I’ve been getting artifact/seams along the borders on my UV shell when I try to render my displacement in maya. I don’t know if its the mesh itself or the displacement map. I followed Scott Spencer’s displacement tutorial exactly too, and I’m getting really fustrated. Any ideas why? :qu:
First thing to do is check to make sure that no texture filtering is active. You don’t want texture antialiasing, mip-mapping, or anything like that.
I went to the displacement file node and I turned off the filter, which was on quadratic, re-rendered and got more details…however…still seams…
I noticed on my basemesh that I do have a few poles (5+ edges out of 1 vertex) and a couple tris. Would this maybe be causing the issue? I’m kinda of new to the whole 3d displacement thing so I don’t know if I’m allowed any tris or poles or w/e. If someone could tell me it would be much appreciated. I also noticed that the seams are at the edges the UV shells… that shouldn’t make a difference, should it?
(I don’t want any critiques of the displaced model, I just drew some bumps on it to see if I could get a smooth displacement btw 
)
Hi,
you are working with Maya 2008, right? I´ve experienced exactly the same problem. There are visible seams in the displacement showing at UV shell borders. The problem seems to be a change in the way Maya 2008 handles the Mental Ray Subdivision Approximation. I´ve imported the same low res mesh (as fbx) in Maya 8.5 PLE and did the same procedure for the displacement stuff (as taught in Scott Spencer´s Gnomonology video) as in Maya 2008. In 8.5 PLE the problem does not occur. So it´s definitely a Maya 2008 problem. I´ve spend the whole last night to find a workaround but no way… 
Marco
I had the same problem a few weeks ago. New model in 2008 was showing seams. A model done in 8.5 did not. The 8.5 model brought into 2008 showed seams.
Turning the filter to OFF in 2008 helped with the colour map(which was getting really screwed up and washed out). Leaving it to quadratic in 8.5 did not make the colour map screwy.
For the new 2008 model I had manually done the UVs (not automatic mapping) and the seams were pretty ugly.
I have read that you should have straight uv borders and nothing diagonally discontinuous.
I was able to remove most of the seams after adjusting the UV borders to be as straight or as true to the mesh as possible, or simply cutting the edges of the shell a row of faces behind the seam line, using the camera UV mapping option, sizing them to match the size of their neighbours’ faces, and separating the shell into more pieces. Spacing them out a bit. I dont know why but most of the seams disappeared.
In extreme close ups on some renders I can still see a few seam dots but I’ll live with it until someone can explain another way to remove them. I was not able to get the 8.5 model to be seamless when rendered in 2008.
I also had a bit of crashing–but discovered I had a couple of unwelded vertices and a bit of overlap.
I try to keep everything all quadrangles. 3 and 5 min max setting in the approx settings with .010
I didnt use the stored morph target to generate the model but the altered base mesh which I brought back into maya. Next time I will try it the other way to see if it makes any difference.
Thanks for the tips, but I guess I’m going to try to redo my model with just quads. I’ve also been noticing that the seams w/ displacement are much more appearent in Maya 2008 than maya 8.5. I’m hoping that autodesk comes out with a service pack to fix their buggy software in the near future. Perfectly straight UV borders, are u kidding me autodesk? pffft…
Try these settings:
Under Preferences --> Rendering:
Check ON –> Use Maya-style alpha detection on file textures
Mesh:
Normals ----> Soften Edge on your mesh(es), and Delete History
or Delete Non-deformer history if it is a bound or deformed mesh)
Check ON --> Feature Displacement in the Shape node of your mesh
SubDivision Approximation Editor only: Spatial and low setting: 3-5
Check OFF filtering in your file texture node.
I also got better Disp. maps from ZBrush using this DE Exporter quick code: DE-LCEK-EAEAEA-R32
which were then converted to .map file format for Mental Ray.
Hope this helps - sample attached 
Chris
I’m a bit curious about this matter:
Which is better, Spatial or Parametric in the Approx editor?
Or if one isn’t better than the other, what is the difference between the two?
I used the exact same settings–including converting to a Map file
and I still had the seams.
The same here. I tried everything possible but the seams are still there.
The strange thing is: It works perfectly in Maya 8.5 (PLE) and in Maya 2008 it doesn´t - so I´m sure Maya 2008 is the problem.
