Physical Sun&Sky - Gamma correct scene?

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Old 03 March 2010   #1
Question Physical Sun&Sky - Gamma correct scene?

Greetings, todays questiona are:

1) How to Gamma correct an entire scene without adding gamma correct node to every shader!?

Maya 2010 -
C:\Program Files\Autodesk\Maya2010\GettingStarted\Assets
EmergencyCity.mb

Physical Sun&Sky
If Multiplier is set down to .4, it reduces the whites, but shaders still look unsaturated and flat, cannot read text on signs etc.
also I noticed in viewport harware shade mode, I can read the graphics on the building signs, but the render it's not readable.
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Old 03 March 2010   #2
The simplest is imo adding gamma correctors to the color nodes.

djx has a short list of things that gives you linear workflow in Maya. Not what you want but relevant to it.

If I recall correctly, you can just fix the gamma in the framebuffer setting in the render quality tab. Set it to .454 and that should work as a gamma corrector for all your textures. Right now I can't recall if you then had to fix the gamma correct in the lens-shader to get a good viewport render. all I can say then is that the lens-shader should be one of these three; 0.454(unlikely to be this one, things should balance out when it comes to gamma), 1, or 2.2.

Hope that guides you along the way.
 
Old 03 March 2010   #3
Thumbs up

thanks, good info!
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Old 03 March 2010   #4
you can use the framebuffer gamma setting to automatically correct all of your file textures, but this doesn't correct your color swatches. if you're working in linear gamma from the very beginning, this might not be a problem... just dial in your swatches to whatever looks good. if you didn't start linear, though, you'd have to gamma correct all of your swatches to 0.455 (1/2.2 = 0.4545...)

i have a script you're welcome to use that automatically inserts gammaCorrect nodes before any color-related texture in selected shading networks. here's the link: http://www.toadstorm.com/freebies/mel/hfAutoGamma.mel

the lens shader on your camera is what determines what you'll set your framebuffer gamma (or gamma correct nodes) to. a standard pc monitor is in gamma 2.2, so set the lens shader gamma to 2.2 and your framebuffer to 0.455. some people like the more film-like response that you get from gamma 1.8 (correcting to 0.555). whatever works.

when you render, remember that if you're using passes, they don't get gamma corrected. only your master buffer gets the lens shader. so you'd have to change the gamma of your image sequences to 2.2 in post.
 
Old 03 March 2010   #5
sadicus: Henry's script and a lens shader gamma may be your best option. If you use the frameBuffer gamma you will still have to remember to put the gamma back on any fileTextures that are not used for color (eg bump, reflectivity, diffuse weight, glossiness and so on). So you are not really simplifying anything by using the frameBuffer gamma.

-- David
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Old 03 March 2010   #6
Simplifying work is only reason for setting Frame Buffer Gamma=1 ?

I have permanent confusion with LinWokflow, and last time i was satisfied with my setup. But leaving Frame Buffer Gamma at 1 addle me again...

My last achievement in LinWokflow:
I use Fusion for compose, so setup involve fusion (and photoshop also) manipulation. But as for maya
-Frame Buffer Gamma = 0.45
-Frame Buffer Data Type- 8bit
Setup lighting and shaders. Switch Frame Buffer Data Type to32 bit, render, compose. As for shaders- i paint only color, but map different attributes (diffuse, reflectivity, etc) through the ramp from color. So i change ramp colors on basis of render wiew, by sight, so i do not confuset with correcting any walues at this stage.
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Last edited by kiryha : 03 March 2010 at 09:32 AM.
 
Old 03 March 2010   #7
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