ACES with 3ds max

[JulianD]

Hello everyone,

I read a lot about ACES recently and when I looked up on the forum I could only see some info here and there but no real post.
This is a bit disappointed because let's be honest: colorspace, gamut, OETF/EOTF, ... are not easy to understand at the first glance, and when I come to set up a OCIO on 3d software that doesn't have a color manager system, it's even worse.

So this is the place where we can set up a good ACES workflow on 3ds max together and help each other.


For my concern, I'm using ACES 1.0.3 with V-Ray Next (update 2) on 3ds max 2020.

As far as I know, on 3ds max, there are 2 steps:
1. -> Convert your textures to ACEScg
2. -> setup your OCIO profile


1. CONVERTING TEXTURES TO ACESCG COLORSPACE

For my next example, I used a 8bit jpg file in Linear sRGB colorspace.


I used a photography as a texture just to see how shadows/highlights/skin tone changed with ACES.
I thought it's a good starting point as humans are good at seeing skin tone so we could see the changes better (at least more than in a concrete albedo). Let's say she's my Marcy.


I loaded my texture with a VrayHDRI map, set the color space to sRGB.
Then, I plugged a VrayOCIO node as shown:


So, we have a jpg file (Linear sRGB colorspace) and we want it to be converted to ACEScg. Sounds about right.



At this point, I think I'm good even though my texture seems darker... Let's skip to step 2.


2. OCIO IN VFB
Now, let's set up our OCIO profile in the VFB.


Alright: All our textures are converted into ACEScg and my monitor is in sRGB colorspace. Let's render!


RENDER (diffusefilter pass):


Mmmh.. Something looks wrong here. Seems like there's a 2.2 gamma curve applied to it or something..

What did I miss?


Cheers,

[joconnell]

Display device should be a monitor profile like srgb, gamma 2.2, rec709 or similar, view transform is for things like a lut / look / grade that you're supplied from a colourist to add the "style" to the footage!

[JulianD]

Display device should be a monitor profile like srgb, gamma 2.2, rec709 or similar, view transform is for things like a lut / look / grade that you're supplied from a colourist to add the "style" to the footage!

Display device only gives you "ACES", there's anything else.




View transform gives you a list of colorspaces so I thought it was the one you use with your monitor

vray manual:
View transform – Specifies the viewing transformation.





If it was a LUT loader it would have "none" in the list to turn it off, but it doesn't.

[psanitra]

- if you load jpg and set VrayHDRI map loader to sRGB as you did, then you already linearized the image(from 2.2 to 1) and should set the Aces input tranform to Utility - Linear sRGB
- if you load jpg and set VrayHDRI map loader to None, then you should use Utility - sRGB Texture.

If you use ACES - sRGB as view transform, it`s normal to get a bit more contrastly image, view transform is "S" shaped curve, it will crush blacks and compress highlights. If the crush is too much for you, you can use rec709 as view transform, that gives more room to the shadows..

[joconnell]

Apologies for jumping in with both feet, I'm on 3.6 here and we have display device as our monitor profiles and then view transform for the grade on our footage.

[JulianD]

- if you load jpg and set VrayHDRI map loader to sRGB as you did, then you already linearized the image(from 2.2 to 1) and should set the Aces input tranform to Utility - Linear sRGB
- if you load jpg and set VrayHDRI map loader to None, then you should use Utility - sRGB Texture.

Yes, that's what I understood once I read the manual so I decided to make a second experiment.

Nota: "colorspace" in vrayhdri should definitely be renamed "Transfer Functions", because that's what it does: OETF / EOTF / none Transfer Function.





Now my highlights seem blown up, and I'm stuck here, I'm out of ideas. Everything seems well set up at this point.

If you use ACES - sRGB as view transform, it`s normal to get a bit more contrastly image, view transform is "S" shaped curve, it will crush blacks and compress highlights. If the crush is too much for you, you can use rec709 as view transform, that gives more room to the shadows..

I disagree. I use a sRGB monitor, why would I jump to another colorspace if I'm watching my render on my screen at the end? I can sometimes have a look at DCI-P3 to see how it would look like in a cinema, but it can't be the reference for my display target.

[psanitra]

Sure, you can disagree, but it`s not going to change the fact that with sRGB view transform you going to get blacks crushed. And you will need to find a way how to check your dark areas in renders/shaders/setup when working in max. You can do it with VFB rising exposure, with curves, level or whatever, but me personally find it easier to flick to rec709 for few seconds when i need to check dark areas.
It`s not a big deal, i`m sure you know it`s just view transform, it`s not baked into actual data/exr, you still work in same setup/lightning conditions. I use ACES workflow for close to 2 years now, in can be a pain sometimes, but don`t fight it, adapt or dont use it

[muoto]

When i tried out Aces, i used the rec2020, which made the whole image more softer and got nice colours.

But the workflow is this not so easy to set up, and i finally ended using a 3Dlut that kind of mimicks the same curves corrections, which works kind of.

