Issue with VraySky and Exposure.

[KushKush]

I having a trouble to understand how Vray-sky works in terms of representing sun and its exposure(It has a huge bloom). I've added a reference and three screenshots, two of which shows my attempts to toggle vraysky and 1 shows vray bitmap hdri.
My question is, how should I set my settings so I can remove the huge bloom around the sun area but at the same time retain the same amount of sun intensity on the the scene?

Vray exposure is set to auto exposure, I've also tested with 14 EV.
Scene contains two light sources, Vray-sun and Vray-dome light with hdri.

Vray bitmap hdri with low highlight burn.
Upper arrow shows location of the sun in the scene and lower arrow shows were vray sky assumes the sun is. Highlight burn is at 50% to show reduced effect &l ocation of sun in vray sky.
100% highlight burn and the huge bloom I'm having issue with. Why is it so big? Is it really physically accurate?

https://www.youtube.com/watch?v=9UwO...nel=SoudaSouda - Reference, 0:59 frame shows my intended result. The sun has a look of lens effect added but its not ridiculously huge bloom.

[^Lele^]

Reduce the sun intensity, and you should be allright.
Without exposure, at the sun-height you show, a multiplier slightly above 0.01 ought to get you the results you're looking for.
To do so without changing scene properties, use one of the many possible environment overrides (render settings, materials, or render elements + compositing).

[KushKush]

Why is VraySky center of intensity starts at the horizon instead of at the location of the scene sun node? VraySky parameter called specify sun node is enabled.
By toggling "highlight burn" bar or rising/lowering "Sun intensity bar" it seems that VraySky's sun is slightly above horizon level instead on point of the sun. Why is that?

[^Lele^]

The locator is meant to give you an *angle*, as the sun is "infinitely" far out.
This means the height you're expecting is different from what you get (lower, in your case.) because the sun is *not* sitting where the sunlight gizmo is.
You just need to raise the sun a bit higher above the horizon, and you'll be fine.

As for physically accurate, particularly in that respect, it's as close as it gets.
I last captured sunset sequences for verification in 2015, and that effect was very clearly visible (see below).
It's of course dependent on the other parameters, like turbidity and haze (as in complete void there would be absolutely no halo, as light wouldn't scatter at all.).

[KushKush]

Excellent! Thanks for taking the time to explain to me the information. Have a great day Lele.

[piotrus3333]

I would like to add a bit about VRay sun on the desert - ground albedo and turbidity (only in Hosek et al. sky model).
grab the color of your desert and decide on turbidity. not an expert on deserts but I guess depending on the wind and type of desert it get enywhere within the range VRay supports: 2-10
aerial perspective with colour might be helpful as well.

edit: and use filmic tone mapper. the easiest way to see how it would look as a "photo shot on camera".

[piotrus3333]

and how the bloom size is in the lens effects settings:

[KushKush]

Thanks for explanation, I currently testing various hdri's, I'll keep turibidity tip in mind though.

[Joelaff]

Never saw the point of the whole "exposure" system. We always disabled it (Set a sun to about 0.03 for proper exposure starting point). I don't like having my exposure tied to my aperture and shutter speed/angle.

It just doesn't make sense in CG. I want to set the shutter speed/angle to a particular value and the aperture to a particular value without having to go around changing ASA/ISO, etc. I don't see any benefit at all from using it, and I come from a professional large format photography background, and understand all the exposure stuff like the back of my hand. But I guess some people do