Skylight, Environnment color and Brightness


I’m looking today inside the samples to understand a bit the new lighting system (with the updated version of lightmass). In UDK, when we wanted to setup a lighting for an open environment, two important settings where needed : the environment color properties in the wold properties and the color and brightness of the Dominant Directionnal light.

In UE4, this changed a bit and I’m confused. First, it looks like you have to push way more the brightness of the lights (such as the such) to simulate a similar lighting. For what reason ? Is this to give a better control to the lighting in general ? (Like : instead of small decimal values for small and precise lights we use direct integer now.)

The environment color setting inside WorldSetting > Lightmass seems to be enough for the static environment and the skeletal meshes. However any interp actor get a much more dark shadowing color. Which put them outside of the lighting and make them visually obvious.

What is the purpose of the Skylight settings ? The Lightmass documentation talks about the old skylight actor which is obviously not related to these new Worldsetting properties. Also, some projects have these settings enabled (with very small brightness value) while some other don’t and have totally disabled it. Why ?

There is also global illumination settings in post process that enables you to tweak the intensity and color.

I think the proper way to go for setting up exterior lighting in Rocket is now to use the Ambient Cubemap located in your post process actor settings. It kind of acts like an IBL ambient on your geometry from what I saw and gives pretty nice results.
Not sure how it interacts with Lightmass though, if it applies the ambient pass uniformly on the whole level or if it takes into account the lighting from the dominant light.

I guess yeah, even if I think it’s weird to have this cubemap setting inside the postprocess volume. Since almost none of the samples are using this setting (I didn’t check every one of them, but the Shooter game don’t and the Realistic Rendering neither) it would be nice to know a bit more about this.

By the way, the Lightmass documentation has been a bit updated regarding its UE3 version, but I believe there is still some changes to be done