Vray + maya + 32bit displacement maps

#1

Hello all

I have been trying to get my displacement maps to render out in V-ray for Maya properly but I cannot seem to get it to work.

I get parts of the model displacing properly and other parts do not.

The collar bone area, the bicep, shoulders etc. are not doing what they should be doing.

The displacement map is coming from Zbrush, and it is a 32 bit map and it is in .tiff format connected to a Vray material Shading groupss displacement slot.

I have the Vray displacement and subdivision controls added onto the model in the attribute editor.

edge length = 1.0
max subdivs = 16

2d displacement
displacement amount = 1
shift = 0

texture res = 4096
precision = 15

tight bounds checked on
filter blur = 0

#2

there should be something to get also the negative values to work…
in max its texmap…

Texmap min -10
Texmap max 10

the value depends on your dispmap range…

#3

I do not see a texmap min and max setting anywhere in the maya Vray settings.

I’ll check out the vray documentation though, thanks for the input.

edit****

I checked the documentation for Maya Vray and well I couldn’t find any settings for min and max displacement.

Hoping someone could shed some light on this issue for me.

#4

Hi Kpamir,

First off, don’t use 2D displacement… you should be using “Normal displacement” and adjust your gain and offset on the displace node. I also generally add my subdivision/displace attrs to the displace node/set/thing instead of on a shape by shape basis.

I’d recommend unchecking view dependent and setting the edge length to something like .010 as well.

In addition, there was a bug around the service pack VRay release that had pretty odd effects on TIFF-based 32 bit displacement (clamping at the water line, for instance). That’s been corrected in newer nightlies.

Hope this helps,

–T

#5

Hello Trey.

Would there be any way for me to convert my tiff displacement maps to say exr format?

I have attempted to use photoshop to do this but I cannot seem to turn off the colour management system photoshop has. The option to turn it off when the pop up window comes up is grayed out.

#6

I’d suggest using Nuke to do this if you have access. Photoshop will almost always screw up your displacement midpoint with a resave, and most commandline utilities (like Imagemagick) will convert to 16-bit.

–T

#7

Hi Trey

Ill give nuke a try at work.

You mentioned that you use a specific alpha gain and offset when rendering out displacements. I thought the whole point of using 32 bit images for displacement was so that you didn’t have to figure out the alpha gain and offset.

Also could clarify what you mean by this

“I also generally add my subdivision/displace attrs to the displace node/set/thing instead of on a shape by shape basis.”

Currently I have all of the Vray displacement and subdivision settings on the model, are you saying to use the global Vray settings?

Thanks again.

Khaled Pamir

#8

For negative displacement values to work go to attributes-vray-allow negative values. It is in your displacement map options.

And use .exr format. I have problems with 32 bit tiffs.

#9

Hello Muria,

Thanks for the reply, but I cannot find any options in the Maya Vray settings allow negative values.

Could you be more specific as to where it is?

#10

There are two places you can do it:

  • On a file node, Attributes->VRay->Allow negative colors

  • In the render globals on the VRay tab under misc ->Allow negative shader colors

Again, these may not be available in older builds.

In terms of adding displacement attrs, I generally don’t add them on a per-shape basis. I generally create a displacement set and attach it to an entire model or chunks of a model at a time (even if it doesn’t have a displacement attached), and add the displacement attrs to the displacement set. That’s mostly personal preference… it allows easier/faster tweaking of sub-d/displacement values, and keeps everything in one place instead of replicated hundreds of times on every shape in the scene.

To create a displacement set, select a model or group and Create->VRay->Apply single displacement node to selection.

–T

#11

I always thought Vray for maya never liked tiffs. especially 32 bit ones. Have you tried converting it to an EXR through photoshop? maybe it had trouble reading the map, however, if it had problems with the tiff format it would not have read it at all. So i could be completely wrong.

#12

Now, you can use a metaSL shader, in maya2011 (mentalray standalone 3.8) in only a few seconds to get pretty displacement results.
Look at this:

http://forum.mentalimages.com/showthread.php?t=7092

:buttrock:

#13

For “allow negative colors” go to:

http://img210.imageshack.us/img210/2862/vray.jpg

#14

There’s a bug with builds near to the time of the service pack release which clips TIFFs at the water line and also kinda mangles the displacement/sub-d attrs so they don’t work particularly intuitively (or consistently)… but that’s been fixed for months now if you have access to nightlies.

If you’re stuck using an old, broken build, I would suggest using EXRs as well as setting up your displacements Maya-style (on the shading group) and avoiding the use of the displacement control attrs altogether.

–T

#15

Hi Trey,

Could you outline how I would go about converting the tif displacement map into an exr?

I have never used Nuke, and after much fiddling around I finally figured out how to bring the tif into nuke (haha).

EDIT

Nevermind, figured it out.

#16

how can i temporarily turn off vray displacement? ive been trying to set the vrayDisplacenemtn node behaviour to “has no effect” and that doesnt seem to work. After ive set up my displacement properly how can i turn it off so i may go about testing other things in my shader?

#17

Its in render settings

#18

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