Long-standing basic problem: white balance

[boxfx]

I've been using Octane for years, but one thing has constantly eluded me. White balance. How can I render a white object, and have it show up as white?

If I take a default scene and add a default plane, with a default diffuse material, then point a default octane area light at it and set the environment to black; I would expect to get a neutral grey/white object. But I don't, Instead I get a significantly blue tint to the render.

If I move the lights white balance to a warmer shade, the blue goes away, but it never turns neutral white, instead it immediately goes into orange. There is no colour-less phase.

So I instead try to use octane's White Point setting. I click the colour picker, click on the rendered plane and octane inserts a shade of pale blue into the white point setting. It gets better, but the render still isn't neutral!, its still blue.

What am I missing? How does one render a neutral grey/white object as having no colour?

If I light my scene with a plain white octane sky, only then do I get a neutral non-tinted render

[elsksa]

Hi, which version are you using?
Octane 2021 has, at the moment, an option to "revert back to the old behavior". Octane versions prior to 2021 are by default using the "old behavior".

It should be achievable in both cases with the old behavior (in the kernel settings, for 2021, by default for other older versions). Octane lights can be set to either "Texture Emission" or "Black Body". The latter will have a temperature, while the other can be set to greyscale via the R'G'B Color node option.

If you are interested:
• Here is a reply from an other forum-thread:viewtopic.php?f=114&t=78573&p=406122#p405407
• Video demonstration: viewtopic.php?f=114&t=78573&p=406122#p406122
• For more detailed information, see the "Octane 2021 updated color processing" section from: https://www.elsksa.me/scientia/cgi-offl ... management

As a tip, I would recommend to inspect the values in the Octane Render View by enabling the Diffuse Beauty (Filter) AOV in Octane.

[boxfx]

Currently we are using Octane 2020.2.5 R3 in C4D R20. We learnt to leave new releases to the other guinea pigs for a few months. This has been a general issue for us going all the way back to Octane 3.00, Octane just fundamentally, by default, renders everything with a cool cast.

You say octane lights can be set to texture emission or black body, where are we finding this in C4D? when we add a standard octane area light panel, it has a temperature slider set to 6500 by default, and there is a texture image/shader slot that can be used, however selecting a basic white octane rgb shader makes no difference to the rendered image.

For reference, this is what we get with a white material and a default octane light, a good 10% blue saturated surface (the material view is just there to show what colour the image is rendering as, the actual octane material on the plane is white):

The simplest way we have found to combat this is to insert a simple octane rgb spectrum of pink into every light, these then render out with neutral greys and whites.

We would have thought that simply setting the white point in the render settings would have been the most obvious option, but this is flawed because A: After sampling our white point, its never strong enough to actually make the blue parts go white, we would need to double the white pointe colour saturation to get close. And B, we have greyscale HDRI environments which do already render perfectly neutral greys, shifting the render white point causes them to start turning pink.

Before and after c4d project files of our basic workaround attached. Are we missing something fundamentally basic in the default.c4d project that is causing all these basic default objects to render so blue?

[elsksa]

Here is a simple scene-breakdown. Let me know if it helped.
A similar result should be achieved with Octane 2021 and its new white light spectrum change (despite having, for now, an option to revert back to the "behavior" from version prior to 2021).

PS: I only have/use Octane Standalone, however, the same can be applied to Octane plugins.

It is also important to keep in mind that Octane is a spectral light transportation model based renderer.

[boxfx]

Thanks for your time, but to be honest this doesn't really help. We never use and have no intention of using octane standalone. We use Octane 2020, 2021 is still in beta and we're not risking that in a commercial environment.

We are aware that Octane is a spectral renderer and understand the pros and cons of that. Really this whole thing is simply a question of: "why doesn't a white light on a white object with blank white balance create a white render?"

Are we missing some element or is the simple fact that Octane 2020 renders everything slightly blue by default unless manually adjusted to do otherwise?

[boxfx]

Testing with c4d R25 and octane 2021.1 R2. Now everything just renders slightly purple. There are no new "white balance" options on the octane light tags as far as I can see.

[Gpix]

Hey everyone,

well, to be honest, it is not as bad as you describe it.

There is a WB Option within the camera imager (like in the real world, you would set the WB in your camera, not in your lights, and I know what I am talking about because I am also working as a professional advertisment photographer for 13 years now, where color trueness is an important factor) but you have to sample the grey-point on the right spot. Like you did when measuring Light-tempartur with an good old Lightometer. Not just clicking on any neutral colored object within your scene.

Just a ntk-fact: The 6500 Kelvin light temperature is truly a thing we can fight over, because high-class quality studio lights have an estimated Kelvin temperature around 5550 Kelvin, which is almost "pure white" light.
But in the real world, you also have slightly variations due to the fabrics you put on for diffusion. Therefore, you have to tweak you WB in-camera. Like in octane.

See attached photo for the WB option inside the camera imager tab within your octane camera tag (pretty sure you know about it, as you described it, but for anyone who looks at the same problem, and doesn't know where this function is.

Hope that helps.

[elsksa]

There aren't any actual problems as the title of the forum thread does suggest.

We never use and have no intention of using octane standalone. We use Octane 2020, 2021 is still in beta and we're not risking that in a commercial environment.

I have never suggested to update to 2021. In both Octane 2020 or 2021, the same result, as what I have shared, is possible. What is available and possible in Octane Standalone, is in the Octane plugins. I am demonstrating Standalone because that is what I use exclusively. I do not have a Cinema 4D license.

Could you set the light the same way as I did and screenshot me the result and a screenshot of the Camera Imager?

Is the Camera Imager set to a "neutral response", without any LUT, OCIO configuration file or similar is used/set?

[AWOLism]

I'm not sure if I'm misenterpreting something, but I believe the solution is, as mentioned, to just switch from Blackbody to Texture Emission in the light settings.
See attached C4D file which is an adjusted version of the file posted above, and a screen shot of Octane Light Tag settings.

[boxfx]

I'm not sure if I'm misenterpreting something, but I believe the solution is, as mentioned, to just switch from Blackbody to Texture Emission in the light settings.
See attached C4D file which is an adjusted version of the file posted above, and a screen shot of Octane Light Tag settings.

Thankyou! truly, thankyou, this is what we were missing. Universally in c4d all the useful settings always start on the third tab of attribute settings, we were skimming over this 'main' tab the same way that you automatically skim past banner adverts on webpages, or cant find the butter in the fridge despite it being at the front of the middle shelf.

We were under the impression that octane being a spectral renderer meant that setting a white balance for the light was mandatory for all lights