(Closed) [HOU-1726] Acescg primaries mode in Houdini

[Hannes Drossel]

Hi!

Is the Acescg primaries mode available in Houdini and if so how do I enable it?

/Hannes

[Hannes Drossel]

Im referring to this setting available in 3dsmax

 
 renderers.current.options_rgbColorSpace = 2

[bdancer]

I'll add a hidden attribute in tomorrow nightly build, could be set like:

hou.parm('/out/vray/rgb_color_space').set("2")

[LeoYfver]

bdancer could be visible too, or is it a reason it will be hidden?

[bdancer]

I'll double check if this could be visible.

[Hannes Drossel]

Thank you!

Do you know if this will affect the look of the new hair shader?
Im hoping the melanin/pheomelanin stuff will be outputted in acescg instead of srgb.

Cheers!

[Hannes Drossel]

Could this be set using an environment variable? So that artist do not need to bother setting it in their scene?

[docaml]

Hmmm, can someone explain what are acescg primaries, mostly, what "primaries" refers to?

[Hannes Drossel]

Hi bdancer!

Is this feature implemented yet? Using version 43001, ff08c27 and cant set the parameter using python and I cant find it among the hidden parameters on the vray renderer node.

[Gosho.Genchev]

Hey, Hannes Drossel ,

please grab a new nightly build tomorrow - we did some code optimizations that caused instability and decided to remove the builds from March 06 to March 10 so you guys don't end up with constant issues. I hope we'll be able to start the nightlies tomorrow, or the day after.

All the best!

[Hannes Drossel]

This is working! Thank you!

It also affects the look of the hair shader. Great! That was what I was looking for!

Cheers!

[Hannes Drossel]

Darn it!

Actually the look of hair shading is not affected by this setting. Reason why I thought so was because I had a light with temperature shining on the hair. The temperature on the light was correctly outputted into acescg but not the output of the melanin/pheomelanin.
The problem for us is that the hair shading is a lot too saturated when using the standard ACES 'output - sRGB' view transform.

Is this a Houdini thing or is this happening in other apps as well?

[Hannes Drossel]

Here are some images showing the problem.
Left is a grid with a vray temperature texture on it. Right is a hair curves object with a hair shader assigned to it.


RGB Color space: sRGB
View transform: VFB standard sRGB view transform




RGB Color space: ACEScg
View transform: VFB standard sRGB view transform

Note that the temperature texture rgb values are outputted in a the correct color space. Hair shading remains unaltered which is incorrect.



RGB Color space: ACEScg
View transform: ACES Output sRGB using ACES OCIO config

This is how we are looking at our renders. Hair shading is very very saturated and unusable at this point. Temperature is looking great though!

Is there something you can do about this?

[Gosho.Genchev]

Hey, Hannes Drossel ,

those float parameters are indeed not handled, I've logged it and messaged the developer. I'll ping you once a solution is implemented.
I was hoping to be able to give you a work-around but hit a wall there as well - we'll have to add support for conversion of the color pickers. We'll try to get this working as soon as possible.

Thank you for bringing this up!

[docaml]

But how do you change primaries into ACES? Environment variable, right? What is the proper workflow? Any help...