Color temparatures, sky color, ect. and COLOR SPACE

[vlado]

Normally when you use the sun/sky and VRayIES lights, you should use a V-Ray physical camera with a "D65" white balance preset (otherwise the colors tend to be a little on the blueish side).

Best regards,
Vlado

[pailhead]

Vlado, are you aware that even if we do use that preset, our results will still be different?


LWF:

vraysky + vrayIES => vray physical cam => D65 wbp => one result

(lets say that this one looks correct)

vraysky + vrayIES => vray physical cam => neutral white => other result

(lets say that this one is a tad on the blueish side, since we didnt use a white balance preset)

No LWF (default

vraysky + vrayIES => vray physical cam => D65 wbp => yet another result

(this one is kinda saturated)

vraysky + vrayIES => vray physical cam => neutral white => something completely different

(this one is, like, BLUE, saturated would be a small word here)

[pailhead]

Normally when you use the sun/sky and VRayIES lights, you should use a V-Ray physical camera with a "D65" white balance preset (otherwise the colors tend to be a little on the blueish side).

Best regards,
Vlado

Also, what happens if we have a lot of objects, or walls and ceilings that are painted with warm colors, won't this make things even more... yellowy?

[vlado]

Well, this is as you wish, of course. Changing the white balance is more similar to adjusting light colors. Changing the materials, on the other hand, can change entirely the way light is distributed in the scene (since light bounces will be different).

So, if your material is grey and want it to look grey when using IES lights, you should adjust the camera white balance or the light color, rather than correcting the material itself.

As for the whole LWF thing, I don't really like to give any advice on that (other than it's just a way to view the same image - there is no really correct and incorrect here). I do have my opinion on this, but since it is different than most people will tell you, it may only confuse you further.

Best regards,
Vlado

[vlado]

Vlado, are you aware that even if we do use that preset, our results will still be different?

That's the whole point, isn't it? If using gamma or not using it gave you the same image, it would not make much sense.

However, if you would like to get gamma correction while keeping the color saturation the same, you can always use the "Intensity gamma" color mapping mode, instead of the actual gamma setting.

Best regards,
Vlado

[pailhead]

So, if your material is grey and want it to look grey when using IES lights, you should adjust the camera white balance or the light color, rather than correcting the material itself.

Right, but the relation between my grey, and vraySKY is different when working with LWF than without it.

Without it i have a very saturated sky working against my gray material, and even d65 may not be enough to desaturate it.

With it, i have a pale blue sky working against gray, which can probably be corrected with d65.



Where i'm not clear is, what if i have a really large room, like a theater, with one side being illuminated by orange (3000K) lights, and the other by cold blue lights (8000K). Since they are only wallwashers, they don't really meet and contribute to the overall illumination of the space (lets even say that it's dark, because there's a play on).

If i use d65 to compensate for the oversaturated 8000K, then my 3000K lights will be even more saturated.




Note that i've changed my stance on this. I no longer thing that i have a problem when using LWF, everything actually seems much better with it, but on default, everything is too saturated.

[pailhead]

I don't think we should throw in the towel quite yet.

I also think something is wrong.

In my LWF tests the sky looks far too pale.

The way i understand, this is actually correct, it was too saturated without LWF.

But hey, i have the feeling that i'm leading a crusade here all by myself

[JeffG2]

As for the whole LWF thing, I don't really like to give any advice on that (other than it's just a way to view the same image - there is no really correct and incorrect here). I do have my opinion on this, but since it is different than most people will tell you, it may only confuse you further.

I'm up for a little confusion!

I'd greatly value hearing your opinion.

[pailhead]

Same here. The only thing that i wont settle with is the white balance thing, because it happens after this whole mess (lwf, no lwf, or any other type of color mapping) am i right?

[vlado]

Same here. The only thing that i wont settle with is the white balance thing, because it happens after this whole mess (lwf, no lwf, or any other type of color mapping) am i right?

No, actually the white balance happens *before* the gamma correction and other color transformations.

Best regards,
Vlado

[pailhead]

I give up. I'll stick to the 2.2 gamma thingie

[pailhead]

Vlado, one more question though?

when we apply a d65 white balance preset, is the math behind it like this:

X (pixel value) +/* (whatever the function is) D65 preset = X*D65?

Then if we use LWF, will it be something like

LWF*X * d65?


I know that the way i put it it looks silly, but i hope it can be understood.

[vlado]

It works like this: first the original color is taken, then the white balance is applied, and finally the gamma correction.

Best regards,
Vlado

[pailhead]

Is the original color different in most cases when people work with gamma correction?

(ie. when we linearize our textures)

When i look at an image that was rendered without LWF i see certain colors, like 128,128,128 grey. When i prepare the same scene for LWF 128.128.128 grey in a texture will be shown a little bit darker. If i tick the sRGB button, it will be brighter, the way i expect it to be, so the base colors are actually different?