No "Invert Direction" for VrayOCIO on ACES 1.3

[mori4h]

We decided to upgrade from ACES 1.0.3 to ACES 1.3 (v2.1 for Vray).

Previously we could convert an srgb jpg loaded on vraybitmap to ACES and maintain the same "visual" of the original srgb jpg. For example when a client sends footage to be introduced in the 3d rendering, but it has to maintain the srgb look in aces. We did that via double VrayOCIO transforms.

However now on ACES 1.3, everything changed. In Nuke we basically have only 2 options, and i attached the screenshots of the nodes. So we can maintain the srgb look in ACES.

Problem is, we don't have the "invert direction" option in VrayOCIO... So we can't do these transformations live in 3dsmax/vray anymore. Maya has this "Invert View" option that seems to work (attached)... But not on 3dsmax.

Is it possible to introduce this option? Or is there any workaround i'm missing?

[mori4h]

Ok so this got me thinking a bit, and i tried saving the OCIO transforms from Nuke into a .3dl file. And then using a VrayOCIO in FileTransform mode... And it works! 100% match with the original sRGB.

So i'm sharing the setup to whoever finds this issue and needs a temporary working solution, while we don't have an inverse direction option.

[hermit.crab]

VRayOCIO has a "Display" mode, with which you can set a View Transform. In your case, you'll need one VRayOCIO for conversion and another for display.

[mori4h]

Hi, I tried what you're saying, but i cannot get it to match. I can in nuke, but the "Display" has "Invert Direction" which the view transform in VrayOCIO doesn't have. Can you share an example? Here's the image im using.

[hermit.crab]

I understand. I logged an improvement request on your behalf (internal bug-tracker id: VMAX-14298 ). Not sure how you got it to work in Maya, though.

[mori4h]

The maya tip wasn't from me, was from someone on the Nuke forums. It seems it's on maya's bitmap options, and not on vrayocio.

[piotrus3333]

without custom ocio config ACES 1.3 will look exactly like 1.2 in VFB.
you are missing OCIO Looks:

[piotrus3333]

this config will help you do what you are after in Max and VRay: colorspace transform from sRGB ACES 1.0 - SDR Video to ACEScg
plus ACES 1.3 ref gamut compress view for VFB.

modified parts:
mP - added ACES 1.0 - SDR Video Look RGC - ACES 1.0 - SDR Video with ACES 1.3 Reference Gamut Compression look
mP - added colorspace sRGB ACES 1.0 - SDR Video

[mori4h]

Hi, thanks for trying to figure this out. I tried your custom OCIO but the problem still persists. I don't think it's the same issue i'm talking about, unless i'm doing something wrong.

The custom 3dl i've made in Nuke is working right now, i can share it here. I have one for live texture conversion, and another for custom background in VFB.

[piotrus3333]

Hi, thanks for trying to figure this out. I tried your custom OCIO but the problem still persists. I don't think it's the same issue i'm talking about, unless i'm doing something wrong.

The custom 3dl i've made in Nuke is working right now, i can share it here. I have one for live texture conversion, and another for custom background in VFB.

I've just double checked with original cg ocio 2.1 config in 3dsMax 2024.
ACES 1.0 SDR video >>> ACEScg is working correctly.

your luts are doing the same but clipping the output at 1.0 float - with that reversed display transform output should reach maximum a bit above 16 float (over 10 float on red channel in your image)