PDA

View Full Version : Strong displacement flickering on camera move?

visartz
04-28-2009, 05:41 PM
Hi,
i'm hardly tryin to model and shade a fir tree, like the trees in the movie "open season"..

After i got the bark shader working, there is now the problem of the fir needles.
As you can see on the image below, the "leaves" of the trees look like starburst effects of a "lens flare" shader oder like a sphere with several displaced (?) rays.

That was the way i tried to do it..
I simply wrote a shader, that displaces a lot of rays from the sphere..
The problem is, that the shader looks different in every frame, if the camera moves in any way, it is flickering..

So do you think i chose the right approach and if yes, why is the shader flickering?

Thanks
Chris
divanovic
04-28-2009, 06:45 PM
Hi there,
which software are you using?

if it is maya, I got few ideas what could be the problem, if not...

cheers
Dejan
visartz
04-29-2009, 09:41 AM
hey,
thanks for your answer..
sorry, that i forgot these important details..

i'm using maya 8.5 with pixars renderman studio..

thanks
divanovic
04-29-2009, 09:54 AM
hey there,
if the leaves are moving and the texture seems to float, I guess that it is a placement problem, meaning that displacement texture is using 3D placement, or world space.
Since it is a custom shader, you would probably now if that is the case.
One workaround may be to make a 'texture reference' under 'lighting/shading > create texture reference object'. That way, Maya 'locks' the texture on all objects selected.

If the leaves are static and only the cam is moving, well, sometimes if the displacement map has dense noise, that can happen. Better AA should fix the problem, or blurring a texture a bit.

One more thing, if you haven't done so already, try assigning a different but similar tex, maybe some inbuilt procedural...

just some ideas,hope it is useful
cheers
Dejan
CGTalk Moderation
04-29-2009, 09:54 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.