linear workflow in V-ray for Maya - still confused!

[Richard7666]

I have read so many different ways of doing this recently my head wants to explode. Also, for my diffuse texture file nodes, do I want to only add the Vray Input Gamma attribute to diffuse textures? Not even say, coloured reflection textures? What about greyscale textures?
I've attached a screenshot of my settings and the results I get with them (note the splotchy roof is because it's a blend texture)

I have added a Gamma node to the diffuse colour slot for the roof material, as you can see the colour of the Gamma node (colour palette window on the right) matches the rendered result. However, the viewport and the material's diffuse colour slot swatch show as a dark brown!
The same thing happens with the wood texture I have shown in the hypershade; the material swatch can be seen to be very dark compared to the actual texture plugged into its diffuse slot.
Note that the 'affect swatches' option in the Color Mapping section of the render settings has no effect on swatches unless I set the gamma in there to 2.2. However, doing that causes double gamma to be applied (as I already have the Vray Input Gamma nodes on textures and Gamma nodes on swatches) and the render becomes washed out.

If someone can tell me what's right and what's wrong in my setup, I'd appreciate that. *Note that I save as 16bit EXR and do a bit of post work in Photoshop but not much beyond a bit of levels correction. I'm not bringing the images into Nuke or anything fancy.

[bazuka]

amigo hehe its simple

on color tex apply texture input gamma,

linear mapping 1/1/2.2

and turn on sRBG inside VFB

let me know does that works for u

p.s. or u can send me a piece of scene on PM, i could make a setup for

[Reaversword]

Besides, if you use file textures, remember to activate vray extra attribute "Texture input gamma" (in the maya file node) attribute editor, Attributes>Vray>TextureInputGamma. If you're working at gamma 2.2, then leave it at 2.2

[Richard7666]

So apply the Texture Input Gamma attribute to ALL coloured textures, eg the reflection texture of the copper roof? Okay.
Did you mean to tell me to also tick "Don't affect colors (adaptation only)" though Bazuka? Because hitting the sRGB button in the VFB makes every really washed out without using that option. It's still washed out even without it though.




Something else must be wrong here surely?

EDIT:

this post http://www.chaosgroup.com/forums/vbu...234#post557234 implies that no, I don't want to apply the 2.2 attribute to reflections.
but this post http://www.chaosgroup.com/forums/vbu...719#post542719 implies that I DO need to gamma correct reflection textures!

Ugh!

EDIT2:

this is more like it?

[CAPTURE_MM]

Our linear workflow involves the following:

Render Settings -> Vray Common
-> "Convert image to sRGB for RenderView" CHECKED

Render Settings -> Vray
Dark Mulitplier : 1
Bright Multiplier: 1
Gamma : 2.2

Affect Background -> CHECKED
Subpixel Mapping -> off by default, but check if needed
Don´t affect Colors -> CHECKED
Linear Workflow -> NOT CHECKED!

Furthermore activate the little sRGB Button in the vray framebuffer and for the Maya Render View go to Display and activate 32Bit floating point HDR (maya restart required)
Output-Format OpenEXR of course.

For the diffuse colors (if not pure colors) use a gamma correct node with 0.455 0.455 0.455
for diffuse texture files activate texture input gamma in attribute editor -> attributes -> Vray -> "Texture input Gamma" leaving the values at default
We do not correct bump, reflection, refraction etc. colors + textures.
HDRs+EXR aren´t corrected either of course.

If u use a 8bit image in the background slot of the vray environment it needs correction as well.

Our compositing department so far never complained about the output files not being linear
Hope I didn´t miss anything.

[bazuka]

@Rich

yes ur right i forgot to tell u to turn on the Dont affect colors

[Reaversword]

No, Texture Input Gamma its only for diffuse (color) textures. Leave the others without it.

[Richard7666]

Our linear workflow involves the following:

Render Settings -> Vray Common
-> "Convert image to sRGB for RenderView" CHECKED

Render Settings -> Vray
Dark Mulitplier : 1
Bright Multiplier: 1
Gamma : 2.2

Affect Background -> CHECKED
Subpixel Mapping -> off by default, but check if needed
Don´t affect Colors -> CHECKED
Linear Workflow -> NOT CHECKED!

Furthermore activate the little sRGB Button in the vray framebuffer and for the Maya Render View go to Display and activate 32Bit floating point HDR (maya restart required)
Output-Format OpenEXR of course.

