Linear workflow, Vray, and Maya


#55

It’s kind of a mess isn’t it.

From what I understand on all the Max V-Ray linear workflows, its simply a matter of this. One setting which affects everything correctly including swatches.:

Why this can’t be brought to Maya after the fact, I simply cannot comprehend it, or more probably rather, I fail to underestimate the challenge in adding this to Maya??? Not sure.


#56

Yeah max has got it right. Annoys me every time I see it.

Vray intergration in maya is a bit messy to - Extra attributes rather and a vRay AE template menu addition. Vray shaders mixed in with maya shaders rather than getting there own tab. Names look more like proc names than actual names… :argh:
Oh well.


#57

I think Vray in maya is integrated pretty well a lot better than MR … now of course it can be improved but LWF is better and easier doing in Vray than MR I believe … I agree that vray could have his own tab …


#58

This is the 3th day on the internet trying figure out the correct workflow on V-RAY. :banghead:

I am having strange contrast issues(I did not get this thread till today). http://forums.cgsociety.org/showthread.php?p=7424677#post7424677
ChaosGroup Thread - http://www.chaosgroup.com/forums/vbulletin/showthread.php?70055-Linear-Workflow-switch&p=561535#post561535

And here are my tests (I started out testing ply to vrmesh converter and landed on LWF):-

1st image:- http://img31.imageshack.us/img31/1897/linerh.jpg

2nd:- http://imageshack.us/a/img545/5387/capturebgi.jpg

3rd:- http://imageshack.us/a/img594/769/newde.jpg
a little more Hi-Rez - http://imageshack.us/a/img821/6766/compilec.png

4th:- http://imageshack.us/a/img594/7205/neweq.jpg (this was just to get clarity on “affect swatches” check box).

NOTE: I haven’t added a .454 gamma node to my swatch in any of my renders, nor have I selected “convert images to sRGB for rednerView,” instead I am using Maya’s RenderView’s color management and kept the “image color profile as Linear” & “Display Color Profile as sRGB” !! I am not facing any prob, in fact I get 99% as Vray’s frame buffer when you turn the sRGB switch on. Here are the test images with settings -
http://imageshack.us/a/img38/4012/rednerset.jpg

1 point i kept emphasizing on threads here and in ChaosGroup was that…
In Gnomon’s recent tutorial, by R.Nederhorst on Archetype, he keeps the LINEAR WORKFLOW button checked on, not saying that his methods are the final verdict but he seems to render with no problem, though he uses a tiled .exr format for this textures and uses gamma node with values he feels gives GOOD contrast and uses the color balance as well.

Also in this particular tutorial he uses LWF switch turned on http://www.youtube.com/watch?v=bKpTs2qoLqE&feature=player_detailpage

Was also wondering why SePu used CLAMP OUTPUT in his settings on this thread http://forums.cgsociety.org/showthread.php?f=87&t=1060588&page=1&pp=15

EDIT:-

I made a mistake, R.Nederhorst on Archetype does not use LINEAR WORKFLOW button, got confused with his V-Ray Primer documented in which he has turned on LINEAR WORKFLOW button


#59

Forgive me for contradicting about MR, I might be naive…nonetheless here’s my thought after reading through this thread. :curious:

In Mental Ray -
(1) You change the setting under color management,
(2) and under texture file node (depending on what you have set as input under color management),
(3) render window for viewing properly
(4) add .454 gamma node to swatches…!!
(5) rendering in 16 bit or 32 bit exr or similar linear supported format…DONE!! (hope I didn’t miss anything)

In V-Ray-
(1) Turning on all the buttons under color mapping and setting Gamma to 2.2
(2) Adding a texture and selecting the bit map input gamma under Vray extra node for 8-bit files
(3)sRGB button for V-Ray Frame Buffer
(4) Adding .454 gamma node to swatches
(5)rendering in 16 bit or 32 bit exr or similar linear supported format

How is it easier than Mental Ray, when we are following “almost the same procedures” to make things work properly in LW.Flow?

We still add .454 gamma in vary just like mental ray, we still need to specify it to V-Ray about 8-bit images…!!
I might have made the point completely wrong, it’s been just 3 weeks I am using VRay, but its something that occurred to me while reading through. So apologies if I wrote something stupid as like all, even I am a bit confused regarding this after reading and watching different methods on the web. And will Appreciate it if some clears this WORKFLOW issue.
THNX


#60

Frustrating isnt it. All we need is Chaosgroup to officially clarify how their software works. I intend on writing them on Monday but till then - I’ve been thinking about it some more.

That Linear workflow button … My original thought was that all the shader results would be gamma’d - and it certainly appears to do that. If using a mixture of 8bit and 16+bit textures I thought it might cause problems. But then I found this…

http://www.arseniytestin.com/index.php/vray-linear-workflow-explained.html

and to quote:

The mystical ‘linear workflow’ button on whose meaning everybody (even Vray manual itself °O° !) just glisses or throws in some dodgy ban. Well it is there and it does the whole job. Surprisingly it Can tell the sort of map is being processed (color, normal, hdr, bump) and adjust things accordingly.

