V-Ray Next Update 3 and ACESCG colorspace parameters

V-Ray V-Ray for 3ds Max General
1

Hi there!

I’m trying to set up ACESCG workflow for 3ds max and V-Ray Next Update 3 and having some trouble figuring out the correct way. It says in the update changelog:

(*) V-Ray: Add a renderer parameter “options_useColorSpaceForBitmaps” that tells all VRayHDRI maps to determine the color space from the file name;

But where can I access this parameter?

Also VrayOCIO map has a checkbox “from basemap filename” but if I input a basemap, say bitmap with “sRGB” in the filename and activate the checkbox it puts aces in and ACEScg out in the ColorSpace Parameters which is wrong? What are the keywords besides “sRGB” for determining the basemap filenames?

Also I’m unsure if I need to activate support for ACESCG via maxscript in V-Ray Next Update 3 or not? Meaning switches:
renderers.current.options_rgbColorSpace = 2
VRAY_SHOW_COLOR_SPACE_UI=1

Best,
Mika

2

Here is an explanation of the parameters as well as the set up for the ACES workflow:

1. Name your textures according to their color space (i.e. color_srgb.exr, color_acescg.exr).
2. Load these textures in VRayHDRI maps.
3. Open the ScriptListener (F11) and write the following commands:

vr=renderers.current
vr.options_useColorSpaceForBitmaps=true

This will tell V-Ray to determine the color space of VRayHDRI maps from their filename. There are two variants:
a) If an OCIO environment variable is set (OCIO=path/to/config.ocio), the color space will be determined from a file name that matches a color space name in the loaded configuration.
b) If there isn’t such a variable, the color space will be determined from a file name containing the ‘acescg’ or ‘srgb’ keywords.

4. In the ScriptListener write the following commands:

vr.options_rgbcolorspace=2

This will tell V-Ray to set the internal color grading system to ACEScg (1=sRGB, 2=ACEScg) and will affect internal V-Ray components such as white balance, VRaySun, VRayHDRI (if the upper mentioned parameter is true), etc.

5. In the VFB, disable the sRGB space and load the ‘config.ocio’ file (or automatically detected via the OCIO environment variable)
6. Set the ‘Input Color Space’ to ACEScg. Set a ‘View Transform’ as needed.
7. When saving PNG/JPG and using the ‘Save in image’ in the OCIO options, make sure you save with a gamma override of 1

Note that this is not our final ACEScg workflow. This process will be simplified in future V-Ray builds and it will have its own UI. Here is a link with a sample set scene: http://ftp.chaosgroup.com/support/aces_workflow_2017-2020.7z

EDIT:
-Re-saved the sample scene for older 3ds max versions
-Changed the parameter name from ‘vray’ to '‘vr’ to avoid read-only variables.

3

Any chance you can save this down max 2019?

Thanks

4

@DanSHP Certainly, here you go: http://ftp.chaosgroup.com/support/aces\_workflow\_2017-2020.7z

5

Hi.

None of those commands in listener seem to do much. I just get unknown property errors. Any ideas?

I’m running next update 3.

"vray.options_rgbcolorspace=2
-- Unknown property: “options_rgbcolorspace” in V_Ray_Next__update_3
-- MAXScript callstack:
-- thread data: threadID:12920"

6

Sorry, ‘vray’ seems to be a read-only variable. Just replace it with a parameter of your choice when setting the current renderer (i.e. vr=renderers.current, etc.) or simply use i.e. renderers.current.options_rgbcolorspace. I’ll edit the main post to avoid further confusion.

7

Thanks Aleksandar

8

Sorry to be a pain, but following your instructions as detailed in the edited guide above still returns errors in listener.

> r=renderers.current

vr.options_useColorSpaceForBitmaps=true
-- Unknown property: “options_useColorSpaceForBitmaps” in undefined
-- MAXScript callstack:
-- thread data: threadID:28896

EDIT: Think I made a mistake here and typed the commands without pressing enter after each line! All working now.