Donnie,

The problem has been there as long as I can remember even back into the Ray Dream days, and I think I did make a point of reporting the problem back in the c1 days. Most of the noise based shaders don't do their own bump map so the renderer has to pick spots around it, query the shader, and then figure out how the normal is changing based on those surrounding samples. I suspect that it must be hard or impossible to figure out where to take those samples for shaders based on global coordinates.

Here's where I get to say, "I'm glad you asked the original question". The new plug-in we just released, Velout has a solution. Included in Veloutis a tool called Filter. Amongst other things, Filter will calculate the bump for child shaders, including noise shaders set on Global coordinates ;). You can check out Veloutand download the demo from

http://www.digitalcarversguild.com/products/veloute/

If you have any other questions, please let me know.

Regards,
Eric Winemiller
Digital Carvers Guild
3D plug-ins for Carrara
http://digitalcarversguild.com

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins