Hello again and welcome my UE5 series. This time I finally take a look at Lumen. Lumen is UE5’s new real-time global illumination system, that was created to give users the ability to have real-time lighting without having to worry about baking lights and similar things.
There are two main reasons I am interested in Lumen. The first one is that it’s a new tech and I think it can do a lot of great things for games. And the second, because one of the gameplay mechanics in Just Let Me Go is about turning lights on/off to avoid detection, and that means players will potentially be turning lights on and off a lot in the game. Since Lumen is real-time, I think using Lumen in Just Let Me Go would create a lot of nice lighting effects.
You can turn Lumen on by default when you enable Raytracing in the new project screen. If you turned an existing project, you can turn on Lumen manually by going to the Rendering settings and then selecting Lumen as the default GI method.
I had this scene that consists on one L-shaped hallway and two lights. When I turn on/off the lights, this is what I get (note that the girl keeps some light on her because her Blueprint has a “lighting rig” that projects light on her all the time, to get some “chiaroscuro effect” during low-light situations).
One thing I noticed during my tests is that “Use Hardware Ray Tracing when available” was turned off. I turned it on, expecting a better result, but this is what I got.
While I expected the hardware-accelerated GI to work better, it ended up being slower. One thing I don’t like, even from the first video, is how turning off the lights makes the GI gradually go away slowly. After tweaking some settings on the lights, I reached something that I like slightly better, but still not there yet.
I have to continue experimenting with Lumen a little more and find out the optimal settings for this, so I get the effect I want for the lightbulbs.