HOW TO: Make a Calibrated Material Scene

[dj_buckley]

Yep - thanks James, I should probably have started another thread, questioning the use of Albedo over normal diffuse maps rather than confuse it with the original post - which I get.

I'd get so frustrated being told by manufacturers things were wrong when their own product would look wildly different when held under different lighting conditions

[James Vella]

I'd get so frustrated being told by manufacturers things were wrong when their own product would look wildly different when held under different lighting conditions

Hah, I know right! This method solved most of those issues once I calibrate each HDRI and keep them desaturated for lighting purposes, however I still have to explain to them in shadow areas it will appear darker (duh!)

Dubcat, I have setup the material as you have above and it come out completely white - until I unchecked "Perform mixing in sRGB space" on all the CoronaMix Texmaps - is this correct?
Also, is the last operation "Dynamic Texture" in overlay mode?

Cheers

Edit:
This is when I set up the material as you have it with "Perform mixing in sRGB space" switched off - which made the blacks too milky


I adjusted the second last node "Compiled" with a gamma of 0.45 which brought back all value as I would expect


Then I switched "Perform mixing in sRGB space" back on for the CoronaMix nodes, and removed the Gamma 2.2 (since a 0.45 at the end is reversing this anyway) and I got closer to what I was looking for... Do we really need to add the Gamma in and then remove it or can we take that step out as I have below? Or did I miss something here


If thats the case, could we simplify it once more to something like this?


edit: My blacks are not even close, Im definitely missing something here

[romullus]

Guys, can we at least settle down on terminology? I get impression, that some are talking about albedo as texture map with removed ambient shadowing and others treat it as colour separated from details component. It's so darn confusing...

Anyways, huge thanks to dubcat for his invaluable effort!

[dj_buckley]

Probably the reason I'm so confused

[dubcat]

Hey guys, been afk from the forums this week.

the point is to have a color managed workflow.

This pretty much answers all the questions.

is this correct?

Have you tried to render the material ? The material preview has some kind of bug, I reported it on mantis a week ago or so.
Add and Divide has to be done in linear.

It's so darn confusing

The original post is about calibrating you HDRis, so the brightest part of the sphere is the actual albedo color.

The texture splitting stuff is irrelevant to the original post, it's about taking control over the actual texture albedo.
I use it all the time for glossiness too, you keep all the details but you can change the glossiness value, so good.

[James Vella]

Ok Brilliant, so that must mean the last node (Dynamic Texture) is on Multiply mode - correct?

Thanks!

[dubcat]

Ahh sorry I didn't tag the last one. It's "Linear Light" :)

[joeperry54]

Thank you!

[amrelshipli]

Awesome ! u are genius ! can u upload the hdri plz ! i cannot find it anywhere plz !

[Xntric]

I'm in the process of making a shaderball scene for Lookdev.
And I want the scene to be lit up by HDRI.

I think that when you're creating and testing new shaders, it's important that you do it in a properly white balanced and colour-calibrated scene, or am I wrong?

I have followed the guide in this thread and adjusted the hdri to match 18% grey.

So far so good.
My question is, should I also use a colour checker and adjust the hdri to match that?
And if so, how would I do that?

[springate]

Does the Exposure Control rollout (shortcut 8) make any difference using this process? Should i set it at "no exposure control"?

[dubcat]

Awesome ! u are genius ! can u upload the hdri plz ! i cannot find it anywhere plz !

https://gumroad.com/jorgenhdri

My question is, should I also use a colour checker and adjust the hdri to match that?

You should use that HDRi as a HDRi. And then go into the Corona settings and switch from EV to Camera settings, and input the same ISO, Shutter and Aperture values you used when you captured one of you photos. Create a Linear profile for you Camera with 3DLUTCreator. Open your photo in Lightroom and apply the linear camera profile. Save it as sRGB 16 Tif, and open it in Photoshop. Recompile your HDRi with the linear tifs.. Sample a place in your linear photo, and adjust the values of your HDRi with a color correction to match this value, while you have the proper corona camera settings.

Does the Exposure Control rollout (shortcut 8) make any difference using this process? Should i set it at "no exposure control"?

I never use Physical Camera, because it gets affected by the tonemapper in "8". Use Corona Camera and its camera settings instead.

[cjwidd]

Firstly, thank you *so* much for this post, it is tremendously helpful. Second, in Corona version: 4 (DailyBuild Feb 18 2019) the color picker in the Corona Color texmap does not show options for sRGB, 0-255, 0-1, 0-100 are not visible.

- Has this [very useful] feature been removed or can it be enabled elsewhere in the UI?

You calibrated neutral gray as 18% linear/RGB, which is something like 117, 117, 117 sRGB.

- How does 128, 128, 128 compare to these values? Is 128, 128, 128 not a neutral grey?

Regarding ColorChecker Passport swatches. In the far right of the image (p.1), black is indicated as 3.1% linear/RGB. In another post I have seen black calibrated differently, e.g. "artistic" [30-240] sRGB; "strict" [50-240] sRGB.

- How does one make sense of these different interpretations in terms of best practices?

[romullus]

Firstly, thank you *so* much for this post, it is tremendously helpful. Second, in Corona version: 4 (DailyBuild Feb 18 2019) the color picker in the Corona Color texmap does not show options for sRGB, 0-255, 0-1, 0-100 are not visible.

- Has this [very useful] feature been removed or can it be enabled elsewhere in the UI?

No, it hasn't been removed, but you have to enabled it first. Go to customize>preferences>general and choose color selector -> Corona improved picker.

Regarding ColorChecker Passport swatches. In the far right of the image (p.1), black is indicated as 3.1% linear/RGB. In another post I have seen black calibrated differently, e.g. "artistic" [30-240] sRGB; "strict" [50-240] sRGB.


- How does one make sense of these different interpretations in terms of best practices

3.1% RGB <-> 8 8 8 RGB <-> 53 53 53 sRGB As you can see there isn't different interpretations here.

[cjwidd]

Ah, yes, the Corona Improved Picker makes interpreting the different values *much* easier, thank you for pointing that out.

You are correct, there is not a difference of interpretation, which I can see now thanks to the Corona Improved Picker.

My only other question pertains the sRGB 128, 128, 128 "grey". I had some naive opinion that sRGB 128, 128, 128 is somehow neutral grey, although I cannot account for where / how I acquired that opinion; perhaps because 128 is in between 0-255.

Nevertheless, the point is that sRGB 128, 128, 128 color is not of any particular import as it pertains to calibrating exposure, correct? I apologize if these questions are offensively basic, but I just want to be clear about the interpretation of RGB and sRGB going forward.