And i can save directly to jpg from the vfb

[stevejjd]

I would love to see a full guide on setting up a proper color pipeline. Maybe this could be possible when the new VFB comes out with full support of ACEScg.

[^Lele^]

I disagree. I use a sRGB monitor, why would I jump to another colorspace if I'm watching my render on my screen at the end? I can sometimes have a look at DCI-P3 to see how it would look like in a cinema, but it can't be the reference for my display target.

I had to make a whole movie viewing my renders in Log space on an sRGB monitor, so things can definitely be done head over heels, and come out fine.
I'd still vote for a *linear*, scene referred pipeline, and would let compers do their stuff later, in the right environment.
If i have to double a light's intensity, it'd better double, exactly, in my renders, or madness would ensue.

you'll notice i am not alone thinking this:
https://www.lightillusion.com/aces_overview.html
"Scene Referred is also often in Linear Light, which while suitable for computer graphic rendering, is not suitable for grading workflows."

[JulianD]

I had to make a whole movie viewing my renders in Log space on an sRGB monitor, so things can definitely be done head over heels, and come out fine.
I'd still vote for a *linear*, scene referred pipeline, and would let compers do their stuff later, in the right environment.
If i have to double a light's intensity, it'd better double, exactly, in my renders, or madness would ensue.

you'll notice i am not alone thinking this:
https://www.lightillusion.com/aces_overview.html
"Scene Referred is also often in Linear Light, which while suitable for computer graphic rendering, is not suitable for grading workflows."

I totally agree with that and I never meant the opposite, don't get me wrong. What I said was: once you know your display target you don't need to check another one because it will never fit your final image. Now, jumping from sRGB to Rec709 won't get you far from your final result, so yes you could "cheat" that way if it helps.


Does anyone have more information regarding the "from basemap file name" part of the VrayOCIO map ?
from basemap file name – When this option is enabled, the texture will try to determine the correct in/out color spaces based on the file name from the base texture (assuming it is a Bitmap or VRayHDRI texture).

I tried many keywords (I even name my texture simply "sRGB.jpg") but it always puts "aces" in the "in" slot. There is no info on the manual.. What are the keywords for "Utility - Linear - sRGB" and "Utility - sRGB - Texture" please?
Thank you !

[^Lele^]

JulianD we're in agreement.
One thing i should state for completenss's sake, is that in AcesCG one would get benefits well visible under sRGB display, for example in GI (or any other such many-bounce effect, like SSS): here, the demultiplication of intensities, coupled with the hue changes as different surfaces are bounced upon, will benefit from the bigger primaries of the colorspace, resulting in somewhat fuller colors.
The standard is maturing, allright, albeit at somewhat slower pace than ideal, i think.

[hermit.crab]

Does anyone have more information regarding the "from basemap file name" part of the VrayOCIO map ?
from basemap file name – When this option is enabled, the texture will try to determine the correct in/out color spaces based on the file name from the base texture (assuming it is a Bitmap or VRayHDRI texture).

I tried many keywords (I even name my texture simply "sRGB.jpg") but it always puts "aces" in the "in" slot. There is no info on the manual.. What are the keywords for "Utility - Linear - sRGB" and "Utility - sRGB - Texture" please?
Thank you !

The keywords are taken from the loaded configuration - i.e. if you've loaded the aces_1.0.3 configuration file, the sought after names should be "lin_srgb" and "rgb_texture" (i.e. "image_lin_srgb.exr"). You can see all the color space names in the dropdown menu of in/out colorspace parameters.
It may be useful to know that we are working on a better way of approaching the ACEScg workflow without the use of OCIO textures - more detail on the matter in this thread: https://forums.chaosgroup.com/forum/...10#post1055410
Note that the approach is not final, it will be simplified in future V-Ray builds and it will have its own UI.

[JulianD]

JulianD we're in agreement.
One thing i should state for completenss's sake, is that in AcesCG one would get benefits well visible under sRGB display, for example in GI (or any other such many-bounce effect, like SSS): here, the demultiplication of intensities, coupled with the hue changes as different surfaces are bounced upon, will benefit from the bigger primaries of the colorspace, resulting in somewhat fuller colors.
The standard is maturing, allright, albeit at somewhat slower pace than ideal, i think.

For now the results I got are OK, I was actually expecting more GI colored bounces on the sides of my spheres to be honest. But it's just a box and a couple of spheres after all so, let's wait for more tests.






@aleksandar.hadzhiev:
Can you tell me more about this parameter please "options_rgbcolorspace=2" ? What does it do on lights and GI?
I rendered my cornwell box with rgbcolorspace=2 and rgbcolorspace=1 and saw no difference. Is it only working with textures? (All my colors are vraycolor map)

Also do you know when the new VFB (with full aces workflow) will launch?
Thank you

[^Lele^]

I think that's because the colors are more saturated under AcesCG, and so they tend to drown the fainter ones from the bounces, at least in this example.
The lower range of the sRGB primaries allows for more bounced green/red to show through.
You'll notice against gray both the bounced reds and bounced greens are far stronger than under sRGB.