Marco
Well there has to be others doing displacements with 2008, but I tried googling it and the only posts that come up are mine!
I posted this problem in the Autodesk “Area”:
http://area.autodesk.com/index.php/forums/viewthread/2254/
There is at least one other person suffering from exactly the same problem.
Marco
EDIT: I´ve even emailed Scott Spencer a couple of days ago if he already tested his own workflow with Maya 2008 but I still haven´t got an answer (and to be honest - I don´t expect to get one - think he´s quite busy and gets tons of mails per day…)
EDITED AGAIN: I´ve just sent Scott Spencer a PM with this issue. Let´s see if he answers…
Hi marco…this other person would be me:D …Yeah, I also send him an email about the same issue, I’m sure he’ll come up with a solution.
And I got some respons in another forum saying that it could be a displacement exporter matter, turning smooth off, but it didn’t do the trick though.
Anyways, we look on and wait…
Hi,
yes, I also don´t think that this is a displacement exporter matter because the whole workflow as described by Scott Spencer runs perfectly with Maya versions before 2008.
Marco
I tried every option except sculpting the mesh with SUV turned on.
Another weirdness, I was having trouble with zmapped normal maps, but I made a simple tongue in 2008 and after exporting it back the zmapped normal map looked great(the UV shells were pretty simple though).
The displacement map came out with ugly seams–however, I rearranged it a bit and imported the new UV mesh back into zbrush then back out again and had greatly reduced the seams (again).
Hopefully you can get an answer. One change I note in 2008 is they have a separate displacement node in the subapprox editor above the polygon one. Maybe it has something to do with that.
One other thing: I find that if I leave filter type to quadratic in the colour map node I get a weird colour map seam and washed out colours. If I turn it off, the problem goes away. I dont have the same problem when I was using 8.5 with quadratic on.
Just to show you the problem with some examples:
The visible seams in Maya 2008:
A project with exactly the same settings/meshes/displacement maps in Maya 8.5 (PLE hence the watermarks):
my UVs:
Scott already answered my PM - he said he has yet to test it in Maya 2008 but his colleague has already done a lot of projects with his workflow in Maya 2008 without any problems… I have offered him to upload my original project files on my server. Maybe he can have a look on it…
Some of you might say: Just change the UVs etc… but the strange thing is that everything works fine in 8.5 with nothing changed!
Marco
I was going to PM you about SS and whether he replied.
I posted on Digital Tutors and asked the same question since I know they have 2008 --in fact they may have used it for one of their brush videos…, but didnt get a reply last i checked.
I know its maddening about the seams and the 8.5 lack there of, but the good news is I did manage to get 90 percent of the seams removed in a 2008 model, though the mesh was less faces than your sample.
Did you use roadkill to lay out the Uvs?
Hi,
no, I used headus UV layout (professional) for the UV layout (http://www.uvlayout.com). I´ve tried roadkill but headus UV layout is by far superior. (The above mesh is just a minimal test, a “nonsense” project just for the UV-seams-test - not a real project. In a real project I would try to place the UV borders where they are possbily not seen but that´s not always possible.)
Marco
Yeeeeaaahhhh! I have a solution!
I have just searched in the help system of Maya 2008 in “What´s new in Rendering”. I have found the following:
"Improved method for subdivision approximation node
Beginning Maya 2008, the subdivision approximation node produces ccmesh primitives instead of subdivision base mesh primitives. ccmesh primitives can define polygons with an arbitrary number of edges, rather than just triangles and quads. This new method can be up to several times faster than the previous. For best performance, use triangles and quads or a combination of both. "
So I thought the problem could be these (new?) ccmesh primitives that are now created (in contrast to subdivision base mesh primitives which were created in this case in older versions of Maya…)
I looked a bit further and found a way to actually change the new subdivision approximation node behaviour and to let the node use the old method - generating a subdivision base mesh primitive.
Just open the script editor and execute the following line:
addAttr -ln “miExportCCMesh” -at bool mentalraySubdivApprox1;
(mentalraySubdivApprox1 is the name of my mental ray subdivision approximation node - you have to change the line if your node has a different name) You can easily create a MEL button in your shelf for that…
That obviously changes the node behaviour to its old way and now my mesh looks beautiful without any seams:
(ccmesh: Nice “improvement” Autodesk! :td: )
I´m quite curious if this also works for all those who had problems with this, too.
Marco