Major updates to this guy.
I was having issues with the displacement around the eyes and the mouth. There were problem tiny polygons in these areas that were going crazy on certain morphs. The real problem was finding which morph caused them, as I have about 8 maps there that are animating ina and out with different morphs.
My first problem was that the base mesh for this guy was created in 2006. zBrush didnt have UV unwrapping at that time and I had used AUVTiles. I had no idea which tiny square contained the eye and mouth areas that were a problem. To get an idea, I painted out the polypaint and replaced all colour with white. I then painted the edges of the eye and mouth red. Saved out a texture and brought it into photoshop. It turns out I dodnt really need to, as the areas that were off were pure black dots in otherwise gray areas. I could spot them a mile off.
The one thing I did realise doing this however was that on really thin areas (around the mouth and eyes) in zBrush if you paint inside the mouth, the red was leaking through to the outside of the cheeks. I experimented with this a little, as I thought it might be affecting the displacement. I painted these areas out using inflate. It did help, and I would recommend you check for it. Its an issue I think on zBrush’s part, but honestly it’s not hard to fix. (TIP #1)
I worked with this for a while until I re-looked at my old DonQuixote mesh (see last post). I needed to fix a small geo problem which meant a topology change. I brought the new mesh into zBrush and re-projected it. What I saw when I hid the main part of the head was inside the lips was thousands of tiny ‘shattered’ polys just waiting to ruin any animation I did. After an hour’s worth or poking around I realised these didn’t appear if I projected first at level 1, then divided the new mesh, took the original up to level 2, re-project, divide new mesh, level 3 re-project.
TIP #2 For projecting old displacements onto new meshes DO IT PER SUBDIVISION LEVEL NOT DIVIDE DIVIDE DIVIDE PROJECT
I think the above is the root cause of exploda-polys for animated displacements.
If you DO have exploda-polys in a complex displacement node tree you can try TIP #3. Create a R;128, G:128, B:128 gray texture the same size as your displacements. Call it NullDisplacement. This is going to do have no effect whatsoever on your mesh. Then its a matter of upping the display subdivision level in openGL so you can see the problem areas in openGL, then replacing your displacements one by one for Nulldisplacement. This will tell you which map(s) are causing the problems. If you open this in photoshop it’s an easy matter of cloneStamping the offending areas out.
All in all its half an hours work if you know where to look. I am thinking of doing a tutorial on “Debugging Displacements” If anyone is interetsed, let me know.