MegaLights in UE 5.5 – An Incredible Lighting Design Boost

I installed the UE 5.5 preview version and created a new scene. I then migrated the geometry from the virtual set I designed for CNA, earlier this year. I chose to use this project because it is based on an architectural interior and needs to use an architectural lighting design for it’s baseline lighting. That kind of lighting requires hundreds of lights to be added, in quantities that would crush performance. To achieve the lighting style and performance required for CNA, we had prepared the scene in UE 5.2 and used static lights, combined with light builds i.e. baked lighting. We couldn’t use Lumen, or any features associated with Lumen for the CNA project, as we couldn’t have achieved realtime performance – If a virtual set can’t run in realtime, it doesn’t work and is a failure.

With the original geometry for CNA now in UE 5.5, I enabled Lumen and MegaLights, and then began rebuilding the entire lighting setup from scratch. I didn’t create an exact facsimile of the original lighting, but after 240 lights, had a result I was happy would provide a representative test. Each of those lights was set to be moveable, and shadow casting. With MegaLights disabled in the scene, performance was a sluggish and unnacceptable 24fps. With MegaLights enabled, it jumped to an astounding 85-90 fps!

I didn’t delve into any of the settings, or attempt any form of optimisation. This was a previous scene, brought into the latest version of Unreal Engine, and all lights were added from within UE 5.5. The results are visually incredible, but the performance boost is astonishing. New versions of Unreal have often promised performance enhancements, but ended up disappointing by running more slowly than their predecessors. UE 5.5 with Mega Lights however, revolutionises real time lighting in ways I thought we’d only be able to expect from the development of new and insanely powerful graphics cards. This development is incredibly significant for designers like me, as it allows us to focus on the visual affects of each added light, without that sense of dread and resentment that came from watching performance die.

Will we still need to mindful of how we apply lights to a scene? Of course, but there is now a sense of release from the tyranny of the GPU Visualiser and framerates. For the BBC Paris virtual set scene, I worked on new techniques for lighting a complex scene in order to hit satisfactory performance levels whilst using Lumen. The whole night scene required only 5 light actors in the end, the remaining illumination coming from emissive materials. I can still utilise this approach as a component in many scenarios, but MegaLights introduces a whole new suite of looks to the lighting palette; scallops, ies profiles, defined shadows, focused lighting.

I am looking forward to reaping the benefits of using UE 5.5 and MegaLights on a live project!

References:

The MegaLights Demo from Unreal Fest Seattle 2024