I was wondering if anyone is doing decimation with CubicSurfaceExtractor? If you do use it, do you experience T-junction problems? (http://www.ldraw.org/Article526.html). So I get these single pixel holes in the mesh. Awhile back I implemented my own face merging using RLE and I tried to resolve t-junctions by putting up skirts. The problem was (I think) I was adding skirts to every triangle because I was lazy. That didn't turn out so well. Plus I was only merging on one dimensional stripes while CubicSurfaceExtractor merges entire quads.

Do you think by putting up skirts--ONLY AROUND THE MERGED QUADS--will resolve T-junctions?

Oh btw: I'm doing this to optimize my ram usage. But I found out the thing that eats up the most ram is the physics mesh. I actually resolved this earlier by using instancing of cubes, but that slowed my character controller (It uses convex sweeps) down to an unacceptable rate, like instead of having 200 characters at 30fps I can only do two characters at 30fps.

Interesting... I haven't seen this myself but I guess it can happen. I assume you are using the decimation built into the CubicSurfaceExtractor, rather than the MeshDecimator? Can you provide a screenshot of the problem?

Also, it seems these t-junction problems essentially arise through lack of precision. Are you seeing these problems in all parts of your map or only when far from the origin?