displacement artifacts

[mic]

hello!

i have some problems with the displacement..

i have very bad (topology) model from zbrush. i wrote a simple noise displacement shader. and in motion i have some bugs - some areas flickers strangely - in one frame they appears, in another - disappears. not on the full model, only in some very little parts!

of course, space in shader is shader, normals are checked with faceforward (rsl).

binary dicing on, stitching on, many other attributes are tested - no result. sides 2..

here are some pics in attachment - part of the model, sorry for the quality.. in the red rectangle you can see the 'ghost' region.

(the object is static, camera is moving)

forgot: nevertheless the bad topology, without shader there is no flickering in the motion!

forgot2: the amplitude of noise is 0.4, dbound = 0.2, so the displacement is rather big..

// and the second question is..

is there any opportunity to transfer point attribute in shader?.. in displacement shader. in surface shader we can use 'useless' attributes like Cf, but maybe there is another method?

Edited November 27, 2008 by mic

[_suz_]

hi,

i can't see from u'r images what u'r problem is - u'll have to add zoomed in ones...

but an initial problem that i had with displacement is that the renderer puts bounding boxes around the poly's before it does the displacement shading,

so if u displace past the bounding box boundary, the poly's simply are clipped,

remedy:

add a properties OP,

click on the GEAR button and choose "edit rendering parameters"

> mantra 9.5 > shading > displacement bound

u'r displacement shader should have a "Km" the common variable that represents the max displacement

simply copy the parameter (r-click > copy parameter)

and place a reference copy in the properties> displacement bound field

...hope that does it...

[mic]

yes, of course, i wrote :

forgot2: the amplitude of noise is 0.4, dbound = 0.2, so the displacement is rather big..

=))

the problem hasn't yet solved, but i reconstructed the wrong topology in the flickering places and it looks much better.. nevertheless, i don't know the reason of this behavior, i can't post the larger images right now, so the topic can be closed..