displacement artifacts

["kim aldis" <kim(at)cg-soup.com>]

I'm using displacement maps in a way that requires a degree of accuracy. I'm making small, slightly raised lumps using a matte image to drive transparency. For the displacement I'm using a slightly shrunk and softened - few pixels - version of the transparency map. This gives me a nice rounded edge to the raised, circular lumps. As you might guess, though, I'm getting some artifacts. Unusual ones, though. Slight pixelation around some of the rounded edges and little black marks on the inner areas; where you wouldn't expect them. upping the length doesn't help but increasing the subdee on the mesh - stupidly increasing - does. I'd rather not do this because it's hitting the render times.

 

has anyone seen this; any thoughts?

 

cheers.

 

 

 

kim(at)aldis.org.uk