Physical Sun and Sky vs. Constant Material [solved]

[artmanphil]

Howdy folks,

any idea why when initializing the Physical Sun and Sky (SI2011SP1) all constant materials in my scene get black? Mit simple setup is seen on the screenshot. If not compatible, how do I create a proper brightener/reflector then?

Hugs
Phil

EDIT: Works! Push up the Incandescence of the constant material to like 100000 and it gets white. DAFUQ???

[Rork]

Sun & Sky follow the 'linear rules', as the old shaders like Phong, Lambert, Constant etc. don't.
Especially the Constant shows this. You always have to crank up the RGB values way way up there to see something.
It's the same with lights, they behave differently (need higher values too) when working in linear space.

Moral of this story, use the architectural shader, or another renderer..... ;-)

rob

[artmanphil]

The Architectural for Reflectors for glowing surfaces?

[Rork]

What I mean is that the architectural shaders work in combination with the Sun&Sky/Linear system.

All the other so called 'legacy' shaders will give you issues when working in a linear fashion,as they were never designed to do so.
All of these shaders use 'hacks' to render a certain effect. E.g. a light's highlight which is basically a reflection of a bright area.
All the so called 'physical plausible' shaders behave like this.

So.. yes, try to use the architectural shaders as much as possible, and be aware of issues when using the 'legacy' shaders.

Hope that makes it more clear.

I advise you to read up on the while linear workflow, and have a look what's happening under the hood when using the Sun&Sky/tonemap system.

Recently there was a similar post, so follow my bloglink to some notes on this, and have a look at Kobayashi's blog as well: http://kobayashystips.blogspot.com/


rob

[Maximus]

When you go to Edit>Initialize sky shader this ppg will pop up:



Uncheck that "Use Exposure shader on lens" and add it manually from pass options lens shader.
Why is that? Because if you leave it on it will create a sky+sun+photo exposure lens with all parameters linked to cm^2 factor at 1.
While this is (pseudo) correct way of use it will alter all the other shaders and lights in the scene.
Reason why you dont see your constant is because in your photoexposure the cm^2 factor is at 1. So you have to crank it up at insane number to see your constant.

Hence to me it has no sense to use cm^2 factor at 1. Add manually a photo exposure with cm^2 factor at 10000 and you'll be fine.

[Rork]

Yes, that too ;)

Thanks Max for chiming in on this one.

[Kzin]

When you go to Edit>Initialize sky shader this ppg will pop up:



Uncheck that "Use Exposure shader on lens" and add it manually from pass options lens shader.
Why is that? Because if you leave it on it will create a sky+sun+photo exposure lens with all parameters linked to cm^2 factor at 1.
While this is (pseudo) correct way of use it will alter all the other shaders and lights in the scene.
Reason why you dont see your constant is because in your photoexposure the cm^2 factor is at 1. So you have to crank it up at insane number to see your constant.

Hence to me it has no sense to use cm^2 factor at 1. Add manually a photo exposure with cm^2 factor at 10000 and you'll be fine.

yep, 10000 ist the default value. it should also applied to mia_photometric_light for example, same problem here with 1 as default value for cm^2.

cm^2 at 1 makes sense because its the realistic value. the problem is you cant see anything then white with 1 because the rendering is not tonmapped like our eyes would do it. because of that, you need the photographic exposure shader. when you use 1 for cm^2 then also use 1 for rgb unit conversion in physical sky shader.

[artmanphil]

Thank you!