LW to ZBrush - UV Problem

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  06 June 2006
LW to ZBrush - UV Problem

I know ZBrush does not like any overlapping UVs exported from LW, but I cannot find any way to stop this distortion on the seams when making a displacement in ZBrush from a LW UVMap. Whether the UV seam points are merged or not makes no difference.

I have used all of steve warner's tuts to the letter, which are very good except he uses ZBrush maps avoiding such issues. The maps are fine except for the edges.




The only thing I have noticed is that when I "Uv Check", the small window showing the UVMap is nice and clean showing no red or overlapping lines, but if I then click the edit icon the object (tool) in the main window does have a random red line. The UV Map as I said previously remains clean and creating a texture map removes the line.




I am at a loss. My LW Texture Map does not overlap except technically at the seams where they obviously share the same points.
Attached Images
File Type: jpg LWZB.jpg (39.3 KB, 81 views)
 
  06 June 2006
Let us see the uv map.
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Robert Wilson
UnCommon Grafx
 
  06 June 2006
I have attached more examples which will explain it better, but I think that with my particular LW-UV it will never work in Zbrush as none of the edges line up due to its complicated organic shape. The Zbrush Check UV looks fine, but the detail attached of the seam in Zbrush edit mode does not look right.. I could I suppose Post edit the Displacement Map in Photoshop, or simply use a ZBrush UV, but if there is a solution I would really like to know.
Attached Images
File Type: jpg LightwaveUVMap.jpg (79.7 KB, 33 views)
File Type: jpg ZbrushCheckUV.jpg (15.3 KB, 22 views)
File Type: jpg ZbrushSeam.jpg (35.4 KB, 31 views)
 
  06 June 2006
Fix seams resolves the seam issue in ZBrush edit mode (see Pic's). The problem is the Displacement Map still has the distortion at the edges.
Attached Images
File Type: jpg ZBseam.jpg (29.1 KB, 20 views)
File Type: jpg ZBseam2.jpg (22.6 KB, 18 views)
 
  06 June 2006
Try this:
In modeler, in the uv port with the mapping image in the background, massage the edges to fit inside the map. I've found that on occasion the map is right at the edges of the uv space and can cause this. Moving a few vertices can assist in saving hair, time and sanity.
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Robert Wilson
UnCommon Grafx
 
  06 June 2006
Yes, you are right even though in LW the Map is not overlapping or outside the box, in ZBrush it is.
With a 100% LW UVMap in ZBrush, the small Uv Check is good but in the perspective view there is a random red line.
If I reduce the Map in LW by 1% (therefore well within the box) there is no overlapping in ZBrush.
The problem is this makes no difference, the edges are still distorted.
See Attachements...



I can massage the edges back in LW and avoid the the distortion areas but it still does not explain why the seams are being distorted.
Attached Images
File Type: jpg EdgeDisplacementDistortion.jpg (39.3 KB, 15 views)
File Type: jpg ZBrushRedMark.jpg (25.8 KB, 17 views)
File Type: jpg ZBrushNoRed.jpg (20.9 KB, 9 views)
 
  06 June 2006
From what I'm seeing, your edges have quite a variety of information; it looks speckled. Those are driving displacement, as well, such that distortion at those points makes sense. To me, at least.
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Robert Wilson
UnCommon Grafx
 
  06 June 2006
Thanks uncommongrafx

I am not quite sure what you mean by " driving displacement". In the attachent below you can see a detail of the displacement edge. Yes it is varied but very contrasty and tonal in comparison the the rest of the map, making the model edges back in LW very bumpy.

Are you saying this is normal?
Attached Images
File Type: jpg Edge-Detail.jpg (14.5 KB, 20 views)
 
  06 June 2006
It has been for me.

For me it looks like ruffles. And if it looks ruffle-like to the eyes, LW will see it in a similar manner and give you ruffles.

When I say 'driving displacement' I'm saying that the contrasty bits are affecting your results by giving you an uneven edge, i.e., a ruffled edge.
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Robert Wilson
UnCommon Grafx
 
  06 June 2006
Yes I see.

So basically I need to deform very lightly, if at all near the edges.
Mind you its not that easy seeing where the edges are in ZBrush having spent the first few steps smoothing and removing them.
Will give it a go.

These are my edited steps in ZBrush in case I am missing a major step.

Import Object/Tool
UV>Txr
Uv>Check
Fix Seams
Store Morph
Dsmooth
SUV/SDivide (5 levels)
New Texture
Projection Mixer/Displacement/Normal Map
SDiv back to level 1
DPRes/SmoothUV/Adaptive/Create Displacement Map
Export
 
  06 June 2006
Going out on a limb here and presuming you have beta [9]: try a normal map.
It's been stated that they are cleaner than displacement maps. It may assist you in this regard.

I don't have Zbrush; using something else for displacements so I couldn't tell you if your steps are right or not. Check out the tute by Steve Werner as to how to export a zbrush map. It's the authority on the steps. IF you match his work, success is yours.

As for seams, if you place them where you know they are [torturous sentence], then painting in that area ought to be easier. For example, I see this is a tree trunk and roots; why not have the seams on the bottoms of the roots?

Thanks for the conversation.
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Robert Wilson
UnCommon Grafx
 
  06 June 2006
I have gone through all off Steve's tuts with a "fine tooth comb". They are great, but in part thats the problem, I am no Zbrush connoisseur (just started to use it to aid my LW flow), so I have relied heavily on his tut's and other people's posts. He unfortunately does not deal with this issue choosing to use ZBrush's own Texture Map.



Likewise Thanks for your conversation and input.
 
  06 June 2006
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