Disable Max Gamma Correction and use VRay's LWF button?

[jpmartin]

I thought I had the LWF process down and long behind me until I read this statement from Svetlozar in a different thread here on the forums:

"...the best way to work with LWF at the moment is to use Linear Workflow ON and Gamma - 2.2 from Vray Color Mapping Rollout and to disable 3DSMax Gamma."

http://www.chaosgroup.com/forums/vbu...494#post550494

I thought this statement was very intriguing, so I gave it a shot, and get some noticeably different results between the "Traditional" 3D Max Gamma workflow and Svetlozar's suggested workflow of turning off Max's gamma correction and using the VRay Linear workflow option in the color mapping settings instead.

I have to do more testing, but it seems like with Svetlozar's LWF method (disabling max's gamma), colors are more saturated and there is less burnout around windows. However, the overall feel of the image seemed less "realistic" to me. If I have some time, I'll try to post some comparisons later.

Since they produce different results, I'm curious to know if one is more physically accurate then the other.

I know at the end of the day, it is down personal preference and what works best for you, but I'd also like to be confident knowing that the settings I am using will provide me with the most accurate results.

Is anyone bypassing Max's gamma settings and using the VRay Linear Workflow button instead??

Thanks!
-Jesse

[instinct]

Vlado mentioned on the Forums that the LWF Checkbox is meant as a quick workaround to render old non-linear scenes and not suggested for production use.

Regards,
Thorsten

[jpmartin]

Yea, that is what I always thought as well, and never really paid it any attention. However, Svetlozar is from Chaos Group, so I assume he's got the latest and greatest info.


Here's Svetlozar's entire comment on the LWF checkbox:

2.LWF and Gamma - (this is usually very LONG theme) - the best way to work with LWF at the moment is to use Linear Workflow ON and Gamma - 2.2 from Vray Color Mapping Rollout and to disable 3DSMax Gamma. Most of the users are using 3DSMax Gamma but there is one great disadvantage to that - the colors in viewport, material editor and rendered image do not match - no matter if you set "Affect Color Selectors / Material Editor" the problem is still there. Vray Gamma doesn't have that issue - it is just better.
One questions is always asked when I talk about this setup - Why in the help file is written that this workflow is not correct - it is just because there is a tiny difference between Gamma and sRGB curve. Vray Gamma Setup and the 3DSMax Gamma setup are not 100% correct LWF just because Gamma curve is different that sRGB curve - the difference is very very small. At the end Vray and 3DSMax LWF setups will produce the same result - but with Vray setup it would be easier to work with!


Also, when I downloaded the VRayRT benchmark scene a few months back, I noticed that the LWF checkbox was enabled, and thought that was very strange coming from a file produced by Chaos Group.

Then, I recently stumbled on a post where this guy said someone from Chaos Group suggested this same workflow to him... Here is the link:
http://www.arseniytestin.com/index.p...explained.html

Anyway, this has got me really intrigued...

[tashko.zashev]

Hi,

Yes, the approach with Linear workflow checkbox that Svetlozar has posted is working fine and it can be used for all type of scenes.
Just keep in mine that this options doesn't apply revers gamma curve to the maps assigned to the environment slots, as a texture for the lights and V-Ray light material.

[jpmartin]

Interesting. Thanks for the tip. Maybe that is why the illumination seemed so different between the two linear setups.

[tashko.zashev]

In my opinion both linear workflow approaches should produce same beauty pass.
If you have some test scenes for this case, we can check them.

[ARTECONI-CGI]

I agree on everything you say jpmartin.
Personally I prefer the results I get with the Svetlozar method.

Tashko I will add that that the maps for the vrayfastsss2 materials as well don't get corrected. Can't remember which one at the moment. I think it was the overall color one.

I keep on thinking that neither Chaosgroup knows exactly how is meant to be implemented the LWF, I have tried often to ask but never got a straightforward answer, just suggestions to do this or that. I keep on wondering why don't we get it properly documented by the software house. Once and forever.

Giacomo.

[3LP]

I don't want to push it, but I kind of agree.

We don't have the absolute truth on how to do/use the LWF in the best physicly correct way.
We should have one straight answer, and it's up to us/artist after to massage that to sute our artistical view afterworths.

I was convinced to use LWF the right way for months, and now I'm not that sure anymore.
I don't think there is such a confusion in the other renderer where they claim to be unbiased and physicly correct, it just works...
I understand we need to be backworths compatible with older scenes, but this whole thing just mess up with everyone's understanding.

I was going to say, we need a magic button, and it seems like we do (although it had been allways pointed out like "don't touch this!"), but, is that more accurate way?
manly because now with 2014, Autodesk took all the gamma setup out of the UI, so now, I'm even more confused on how we have to set it up, and I guess the LWF button is the way to go then.

In the end, I'm just confused I guess...

Stan

[vlado]

LWF can be done in several different ways, all of them are correct. However with the changes in 3ds Max 2014, we will adjust the future releases of V-Ray to match the 3ds Max settings out of the box, so ideally you should not have to touch any setting at all, no matter if you actually understand what's going on or not.

As for the "Linear workflow option" in the V-Ray color mapping settings - DO NOT USE IT! I already regret deeply for putting that option there because some of our artists asked for it (and they insist on having it there). If it was up to me, I'd remove it right away. The option is inconsistent, where some things will be corrected, some will not and you have to remember each case. Further on, it corrects the final result of an entire shading network, whereas you only need to correct the input bitmaps (and in some special cases, colors - but that's another story).

Best regards,
Vlado

[danb4026]

Vlado,


From what I am reading, I think some users would like to hear what YOU would use as your settings when applying a LWF in Max 2013.

Ex:

MAX GAMMA SETTINGS:

Gamma to 2.2
Affect ME ON
Affect color selector = ON
Input to 2.2
Output to 1.0
(Override gamma to 2.2 on file save to 2.2 when saving as a 16bit or less file format other then exr)

VRAY COLOR MAPPING:

Linear 1.0, 1.0, 2.2
Don't Affect Color = ON

VRAY FRAME BUFFER:

SRGB = ON

The above is an example of one workflow. If this is not your suggestion, the revise to what YOU would use.

[vlado]

I would use exactly the settings that you have described. These will be the default settings in newer builds (although the "Don't affect colors" will be modified a bit, so that you can choose to not apply the gamma, but to apply the other color mapping settings).

I believe that in 3ds Max 2014 you can leave the output gamma to 2.2; 3ds Max will be smart enough to figure out if you are saving to an 8-bit format or to an EXR and will only apply the output gamma in the first case.

Best regards,
Vlado

[danb4026]

Thanks Vlado, hopefully that helps clear things up and simplify the matter.

[jpmartin]

Thanks, everyone, for weighing in here.

It's extremely helpful to have some reassurance that I'm using the right settings!

[ARTECONI-CGI]

Thanks Vlado and all of you guys,

I have a last question and I will be sorted forever about the LWF.
How should I select my colour? As it is or through a vraycolor node?

Kind Regards,

Giacomo.

[ARTECONI-CGI]

Or maybe the vray color is used only to match the photoshop color that are not linearized....?