Ultra Dynamic Sky

A small update to UDS just went up. Just one change. It fixes a bug with volumetric fog, so if you’ve been having problems with that, be sure to grab this update.

The changelog:

  • Fixed a bug which could cause flickering and breaking of volumetric fog. This involved adding a specific “cast shadows” option for the sun and the moon, in their respective categories. It’s enabled for both by default.

As always, you can check the changelogs here:

Are there any specific default configuration settings, is auto exposure a requirement now? With the latest update, and previous versions the default settings, using the inbuild lights, result in the scene to be too dark. I played around with sun intensity, brightness settings, and the post process, with auto exposure enabled/disabled, but it always remains underlit.

The image is 1200 o’clock, with defaults, using only a slight LUT post process.

The result can be managed with: Sun Light Intensity = 8, Night Breightness = 70, Overall Intensity = 5.

Auto-exposure isn’t a requirement, no. There’s no reason setting the exposure manually shouldn’t work.

There were changes a few updates ago to address problems with default brightness, but specifically because it was looking too bright and washed out for some. The current version was set up so that it looks relatively balanced without any auto-exposure by default.

For reference, here’s how that looks on my end, in the current version. Empty scene, no auto-exposure, and sky using default settings:

I’m not sure what’s causing your project to dim everything down so extremely. The values you mentioned for things like Night Brightness and Overall Intensity are definitely way higher than they should ever need to be. If you try the demo map included in the UDS files, does it exhibit the same problem? Also, are you using any particular unconventional lighting features in your project? And is ray tracing enabled?

Having great results with your pack, I’m leaving advanced settings alone and manipulating the rest with data tables and there’s a lot of flexibility.

Looks like you’ve enabled Extended Luminance in your project settings. UDS currently uses default lighting values which are much darker than real-world ones.

Ray tracing made no difference, disabling the UDS feature ‘Use Exposure Range’, is a workaround.

Thank you, this was indeed the issue! Disabling it yield now the desired effects.

Not a huge issue but if I play in editor and the player spawns considerably from the default start location the sky is just blue. Visible in this screenshot Not tested yet if this also happens in some circumstances in a packaged export.

Any tutorial or idea on how to set up lighting for accessible houses and buildings on the map?
Every way I do it is with the strange lighting along with the UDS during the day and night transition.

Maybe I am missing something obvious but I am really struggling to control the depth fog/heighfog on the horizon. I am doing a sunset sky and no matter what I do there is a thick band of brown coloured fog on the horizon. I want the fog on the horizon but I want to change the colour. Most likely it will need to be a physically innaccurate colour but no matter I can’t really understand what parameters I can control affect that fog colour on the horizon (I tried adjusting the mie scattering and rayleigh scattering to no avail). If I go into the height fog component I can see the brown colour coming from the fog inscattering color. If I try and force a change to that colour then the fog goes to the colour I want but immediately reverts back because it’s being controlled in the shader by other parameters. Do you have any advice for adjusting this height fog inscattering colour? Everything else in my sky is perfect… just not the height fog colour.

I thought I figured it out by creating a custom height fog actor and using that instead. This worked but again the colour gets reset by UDSky even with the custom actor. I can turn off use sky atmosphere but then I lose all the other cool sky atmo effects

If you set the UDS Skylight to movable it brightens interiors a lot.

Are there plans to optimize mesh?
Its size, triangles…

Hi guys, any idea how to improve this view (sun reflection visible on surface during clouded sky.

New update for UDS today. It’s 4.25 compatible and comes with a bunch of updates and refinements for 4.24 and 4.25. Some signifigant changes to fog and sky lights in particular.


