vraydispalcement on selected faces only?

[lukx]

Ok I have a problem with model from zbrush. I got two uv island for head and body to get better texture resolution. Same goes for displacement maps.
Now I bring model to 3dsamx and I can split model in two parts head and body but then when I don;t have welded vertices on neck I got visible seam.
But I need to use vraydisplacement for head and body and is there anyway I can have welded whole model in one and have two different displacements maps for head and body?
I tried putting two vraydisp modifiers with selected faces but it only calculates the one on the top. Is there any solution for this?

[joconnell]

Try using the vray multi sub texture and see if that behaves - put a vray colour map in the other slot with a 0.5 grey if you're using your zbrush displace map to push in and out at the same time. Other wise you'll have to paint a blend map between the two so one fades into the other and you get a better mix.

[lukx]

Thanks John I put multisubtex into vray disp mod but still getting seams

. Would be nice if someone form chaos gave some tips how to deal with it because based on this: http://www.zbrushcentral.com/showthread.php?t=150929 chaos rendered this model in vray and it was build of many separate objects and I don;t see any seams visible.

[joconnell]

I'd say it's a case of making sure that where the seams meet, they have the same grey values so the displacement amount is the exact same - might need to use the vray bitmap filter too?

[lukx]

it's totally strange because it got to do something with different uv islands. Because seams doesn't show if texture sits on one uv island but it only shows on connection of two different ones. I have no idea why would zbrush export disp for one object with different values. I tried playing with bitmapfilter but no change. How those people render those huge amounts of displacement details without using separate uv islands for different mesh parts. No way to do that is zb barley can export 8k maps. Hard to get answer form zb support also, I guess their busy doing siggraph

[lukx]

yep levels are totally different ! :
sent pixologic support message hope they can give solution how to export maps with same levels

[airstyle]

If you're using mutli map exporter in ZB then make sure you set the same scale for both maps. The default is auto I think, which would be why you have different levels on your maps. Worth a shot if you're still running into a brick wall.

[lukx]

when using vray multi sub texture do I need to use 3d disp? Because it seems that it doesn't work with 2d? When 2d on it seems I got same disp on all channels.

[lukx]

I exported 16 bit with same scale and now values are the same but still getting some crazy Frankenstein stitch : (

[vlado]

Does it get better if you use the VRayBmpFilter texture instead of the Bitmap one to load the bitmap file?

Other than that, making sure that displacement matches along a UV seam is a tough issue; we are working on a way to improve the situation for our next service pack. You'd still have to use a single mesh though - it won't work across meshes.

I think z-brush had a way to export the displacement per quad face - it might give you better results (but then again, it might not).

Best regards,
Vlado

[airstyle]

The manual method is to just clone and extend out the edges on the map itself if you can, it's a zb bug but I'm pretty sure there used to be a switch in ZB to prevent that happening to seams. It's disappeared from the latest multi map exporter though, it might be named / located something / somewhere else.

[lukx]

yeah I tried vRayBmpF but things get even worst:


I used 3d disp because I can't make 2d work with vray multi sub tex (or maybe I'm doing something wrong and 2d should also work)

[lukx]

I also tried 32 bit disp but man rendering this in vray takes years !