Sky atmosphere day night cycle ?

The new sky atmosphere will be completely dark when the sun go down, but i saw some guy in youtu use skyatmosphere can make a good transition from day and night, and their night is not dark ,how to do that?

You can have 2 directional lights with sky atmosphere - but you still need to adjust intensity.
There is a setting on the directional light that defines if its day 1, or night 2.

Thanks ! I try and i work .But Now I face a other probem. I Roate The Moon DIrectrion Lgiht As Opposite Direction Of Sun Light. When Sun And Night Toward Horziontal, Sky Will Be Complete Dark At That Moment . When I Just Change The Light Value It’s Has A Lot Limit To Make A Sytlized Sky.
And I Saw The Talk Of Unreal How To Build Fortnite Sky . Which They Use Different Sky Atmosphere Value , And They Do a Very Good Transtion . Any Idea?

Here is the Talk : 27:00 - 28:00

You need to code a separate blueprint that reads off the angle of the sun / or the time of day - and adjusts all the different parts accordingly.

In a Default setup you need to manage
Skylight intensity
direction light (1 and 2) plus rotation.
volumetric fog
post process (eye adaptation)
and skyathmosphere rie and mie scattering values.

It gets quite complex.

Assuming you are using physically based lighting then literally the only thing you have to do is add a star HDRI to a skydome material

Guys, Thank you angin ! As you say , make a stylized look phiscal sky need to change a lot value , our artist say that so complex and not intuition.
HDRI skydome material cause less control of day night cycle.
I’ll post somehing on ths thead when i have some good Found.

Thank you angin.

Why would using an HDRI give you less control of the day/night cycle?

Because i want a procedural parameter to control the sky as much as possible. Static hdri have some advantage and disadvantage.

Advantage: very hight quality and fully control.
Disadvantage: not dynamic change. Since i use physical bae sky but want to get stylish result. So i won’t use it as physical correct way.But as you know ,physical sky has a lot value need to setup careful.

if you had played genshin impact, their night sky milky way is completely dynamic. but red death redemption 2 look like use static image to make milky wal but remain some atmosphere scattering at night to make night brighten.

So i think it’s a trade-off.

You can make the material as complex and dynamic as you want. You can layer as many effects (including masks and other cubemaps) as you want for parametric control.

The main point I was making though is that you just need something in the material. Anything really as long as it isn’t black. An HDRI works, but it could be just a solid color if you wanted or any number of other things.

The the reason the environment is black at night is because there’s nothing in the sky material, since there’s nothing in the sky material the skylight has nothing to capture. Since the skylight isn’t capturing anything, it doesn’t cast any light and thus the terrain is black.

If you put anything in the skydome material that isn’t black, it will give the skylight something to capture and that will be used to light the terrain. Assuming you are using a physically based lighting setup then you don’t even usually have to do anything to handle the transition, the SkyAtmosphere and auto-exposure will adjust and clip the night sky out.

tl;dr: My advice is you focus on making a proper skydome material (even without an HDRI), fussing with the SkyAtmosphere actor settings isn’t a good approach for a night sky.

Yes ,you’re right .

For technical side, I’am wondering how fortine use skyatmosphere to achieve stylish result. Did they change some engine c++ code stuff or just use the offical version ?.
Just change sky not the enviorment. Enviorment setup of sky and terrain stuff can be spearate .
I had spend a few day to find a way to do this but no luck。