If that is so that it is smart enough to know what to correct and what not to correct - that let me think some more about why they say don’t use it.

I think it’s basically this. The linear workflow button, where appropriate will remove perhaps only remove using gamma. This is not the same as us removing sRGB from our image using the added attributes on a file texture node. This means the only “correct” way to remove is NOT to use the linear workflow checkbox - and instead use the added vray attr on file textures.

I unfortunately do not have vray access right now so I can’t test this - but regardless when I get a reply from Chaosgroup I will clarify it here.


#61

revilo3D I did post a thread in ChaosGroup regrading this…!!

http://www.chaosgroup.com/forums/vbulletin/showthread.php?70055-Linear-Workflow-switch&p=561535#post561535

EDIT:-
[B]So finally doing few tests after reading this forum…
I got it solved.

LWF button does affect the render in someway, that is the diffuse channel seems to darken, it does apply (.454 gamma), someone did say that.
Thank GOD !! [/B]


#62

The .454 you are preparing the texture for a gamma workflow of 2.2… That part is not even about controlling the gamma.

The best way to say it is a img, in maya is defined has “linear” . . . but the thing is… IS your monitor or system you have by default set for maya “linear”?

A good example is, if your using a old type of mac, its default gamma is of 1.8, so will maya read now as 1.8 gamma as linear?

1/2.2 = .454 (or something like that…)
1/1.8 = .555 (or something like that…)

so lets imagine mayas “default” linear workflow is set up for the majority of monitors, hence gamma 2.2, but your system linear read is 1.8 gamma.

What if you are in a studio with a custom colorspace?

^.^
Joe


#63

Ive tested the linear worfklow checkbox here at work and it appears that it corrects:

a) material swatches
b) incoming connections

…with the inverse of the gamma setting on the colour mapping rollout. Therefore this button will not technically correct sRGB textures perfectly. For full CG work though this is really close enough and if intergration is being done - be more careful. If you pass the backplate back through the renderer and use it - it will not be correct.

OPTION A (Longer but more accurate)
(1) Set gamma 2.2 and choose do not affect colours.
(2) Adding a texture and selecting the bit map input gamma under Vray extra node for 8-bit files - sRGB
(3)sRGB button for V-Ray Frame Buffer
(4) Adding .454 gamma node to swatches
(5)rendering in 16 bit or 32 bit exr or similar linear supported format

OPTION B (easier but less accurate)
(1) Set gamma 2.2 and choose do not affect colours.
(2) Check linear workflow checkbox
(3)sRGB button for V-Ray Frame Buffer
(5)rendering in 16 bit or 32 bit exr or similar linear supported format

I think i got that all correct :slight_smile:


#64

According to earlyWorm, in an other thread…this method we are doing is a wrong workflow.

http://forums.cgsociety.org/showthread.php?p=7424677#post7424677

The last post in 1st PAGE


#65

Nope sounds right.

If your referring to the color mapping gamma attribute - 2.2. See my reply in that thread.

Image sampling optimisations is controlled largely by color and contrast. If your image is linear (dark) it might for example undersample the dark edge of a cube in shadow. When we apply a sRGB LUT it will be potentially become a visible issue.


#66

Quick question; assuming I’m not using the “linear workflow” checkbox*, do I also want to add a Texture Input Gamma attribute (at 2.2) to file textures used for reflection and translucency (on a vray2sidedMtl)?

*note in the render globals Color Mapping drop-down I have Gamma at 1, and ‘don’t affect colors’ unchecked (using sRGB button in the VFB to preview)


#67

NO, linear workflow does not add Gamma attr to tex input node…

the gamma attr node should be added only to color tex, if i remember…


#68

So it works at the material level, correcting whatever is in the diffuse slot I take it. Not at the file node level?

Because I noticed that I got slightly different reflection results when only using the check box, vs using no checkbox but gamma correcting only the diffuse texture.
I will post pictures later to show what I mean.


#69

http://www.thegnomonworkshop.com/store/product/1022/#.UTNSn4XK7ww


#70

I know this is old thread, but something interesting from CHaos forums recently:

This is posted by a Chaos Group developer talking about “linear workflow” checkbox:

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!

I guess the same would translate to Maya and manually gamma correcting.

The only thing to remember is that the linear workflow checkbox will not apply gamma correction to environment slots, as a texture for the lights and V-Ray light material and some other things like car paint material. Its pretty obvious when it happens anyways.

So there we have it. :eek:


#71

Hey thanks for posting that.

Recently I read that we need to gamma correct our light’s slots as well, now i saw a video in i believe cinema4D, where your light slot is also gamma corrected.
How important is that in VRay in Maya?
Any idea anyone?


#72

Yes, if you use Linear Workflow checkbox, I believe you still have to gamma correct a texture if you are plugging it into a light. From what I gather from CHaos said anyway.


#73

Right!

However I am talking about the light swatches - not texture inputs into them


#74

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