VrayDisplacement problem

[simmsimaging]

I'm playing with Zbrush 3.5 and having an odd problem. I exported some test geometry and a displacement map, and the displacement seems to work fine with the Displace modifier, but doesn't seem to work at all with the VrayDisplacement modifier. I've exported it a couple of times now and tried everything I can think of.

Is there a reason why it would work with the Max one (albeit crudely due to the geometry density) and not with the VrayDisplacement modifier?

Thanks /b

[jacksc02]

Brett,
Give the Vraybmpfilter map a try

http://www.spot3d.com/vray/help/150S...ter_params.htm

[simmsimaging]

Thanks - I did try that but it makes no difference.

It's an odd problem. I made a simple 'meatball' in Zbrush and exported geometry and displacement, and loaded that in Max. For that both the Max displacement and the VrayDisplacement modifiers worked fine, and the same displacement amount in both modifiers gave the same result.


With the test geometry (a liquid sculpt it's just not working. I cranked the displacement amount up 10X or more for the VrayDisplacement and it's now starting to displace, but the mesh is falling apart and it looks super rough, even with tiny displacement edge lengths.

If anyone has a moment to check it out and see what I'm doing wrong I would appreciate it. Link to the mesh and map is below. The two displacement modifers are on the mesh now, just turn on the Turbosmooth and Displace for Max version, and turn those off and the VrayDisplacement modifier on to try the Vray version.

Any help is appreciated

Filename:Splash_Disp_problem.zip Filesize:2.4 Mb Download Link:http://www.simmsimaging.com/xfile/l3iznfg2brh3

b

[stevesideas]

Is it anything to do with the units or scale of the object you are importing ? Could it have negative scale values ? Just guesses really !

[simmsimaging]

I don't really know but good thought. Thanks

The object was scaled up after importing. However, it's the same object being hit with both modifiers so there is still something odd in there. I'll try it later with a non-scaled object to see whether it matters.

b

[simmsimaging]

A quick test showed that bringing the scale back to 100% made the values of the two displace modifiers line up more, but it's still not working properly in that the mesh is really blocky and messed up looking, even with really low edge length values.

I've tried view dependent and not with the same result.

Other meshes work fine for me, not sure what is different in this case.

b

[stevesideas]

Normally if I have any scale issues I just create a max object: sphere or something, set the sphere to the pivot point of your object, collapse the sphere to a mesh or poly and then attach the offending object....and then of course re-apply the mapping/vraydisplacement mods.

[stevesideas]

Strange. Have you turned the bitmap filter off or right down to 0.01. I know you have to do that when you use zbrush maps for displacement. Is the map 16bit ? I think they can be blocky if they are 8 bit and maybe the max displacement is just handing it better ? not sure other than sorry.

[3DMK]

When ever I have weird issues in like this & others it is often fixed with a 'Reset X-Form' modifier & collapsed to mesh/poly.
It seems certain things in max work off the original model size, and not to what you have scaled it to.

[vlado]

It seems that your displacement settings were too low, which caused the cracks; switching to view-dependent displacement with edge length about 4 or 2 worked much better.

Switching to subdivision displacement also worked much better than regular displacement, since zbrush calculates the displacements relative to a smoothed surface, and not the low-poly version.

Finally, per-face displacement mapping does not work well with V-Ray, as V-Ray needs to sample a little outside of each face in order to calculate the displaced normals properly.

Best regards,
Vlado

[simmsimaging]

Thanks Vlado. I have never used the subdivision mode before.

b