VRaySun brightness in VRaySky

[Morne]

I want to change the size of my sun, however when I do, I loose the brightness of the sun in the sky (not where it shines on objects)

For example with a low sun and size of 1, I measure the sun at about float 10. When I increase the size to 2, the brightness drops to about 2.3. Is this a bug, or expected behaviour?

Only workaround I can think of is to have 2 suns, one for the sky and the other that will actually illuminate my scene.

[tashko.zashev]

Hi Morné,
I think this was made to keep the overall illumination strength while adjusting the size the visible sun disk and shadow softness.

[Morne]

OK thanks Tashko, I'll cheat it with 2 suns then

[Morne]

Arrrrgggghhh nuts. 2 suns doesn't work because it creates another problem.

If I increase the sun intensity, it obviously also increases the illumination. Would be nice if can keep the sky correct, but cheat the sun in the sky. Will add it to the wishlist section...

[^Lele^]

could you not use the diffuse/spec multipliers in the sun?

[Morne]

could you not use the diffuse/spec multipliers in the sun?

No I've tried that. I've set diffuse contribution to 1000, but the sun in the sky looks the same, whereas the objects being lit looks nuclear. It also increases noise

[^Lele^]

i meant the other way around: raise sun intensity along with size, correspondingly lower its contribution. The sky may blow a bit, though, when directly seen (easy to rerender it alone and comp in.).

[Morne]

Yes but that again defeats the purpose. Even if I then render the sky seperate, how do I prevent the sky from blowing out, while getting the sun to look bigger and brighter. It's a very late afternoon shot and the sky is a big part of the render

[^Lele^]

the only way i can think of, is to use the sun and sky as normal, without visible sun disk, and then fake the disk with a self-illuminating geo, its shader within a wrapperMtl so that it doesn't contribute to any lighting.

[^Lele^]

I mean, in the physical world, the sun disk doesn't change SIZE, but rather APPARENT size, due to scatter (and hence also some energy loss) in the atmosphere.
So, to be physically accurate, not only should the sun brightness decrease as the area increases (same energy, bigger spread, less punctual intensity.), but it also ought to lose some energy to the atmospheric scatter (you'd see the sun disk bigger behind humidity: clouds, dense heathazes, and so on.).
I think faking it is best, yes... :P

[mitviz]

or just use a hdri

[Morne]

I mean, in the physical world, the sun disk doesn't change SIZE, but rather APPARENT size, due to scatter (and hence also some energy loss) in the atmosphere.
So, to be physically accurate, not only should the sun brightness decrease as the area increases (same energy, bigger spread, less punctual intensity.), but it also ought to lose some energy to the atmospheric scatter (you'd see the sun disk bigger behind humidity: clouds, dense heathazes, and so on.).
I think faking it is best, yes... :P

Jip, trying to fake it because the VRaySun has minimal settings for the haze, humidity etc :- )

or just use a hdri

Actually, this topic is just a part of it and I'm already blending the VRaySky with an HDRI but need some more "cheat" settings :- )