New Sky/Atmosphere model in 4.24

[Joaobrasil65]

I have a number of questions about the SunSky and the changes I have to make to use it. First, is there a technical guide on how to use it?

Second, my particles systems now are black. I had a blood spray emitter upon hit that was red, Now it is black…

thoughts?

@pf_breton

Hi,

I need to give you some background on this prior to answer individual points below.

The SunSky positionner is a plugin that was added in Unreal in 4.21. It lacked of proper shading technology (physical sky). In this release, this has been added to it in the form of extra components that can be used individually. The main use case is for Architecture where maintaining a notion of physically correct values for lighting, camera EVs and material parameters is a recommended practice.

From the comments i read below it seems that you are starting from a project template that isn’t right for that type of use case and hit all the roadblocks that are solved by the Architectural Visualization project templates. I’ll get to that below.

In project settings, enable the following options:

Enable Extend default luminance range in Auto Exposure = true
Apply Pre-Exposure before writing to scene color = true

That will allow lights to go from low to very high ranges.

The lower part of the sky hemisphere is usually done by an exponential height fog that should be added separately to the scene which isn’t part of the Sun Positioner plugin.

This is not the Hosek & Wilkie but still physical. Its using a derived version of the Bruneton sky which has several advantages over the Hosek & Wilkie. Its not something that was defined arbitrarily as you imply. The parameters are different (and more extensive) but it doesn’t means is physically incorrect because of that.

We have hidden the Sun Positionner plugin in Unreal by default but enabled it when using the project templates dedicated to Architectural Vis. However you don’t need to use that plugin to use the new Sky shader. Just add a Sky Atmosphere actor from the Visual Effects category and you have it.