Correct Linear workflow in Max & Octane Tweet

[designandcode]

Hi everyone,

I've been reading a lot on linear workflow with Octane & Max and am a bit confused.

Right now, I've got the following settings:

- Nonlinear tonemapping is off, no response curve
- 3DS Max gamma hack is off
- 3DS Max Gamma/Lut Correction is on and set to 2.2
- I've changed my image textures Gamma to 1.0 from 2.2

Is this correct?

Do I need to turn on the gamma hack or turn off Max Correction?

I also found this very confusing Linear workflow for C4D manual here: LINK which says to turn on Nonlinear tonemapping and set the response to SRGB - am I supposed to do this in Max as well?

[paride4331]

Hi designandcode,
https://render.otoy.com/forum/viewtopic.php?f=27&t=65075&p=330416&hilit=+linear#p330576
https://render.otoy.com/forum/viewtopic.php?f=21&t=33214&p=143802&hilit=+gamma#p143144
Regards
Paride

[designandcode]

Hi Paride,

I have read both of those threads and have downloaded the example file previously. The example file has the 3DS max gamma hack enabled, which elsewhere in the forum is said to be wrong when using linear workflow. The other thread about linear workflow makes a lot of references to settings that I cannot find in Octane for Max, e.g. "The gamma slider in the tone mapping settings is the intended display gamma" - if this is supposed to be the gamma under Camera > Imager > nonlinear tonemapping, that thread says I should set this to 2.2 - this is super confusing and seems wrong. It is set to 1 in the linear workflow example file. Can you please give 3ds max specific instructions for linear workflow and answer the following questions:

1) 3ds max gamma hack - on or off?
2) Camera Imager off or on, if on, what settings?
3) 3DS Max Gamma correction off or on & what settings?
4) Image textures set to 1.0 Gamma or left at 2.2?

[paride4331]

Hi designandcode,
camera imager in Render setup works with 3dsMax standard camera only.
Octane camera imager is in Octane camera panel (press H and select the Octane camera you want).
I understand all your questions, but Octane works in linear, there are no issues like other render engines.
The file you download allows you to work in linear, but when you save your render, obviously it must be .EXR format.
Regards
Paride

[designandcode]

Hi Paride,

I've done a few test renders from the gamma file (exr @32). If I render simple diffuse, reflection, transmission etc passes, I can put the beauty pass back together.

If I render raw passes with diffuse & diffuse filter, it doesn't work in the gamma file you linked to. The raw diffuse pass comes out extremely overbright, and when I try to multiply it with the Diffuse filter, it will not let me.

However, if I disable 3Ds Max Gamma Hack & set the Octane Camera Imager Gamma to 1.0 instead of 2.2, it works as expected.

What is going on here? Why is this happening and which settings am I supposed to use then?

[paride4331]

Hi designandcode,
opening .exr you should set Gamma 1.
Regards
Paride

[designandcode]

Hi Paride,

I have used exactly the same settings as you. Full float 32 .exr with no compression, and when I open it in Photoshop set Gamma to 1. I still get those completely overblown passes when I render raw beauty passes. When not rendering raw it is fine, but raw is going wrong.

I'm attaching the .exr file so you can see what I mean. The diffuse pass is unusable and blown out.

[paride4331]

Hi designandcode,
I see, but it not happens with my workflow, I don't know why.
Try take a look on my setup, maybe something different.
Regards
Paride.

[thekwen]

Just to say, correct me if i'm wrong but exr is a native 2.2 gamma.
So if you save you exr with gamma 1 you get a 2.2 gamma.
If you save your exr with gamma 2.2 you get 2.2*2.2 gamma.

Kwen

[designandcode]

Hi Paride, the only difference is here:

01.jpg (8.39 KiB) Viewed 4412 times

I have checked the raw button because if I do not, I cannot render Diffuse pass & diffuse filter pass like described here: LINK

If I do not check the raw button, I get simple diffuse, reflection etc passes which look fine and not blown out, but I'd like more flexibility when compositing.

If I do have Raw checked like above, I get the blown out pass. I found this somewhere in the forum from when the raw passes was first released:

We added the possibility to render raw and filter beauty passes, which can then be multiplied during compositing, which allows you to modify the colour of objects in post (of course, reflection of changed object will still show the old colour). The calculation of the raw passes is done during tonemapping which means it works only if you use the linear response curve with a gamma of 1.

This sounds to me like setting the gamma to 2.2 in the Imager is the problem?