For the diffuse colors (if not pure colors) use a gamma correct node with 0.455 0.455 0.455
for diffuse texture files activate texture input gamma in attribute editor -> attributes -> Vray -> "Texture input Gamma" leaving the values at default
We do not correct bump, reflection, refraction etc. colors + textures.
HDRs+EXR aren´t corrected either of course.

If u use a 8bit image in the background slot of the vray environment it needs correction as well.

Our compositing department so far never complained about the output files not being linear
Hope I didn´t miss anything.

Cool, this is the workflow I've used in the last image I posted. However, I don't have the sRGB button enabled in the vfb; when I hit that button the result becomes very washed out (the same as it appears in the second render, the one where I didn't hit 'don't affect colors').
Should I be getting such a washed-out result when applying sRGB? It's easy enough to correct with curves in either the VFB or Photoshop of course, but is it correct in the first place? Because I see most raw renders don't look as washed-out as mine with sRGB applied.

Also, using a gamma node at .4545 on my diffuse colours makes them appear different between the hypershade, viewport, colour palette and the final render. See the first image I posted; that light beige/brown is what I've picked in the gamma correct node's colour palette. However in the material attributes, viewport and hypershade, it shows as a rich dark brown. So it makes it very hard to judge.

EDIT:

people in this thread http://forums.cgsociety.org/showthre...f=87&t=1060588 such as Dave Girard say to gamma correct reflection, refraction textures too. Basically anything that affects colour. The only 8bit textures not to correct are things like bump and so on.

[Dariusz Makowski (Dadal)]

Didnt read entire topic but all you have to do it

Start maya
Pick vray as render
Load texture apply either Utility node>gamma>0.4545/0.4545/0.4545/ or vray input gamma node 2.2 or 0.45(cant remember)
Then in vray frame buffer use SRGB
Save to openEXR

That is all you have to do.

[Reaversword]

people in this thread http://forums.cgsociety.org/showthre...f=87&t=1060588 such as Dave Girard say to gamma correct reflection, refraction textures too. Basically anything that affects colour. The only 8bit textures not to correct are things like bump and so on.

It makes sense.. Maybe I should do some changes in my own scenes. But yes, bumps, displacements, blend weights, etc.. shouldn't be gamma corrected, but reflection/refraction color textures I don't see why it shouldn't. I have new doubts!, I'm gonna try it.

[Dariusz Makowski (Dadal)]

U should correct ALL 8/16 bit files! Only 32 bit files dont need correction HDR/EXR. Everything else NEEDS correcting.

[Reaversword]

DADAL, lets see an example:

In Reflection Amount of a VrayMtlMaterial imagine you've a texture with a part at 0.2 grey (20% reflection), part with 0.6 grey (60% reflection) and part at 1.0 (100% reflection).

Vray will respect this values "reading" the map. As is. If you compensate it, you'll loose this values, and the reflection amount control. Vray expects a range from 0 to 1 for this channel.

Or Am I wrong?.

[Dariusz Makowski (Dadal)]

8 and 16 bis images by default have inbeded gamma of 2.2. As we want to work in linear (1) we have to degama all 8/16 bit images to 1. So thats why we use maya gamma node with 0.45454545 to degama the 2.2 to 1.0. We have to do it on all 8/16 bits textures. No matter what we use it for. In vray I think I was just using vray build in gamma correction cant remember haven't used it for a while.

[Reaversword]

I remember that when you use a camera for take a photography, camera is producing an image which gamma you should correct, the same for scanners, etc.. but when you want to control the reflection amount (not the color), you use a number, usually from 0.0 to 1.0. If you want define "regions" with different amounts in your textured object, you create a texture with this different parts with differente values, not with the eye, but with a photoshop/gimp color info. I mean, the range of the image for this purpose is from 0.0 to 1.0, not a brutal hdr range. So if we talk about this "reflection texture" in HSV, I believe the V (valor) should be from 0.0 to 1.0. H and S, the truth, I don't know...

The parameter you cant remember is in the file node texture > attributes > Vray > Texture Input Gamma.

[Dariusz Makowski (Dadal)]

I never hear of having to gamma correct any camera/scanner images ever. If u use 8/16 bit images and they have imbeded gamma 2.2 u HAVE to use gamma corection. Unless those images DONT have gamma imbeded. It dont matter if u use it for reflection bump normal or what ever else you have. HSV is 0-1 or 0-255. HSV = RGB in basic just different control of attributes.

HSV
H = hue
S = saturation
V = value (brightness)