You had the following issues with the mesh that caused your problem.
-Model scale: The model was total height 4.8cm the lip area was 0.2cm with the bump around 0.02cm which may have lead to raytrace errors. Perhaps. Its good to work to scale.
-UVs: Did not give the right amount of space for each face most likely because the tools you used to layout the UVs were fooled by no evenly spaced edges in the mesh.
-Edge flow: Works against you when you subdivide. Huge faces on the forehead small ones on the nose. And you had star intersections in areas like the nostril corner which can cause issues. The goal is to try and have all the faces the same size/proportion within say 15%.(*you also need a lot more topology around the ears if you want to extract good maps from there. Build the ear completely in the lowRes )
-Exported the lowRes after sculpting and use that mesh to render with the 16bit displacement map I created.
Those are my suggestions. What I did was to scale your mode up by 10 and redo completely the UVs as well as delete un-needed polys under the model because they are not seen and take up UV space. I also added a few edge rings around the neck. Then I re-sculpted.
Results: No issues at all with the maps or render.
Thank you for the important information Dave.
I think these suggestions are very essential and believe that general topology recommendations and requirements for good displacement map extraction should be included and emphasized in the help pages. In fact for me this is more important than anything else I
Just to reiterate/ agree on what Ken and Dave said - the 7 point intersection’s a definite “No No.” In most production character geometry a 5 poly intersection is the max you want to have, and sparingly at that.
This isn’t a great example of topological flow, as it’s a starting generic basemesh that I’d use for modeling then retopologise for a final mesh. It could use more edgeloops around the eyes, the 5 point intersections on the brows are bad, as are the nose wing/ noslabial fold intersections to name a few problems.
I thought it might help the discussion on polygon distrubition. I focused on the nose/ forehead area, the distrubition over the rest of the head and neck is about the same.
I did not mean to scare you with the “15%” difference between polys. :) This is not a hard rule maybe its more like 15%-30+% for organic forms. And this is not just for Mudbox it is a must for proper production quality models for a great number of reasons for games or films. And for hard surface models forget about that 15-30 number. But you need to know what a triangle or a vertex that has more that five edges connected or any topology will do when you subdivide it and what that means for any texture you assign.
Perhaps I will post an example for you.
Or you can post a screenshot our your model and I can suggest yea or nea :)
I would also really appreciate if Xskorpion agrees to post different angles screenshots with wireframe on shaded of his original topology in Maya and the modified topology from Dave so that we can compare and learn.
Thank you in advance
i don’t have the mesh that Dave corrected, but he did mention how he solved it-
enlarging the model to 10 cm, twice it’s original size, and redoing the UV’s (i used the pelt tools before, wasn’t the best way to approach it in this situation) and adding a few more loops around the very low res areas.
seems like he didn’t change the star intersections, but was suggested to do so.
I was reading through the thread and thought you guys might be able to help me. I have a similiar problem to Xskorpion’s. I think my Uv layout is alright as i modeled the basemesh in maya and then exported it as an object into mudbox. I played around with the model and made the displacement map but when i checked if it worked in mudbox through the mesh displacement option i got wierd results.
I used the same settings off the “Rendering Displacement maps in Maya” thread. http://www.mudbox3d.com/forums/showthread.php?t=2241
My explanation is really bad so i made a picture. If anyone can help please post.
It’s hard to diagnose the problem without more info ie. a pic of the base cage and UV layout. Assuming there aren’t overlapping UV’s in the ears and eyes regions.. my first guess was that the vertex id’s on your mesh got re-ordered either from exporting from mudbox or from your export settings in maya so thier out of sync. Atleast thats what i’m use to the problem being when a mesh explodes.
My second guess would be that the base mesh has poles/stars in the ears and eye sockets from the way the stray polys seem to all be converging in those areas.