  • Reworked Height Fog integration. When using sky atmosphere, the height fog now uses more appropriate color curves to determine inscattering color and directional inscattering color, with those curves tuned to align well with the default look of the sky.
  • Added a Height Fog section, with variables for the curves it uses to determine color.
  • Added an option to use a curve to change fog density throughout the day. The feature is disabled by default, and the curve provided is a flat value, meant to be edited to fit the user’s preference.
  • Revamped the Sky Light integration. The default is now a much improved version of the old “Fast Skylight” option, now labeled as “Cubemap With Dynamic Color Tinting”. A capture based sky light (the old default) is still accessible by changing Sky Light Mode to capture based. I’ve also added a simple option to use a static custom cubemap texture.
  • Added Sunrise and Sunset event dispatchers, controlled similarly to the existing Start Rain and Stop Rain ones. Useful for controlling lights or ambient sound. The specific times that these events are fired can be set in the Animate Time of Day category.
  • Reworked the sun so it’s scale independent. The default size of the sun is around the same, but Sun Radius values now scale differently.
  • Added a Cloud Sharpness variable. Increasing this gives the clouds exxagerated hard edges and can give the sky a somewhat stylized look.
  • Changed the default exposure range, to compensate for changes to auto-exposure made in 4.25.
  • Added settings for Night Sky Glow and its associated color. Basically a soft unform glow that fills the sky at night. Previously this was connected to the starlight intensity and not easily editable. Now it’s its own effect.
  • Made a change to how sky atmosphere colors clouds, to make them more scale independent.
  • Optimized the sky sphere mesh, particularly to use less geometry on the bottom half where the UV resolution isn’t needed.
  • Fixed the implementation of Night Brightness, which wasn’t working as intended when using Sky Atmosphere.
  • Edited the sky material to properly mask out all of the clouds, stars, moon, ect on the bottom half of the sky sphere.
  • Improved the way Moon Phase affects the strength of moon lighting and colors.

Definitely check out the new update for improvements to fog. The ugly sunset coloring has been improved and it should be easier for the user to make their own changes to fog colors throughout the day now.

Some density is needed because of how the shader utilizes UVs, but triangle count has been dramatically improved in this update. It’s down from 16k to about 5k.

I would recommend adjusting cloud shadow intensity so that it fully shadows the sun when obscured by cloud. I do really want to improve the way overcast skies look and behave with lighting though. That’s definitely going to be something I target in the next update.

Thanks for the new update, so far looks good! I think for the Ocean reflections I could use a dispatcher, hook it into the Ocean BP, then from there switch the Ocean material (to one without reflections)?

Another new update today, for 4.24 and 4.25. Wasn’t planning on updating again so quickly, but when testing for that last update I missed a serious bug in 4.25 to do with cloud coloring. So that’s fixed, and there are a handful of new changes I’ve been working on as well.


  • Fixed bug with cloud coloring at sunset, affecting 4.25.
  • Added variable to Cloud settings to adjust cloud shadow softness.
  • Added variables to adjust cloud shadow intensity and softness with cloud density, so the lighting can appear correct when the sky goes overcast.
  • Added a variable to adjust the amount of the swirling clouds texture which appears at high cloud density. Also adjusted the default value to be more subtle.
  • Changed blueprint/variable settings to work with network replication.
  • Added control of mie anisotropy based on cloud density, so that sunlight appears to scatter properly when overcast.
  • Added a “Soften Clouds” option. Erodes and softens the edges of the clouds, to make a more wispy, hazy appearance.

I’d recommend checking out this new update. I’ve done some things to improve the way lighting looks when overcast. I think it should solve that problem of the incorrect reflections.

I have not tested this a lot but has anyone else noticed too bright indoor environments with the latest update?

With the latest updates, the skylight integration got a major overhaul, so I’d recommend taking a close look at the new sky light section if ambient light (either indoor or outdoor) is looking too bright now. One of the changes is that the UDS bp takes control of sky light intensity with a variable, whereas before it didn’t touch intensity. And the default is no longer a capture based sky light. So definitely reassess the settings in that section if you’re bringing your project forward from an older version of UDS.

What do I miss if my scene is too light at night? UDS changing to night correctly but my landscape remains light. I tried use built-in, own sun actor, atmosphere on/off, lowering skylight intensity, but none helped. Im using World Composition and 4.24.

Some rooms are too bright, like some mesh materials let more light through.