Problem with displacement maps saved from photoshop

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  02 February 2013
Problem with displacement maps saved from photoshop

Hi, I'm using maya and vray.
I exported exr displacement from zbrush.



If I use the displacement file from zbrush I get a correct render (on the right)
But if I open the file in photshop and saved the exr in any compression, I get issues with the displacement (on the left).

But I need to do some edits on the map in photoshop.
 
  02 February 2013
never had that issue before, but if you're using maya, have you tried setting the alpha offset negative half the value of the alpha gain? ie: alpha gain = 1, alpha offset = -0.5
 
  02 February 2013
Hi, I already setted that in vray, both images are using it.
 
  02 February 2013
As far as I know photoshop is (or at least was) not really good at handling exr and 32bit depth.
Are you color managing the file? Maybe you are adding some gamma correction to it while opening the file (while it should not be gamma corrected being both floating point and a 'data' image)
 
  02 February 2013
Use the tiffs that GoZ outputs. If you are using a renderfarm, make sure you copy them to a network directory so the farm can see it, because it defaults to your user dir.
Changing these value by saving to another format will break it.
 
  02 February 2013
the only problems that Photoshop has with EXR files is that it will open 16-bit EXR files as 32-bit and save them as 32-bit. That's not what you're seeing so I'm guessing it's something else like compression but I don't know if EXR does lossy compression at all.

But I never use 32-bit displacements with V-Ray. I always output 16-bit ones from ZBrush
 
  02 February 2013
Looks to me like you're seeing gamma or color mapping issues in your midtones.

Hate to say it, but Nuke's the only thing I trust to convert 16 and 32-bit maps between formats. Photoshop is absolutely terrible about leaving color space intact.

I recommend following the advice above and using the TIFFs exactly as output from ZBrush.

--T
 
  02 February 2013
hey Trey,

can you email me some details of that PS bug so I can follow up with them? I'm a beta tester for PS and they are good at squashing bugs.
 
  02 February 2013
As a work around the problem, I went with tiffs, that I can save from photoshop whithout problems.
I used exr for the compression, it gives 5- 12mb archives.
But I tested other softwares for saving compressed exrs, and it gave me the same problems.
I'm starting to think these compressed exrs, even through they say it's lossless, they do something with the image. I didn't try Nuke, cus I'm not familiar with it.
 
  02 February 2013
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