what I don’t want.

So now I’m wondering if I can rescue this, or at least fix the models but keep the details from the sculpt. For the record, the original meshes are around 1200 polys. The division required for the fine details has taken them up to around 8 million. I’ve been exporting OBJ’s in the 100K region and using the displacement maps to add the detail in Cinema 4D. I’d like to keep the UVs human readable, as I need to add some more texturing in C4D and I can only use one UV Map per mesh in good ol’ Vray.

If I’m missing anything that would help to get answers, please just shout. I’d be very grateful for some solid advice.

Best wishes,

K

#2

right now…from what I can gather…it seems like an error with the settings in C4D…but it could be the UVs as you’re thinking.

In order to really nail down the problem I’d have to see what it is you’re seeing.

If you can grab just a small chunk where the error is happening then we (the community) should be able to better help you with your problem.

#3

Or take another obj without NDA restriction to see:
1.-If you can duplicate the error and…
2.-If you can show it here and/or send to the comunity if we can reproduce the error:D

#4

A couple of things to look at:

  1. That the base mesh is restored before displacement maps are generated. Although if the mesh was not smoothed when subdividing in ZBrush this is still worth doing if you are using the original mesh in the render app.

  2. That Smooth UV is off when calculating displacement. As the mesh is not being smoothed the UVs shouldn’t be smoothed either.

#5

Thanks everyone. I really appreciate the response. I will try to put together a few images tomorrow.

@Marcus…I’ve been worried about how to restore the base mesh. The original mesh came from C4D via Go Z. So I’m bot sure how I would reload it. I’ve tried to export an obj from C4D and then load this at the base level, but this has exploded the mesh. As far ad I can tell the person who did the, very nice, sculpting didn’t store morph targets.

Thanks!

K

#6

The alternative is to export out the base mesh from ZBrush. You can press the Tool>Geometry>Cage button first if you wish. The important thing is that the low res mesh for which the displacement is generated is the same as the mesh to which the map will be applied for rendering.