Vector Displacement help

[Lehm_2001]

Just started messing with vector displacement. At the moment just using procedural noise maps. what I'm trying to figure out is how to go negative in a certain direction. For example if I have a red spot it will displace right in the x axis. What color does it need to be to point the other direction? As far as I know there's no way to make it negative red. The values seem to be mapped so that 0=0. Rather than 0=-1, which is the way I thought it was supposed to be.

Hopefully this made sense.

Jeff

[vlado]

The red and green channels are 0.5-centered, e.g. 0.5 (medium grey) is "no displacement", 0 (black) is negative and 1 (white) is positive.

Best regards,
Vlado

[Lehm_2001]

I finally realized what my mistake was. I was using black as 0 displacement. When its supposed to be Grey.

Also ran into something else. Is displacement not multithreaded? I was rendering some grass. And the cpu using would often drop to 12%. So it only appeared to be using 1 of my 8 cores.

[vlado]

Raytracing of the displacement is multithreaded, but the generation of the displaced geometry is not.

It might help to increase the Dynamic memory limit parameter in the System tab - it will give V-Ray a chance to keep the generated geometry longer instead of re-generating it.

Best regards,
Vlado

[Lehm_2001]

Thanks vlado! Upping the dynamic from 400 to 2000 decreased render time by 60%. Out of curiosity is there a reason the generations cannot be multithreaded?

And lastly the fruits. Not perfect but I think it will suit my needs.