Maya and ZBrush displacement maps

# 1 15-10-2007 , 03:25 PM

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I've been making a simple displacement map in ZBrush for a model I started in maya, but when I port it over, the object looks rather "fat" I've taken the alpha multiplier into account (multiply/divide note from the file to the displacement map), but I think my problem stems from the alpha map base colour being 50% grey. doesn't maya do displacement from black? This would explain why everything is getting displaced, even the stuff that shouldn't be.

can I adjust the maya displacement map so that it works from 50% grey rather than black (so I can have some negative displacement too?) or have I got to somehow get the base colour for the displacement map from zbrush to be black?

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# 2 15-10-2007 , 03:40 PM

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Hi there edward, yes you have to do that with it, off the top of my head its the alpha gain that you have to set to -0.5, rarther than go into a legnthy explanation of the settings and stuff theres quite a few videos on you tube about rendering displacment maps, best off doing a search for them.

Oh and on Pixologics site theres also tutorials there too using the Displacment exproter and then setting in maya etc etc

Hope it helps

"No pressure, no diamonds" Thomas Carlyle

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# 3 15-10-2007 , 03:48 PM

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Steve ya bugger ya beat me too it. LOL

Edward: this is the easiest and effective way to do it.

the other settings would be to make sure that make sure feature displacement for the mesh is OFF in the Attribute Editor, make sure you have a subdivison approximation node for the mesh, then in the AE for it make sure the subdivision surface quality is set to spatial and the settings for the min is 3.

that should cover it.....

happy rendering............

Jay

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# 4 15-10-2007 , 03:52 PM

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Hi! First of all what kind of dispalcement map do you have? It's made with zbrush displacement native maps, or is done with the alpha displacement exporter? I made displ maps using the ADE. Why? Well zbrush displacement maps have no scale imbeded so to speak.that means that you back in maya have to find for yourself an alpha value that is apropiate.With ADE you know that the alpha value should be 2.2 in maya, if you checked the adaptive option in ADE (i don't have time to explain all of that).To balance the 50% gray, you have to set your alpha offset to -50% of your alpha gain value, through an expression : for ex. file1.alphaOffset = -(file1.alphaGain/2);.So just right click on your alpha offset field and choose expressions and write like above.Wish you luck.If you have 10$ you can get from gnomonology website a wonderfull tut by scott spencer.(if you have luck with an torrent account.....) user added image

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# 5 15-10-2007 , 10:44 PM

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Thanks for the help. Just for anyone else looking at this, it's alpha offset that needs adjusting, not alpha gain (the latter is a multiplicative factor)

The map I have is just a basic one made using the displacement thing in the tools menu... I'm new to zbrush, so I can't say more than that.

anyway, here's the result of my work user added image

the treetrunk was formerly very smooth, but now has nice displacement lumps and detail. The leaves still need work, I have some odd corners that shouldn't be there if anyone has any iedea where they come from?

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# 6 15-10-2007 , 10:58 PM

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Hehe it was a guess off the top of my head.

It might be the edges of the map, Z allows you to extend the border if you use the multi displacement exporter

"No pressure, no diamonds" Thomas Carlyle

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# 7 15-10-2007 , 11:08 PM

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no no, those corners are from maya. They are just polygon spheres that I stretched. I have smoothed the normals, but to no avail. Maybe it will be a bit less obvious when I texture the leaves.

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# 8 15-10-2007 , 11:31 PM

Maniacal boy king of Babylon
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Here's a link to a very useful videotutorial on the displacement maps from z brush to maya;

https://www.edwin3design.com/root/news.htm

good luck

nice tree btw user added image

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# 9 17-10-2007 , 10:56 AM

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hi! I forgot to mention that you have to use a surface aproximation, usualy for zbr meshes -> subdiv aprox of type - parametric and try from 2-3 to whatever is apropiate for you depending on you hardware and the maps LOD. Good luck!

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# 10 18-10-2007 , 08:50 AM

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thanks for all the help you've given, it's looking quite nice now. I mentioned an odd problem in another thread (I meant to put it in here) but I'm using mental ray now (as I had intended all along ultimately) and that clears the messy shapes up, no idea why.

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Maya and ZBrush displacement maps

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