Linear Work Flow Texture Issues

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  06 June 2013
Linear Work Flow Texture Issues

Hello

I've been having some issues with my textures recently when using the LWF system in Maya (enable default colour; adjust image colour profiles, framebuffer etc.)

It would seem that my dark textures are been horribly crushed in Maya upon rendering, I assume it's something to do with the conversion within Maya but I'm unsure as to why. Could anyone help?

Ive applied a basic black and white texture to show the crushing.

Thank you,

James

 
  06 June 2013
with pure black and white there is no gamma correction. it only applies to in between values. maya's color management system only handles file textures, so any swatches you need to do manually. you can search jjj_gamma_tools, it'll help automate it.
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  06 June 2013
Also, there is no gamma correction on 100% saturated red, green and blue afaik.
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  06 June 2013
Thanks for the replies

Yeah it's with my texture nodes that the issue arises. It's almost as if the dark areas in the textures are pixelated and it's quality compressed right down within Maya.
 
  06 June 2013
Ahhh...ok i know what your problem is. You're tonemapping an 8 bit image. You need to change your file format to exr and set your framebuffer to at least 16 bit half. Problem will be solved.

The problem is not the file texutures, but the file format you are rendering to with your preview renders and tonemapping in the viewport.
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If animation is the illusion of life, then life is the illusion of reality.


"On ne sort pas DU REVE."

 
  06 June 2013
Thanks RedSand I already had my stuff set to OpenEXR and 32 bit float. It's a workflow I've used before I'm just completely baffled as to why its occurring now. Could my exposure node or any other settings be interfering with it? Would it help to post up my render settings?


EDIT: Yeah just took out my exposure node and that seems to have fixed it. The issue now is my image is very contrasted. :/ Has this ever been an issue? I'm using a look-up spherical for my lighting with a directional light.

Last edited by jameshodgart : 06 June 2013 at 09:15 PM.
 
  06 June 2013
When you removed the lens shader, were you sure to select the correct colorspace in your render view color management?
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  06 June 2013
Originally Posted by jameshodgart: Could my exposure node or any other settings be interfering with it?


Ah, ok. I assumed you were using the viewport tonemapping controls. I have noticed a number of times when using the viewport tonemapping controls that I've forgotten to set my file format to exr and framebuffer to at least 16 bit half, and then for the life of me can't figure out why i have noise and nastiness in my preview renders. lol. Thought that was happening to you as well.
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If animation is the illusion of life, then life is the illusion of reality.


"On ne sort pas DU REVE."

 
  06 June 2013
I have noticed textures getting clamped/stepped when using the built-in colour management feature. It happens to 8bit textures, but it shouldn't really. I think maya transforms the colorspaces in a destructive way. It doesn't happen with the old technique of correcting the gamma manually, so I stick to that.
 
  06 June 2013
Originally Posted by APerez: It doesn't happen with the old technique of correcting the gamma manually, so I stick to that.


Do you use jjj_gamma_tools? If not it'll speed that process up if that's how you prefer to work.
__________________
If animation is the illusion of life, then life is the illusion of reality.


"On ne sort pas DU REVE."

 
  06 June 2013
I'll look into those, thanks.

I also want to say that im stilll working with maya 2012, and i dont know whether the problem has been fixed in 2013.
 
  06 June 2013
Still useful for color swatches no matter what. There's a 'color swatches only' mode.

http://www.creativecrash.com/maya/d.../jjj_gammatools
__________________
If animation is the illusion of life, then life is the illusion of reality.


"On ne sort pas DU REVE."

 
  06 June 2013
You mean by manually adding the gamma node to the textures? I've did this with MR Sun and SKy but is there anything extra you need to do when working with IBL? In MR S&S you have to change the RGB values to 0.318?
 
  06 June 2013
Are you using Sun&Sky or IBL? They should both work fine anyway.

Which values are you talking about? Gamma is always set at 0.454 for a texture.

There are two things that you should care of when setting up a linear workflow. Making sure anything you bring into the renderer is in linear-space (thus converting textures and swatches to linear-space), and making sure you display your render in display-space (tone-mapped gamma 2.2). There are different options to display your render in display-space, you can use the Mental Ray tone-mapping (photographic lens shader with gamma 2.2) or an equivalent tone-mapping in a compositing software.

When lighting with an IBL, make sure the source image is in linear-space. It's easiest to stick with .hdr files, they're all in linear-space with a nice high dynamic range.
 
  06 June 2013
Just from the tutorials I've seen in the past the RGB values of Maya's sky node have been adjusted to compensate (I assume it's to gamma correct the sky?)

I think that's whats doing it to be honest, the gamma correction that comes with the exposure node then doubled with Maya's correction workflow. I've just removed the exposure node for now but would the gamma settings in the exposure node be set to 2.2 or 1?
 
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