ZBrushCentral

Extract Thickness Limit and Thickness Retopology issues

ZBrush Usage Questions
#1

I’m really confused with the thickness limit with the extraction feature in the subtool pallet of ZB. Also when I try to retopologize an extracted skin. The new topology lines show through the model from the other side. This makes it rather difficult to retopo on this other side or to retrace the visiable low mesh original polyline flow.

When you do the extract feature on a poly model it adds new polys around the edges just before the thickness border. Instead of giving you a nice clean exacting extraction of the surface. It doesn’t matter what you do to the extraction surface and edge smoothness sliders and neither of them feature a “0” option

All I want it to do is preserve and repeat the original meshs wireflow on the surface for the new backface created with the new thickened extraction of that object- with a simple single poly wall border along the edges. Although a poly border slider to specify the number of poly stacks between the borders would be cool.

Last problem- Is there a way to sculpt on one side of the mesh like say the front part when it’s an extraction and not effect the backfaces side?

Sorry for the long rant. I’m having one heck of a time trying to walk around these issues to make an extraction thick enough off of an object and since the extraction feature adds extra polys to the surface- even when it’s a total non masked version extraction off of single faced poly object. Very frustrating. I’ve tried lots of things to solve it and nothing is working.

#2

Extract is not the best method to use for what you want because it always creates new topology. Try the Morph Difference Mesh method instead:

  1. Back up your model or use a clone.
  2. Go to the top subdivision level if you want to keep all the detail as the new mesh will have no levels.
  3. If you only want a selection of the mesh use Shift+Ctrl and the Lasso to select the portion you want.
  4. Press Tool>Morph Target>Store MT.
  5. (Optional) Snapshot the mesh to the canvas to help judge offset distance for next stage. Press Shift+S.
  6. Adjust the Tool>Deformation>Offset slider to move the mesh forward or backward by the amount of thickness you want.
  7. Press Tool>Morph Target>Create Difference Mesh.

A new tool called MorphDiff_meshName will be created in the Tool palette. Select this tool then:

  1. If necessary, flip the normals to get the new mesh to display correctly. Press Tool>Display Properties>Flip.
  2. To add edge loops along the edge, Ctrl+Shift+click on the edge to select the edge polygroup (press Shift+F to show polygroups) then press Tool>Geometry>Edge Loop.

Extract.jpg

  • For sculpting on front faces only, turn on BackfaceMask in Brush>Auto Masking.

HTH,

#3

Thanks for the tips and info Marcus. Is there a simple fix for this issue?

maskwonky.jpg

I made this model using extract at 0.35. Then I rigged and retoped it into a new model.

When I try to brush a mask on the backside of this model to hide it. The mask bleeds onto the front side. I tried turning on Backfacemask and that didn’t solve this problem. I need to do this because I am trying to project brush a crude david laserscan shape/texture model art onto the frontside. If I cant mask the back- it collapses to match the paper thin laserscan model.

#4

Backface Masking should work well for what you want. Which version of ZBrush are you using?

#5

I’m using Zbrush 3.5 revision 2. I have revision 3 on my destop, but it needs to be serviced.

I need to call pixologic tomorrow to get a new download link for 3.5 r3 for this laptop. I think I have it on my portable harddrive but I cant tell which one is right.

There’s an EXE like version of it and a RAR/ZIP openable version. The rar/zip openable one is revision 2.

I thought the EXE might be the release version of 3.5 before the revisions, but it might be R3.

Backface masking doesn’t seem to work on this model though. I don’t know why. Maybe revision 3 will solve that.

#6

You should upgrade to 3.5 R3.