Could you try your border testrender with mantra -r option ( no micropoly rendering ) ? I have seen several problems in mantra with mp rendering that are gone with raytracing only over the last few month. For example http://odforce.net/forum/index.php?showtopic=4246. [odforce.net]
It will not help The problem is much deeper. Function does not work how it is expected….i mean logically expected… because there is no words in the documentation about how it should work.
Nope, there is nothing “wrong” with it. I ran into this on Elektra. It's a bounding box problem. Basically, you're “displacing” the noise too far and trying to sample outside the bounding box of the metaball, which is always going to be undefined.
The way to fix this, apparently, is to displace the noise towards the centre of the metaball. However, I never got around to this. We just made the metaballs bigger with a smaller weighting and hoped for the best since we ran out of time… It was a big problem though.
If we're lucky “someone” will post the snippet of code that resolves this… if we're lucky )
Until a better solution comes along though, it's this or use i3D. Check out the 3rd party volumetrics solution mentioned elsewhere on the forum (bad brain, can't remember the name) which looked very cool.
