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View Full Version : Stable Vector Displacement Node/Setup?



Chris S. (Fez)
07-07-2008, 08:26 AM
I would like to be able to reliably use .exr Vector displacement maps from Modo. The Dpont Vector Displacment node seems slow in addition to having trouble updating and displaying. It just seems generally a little wonky.

Are other folks finding the same? Is anyone using a "native" nodal tree that is more reliable?

dpont
07-07-2008, 08:32 AM
I would to know if you are using the last DP Kit update,
since there are some major improvements in the Vector Map node,
in term of speed and stability.

Denis.

dpont
07-07-2008, 08:49 AM
I just retrieved the last message about this,
I add the link here, because it includes also
the Modo's exr+geometry sample I used in my
tests.

http://www.newtek.com/forums/showpost.php?p=702743&postcount=9

Denis.

Chris S. (Fez)
07-07-2008, 08:56 AM
Denis, I believe I was using the latest but I can't be sure until later (I am presently away from the workstation). It will be a couple hours before I can confirm.

Thanks,
Chris

dpont
07-07-2008, 09:01 AM
Only if it has a preview image, older hasn't one,
stable it is, but Tangent space still need a geometry
scan, which I could not improve myself.

Denis.

Chris S. (Fez)
07-07-2008, 09:52 AM
Denis, I installed the Beta to do a quick test. The problem comes when switching the Display and Render subpatch level. The displacement goes crazy. Is this a bug? Or a limitation? Shouldn't we be able to change the Display and Render Subpatch level like in Modo?

dpont
07-07-2008, 11:09 AM
This kind of thing can't be changed in the node,
if display subD and render subD are different, the node
would need a new geometry scan, at new time it can
only ask to know if point count has changed,
then heavy things come from freeing memory
and redo the SubD or CC scan, this
has been optimized (for a third party plug).

Denis.

Chris S. (Fez)
07-07-2008, 02:01 PM
Ah. So it is a limitation, not a bug. My apologies. I didn't realize point count had anything to do with vector displacement. Indeed, the advantage of Modo's vector displacement is that the displacement can be applied to any subd level.

What would Newtek need to do to get Modo vector maps working in Lightwave with the same sort of flexibility as Modo?

Could they code a Vector Displacement "approximation" that uses the .exr to displace the surface in XYZ from the normals of the base mesh?

dpont
07-07-2008, 02:42 PM
Vector displacement is almost easy,
but Tangent space is related to the UV coordinates
and geometry coordinates, this is made in the node
for each (re-) subdivision with the SDK Mesh Edit,
so yes could be faster if it should be hard-coded in LW.

Denis.

Chris S. (Fez)
07-07-2008, 03:26 PM
Thanks Denis. I put in an inarticulate request for hardcoded displacements:

http://www.newtek.com/forums/showthread.php?p=718758#post718758

Chris S. (Fez)
07-07-2008, 05:14 PM
Denis, check this out: http://www.xsibase.com/forum/index.php?board=29;action=display;threadid=28834;s tart=0

"Basically the idea is to sculpt a high poly mesh in a sculpting program and export with as high a poly count as possible. Then in XSI RenderMap the surface positions of the base mesh and the sculpted mesh (to a float format image). Subtracting these two maps creates a vector displacement map where displacement is between points of the base and sculpted meshes which share the same UV values. As with normal maps, conversion to tangent space can be useful for deformations or to transfer to other objects."

Is it possible to set up a similar "Subtract" nodal tree in Lightwave using your Vector Displacement node?

* nevermind, now that I think about it your custom node is doing the same thing. Or is it? I'm confused.

dpont
07-08-2008, 01:02 AM
Of course, this is what it does,
substracting sclupted to original coordinates,
but to include negative displacement in colors,
there's also a shift and user rescale of vector.

Denis.