I just posted this issue ( Lumen surface cache scale woes ) but I wanted to provide some feedback here also regarding how finicky and difficult working with the surface cache is. A casual scan when I was researching this issue turned up problem after problem with people not being able to figure out why objects aren’t in their lumen scene when they ought to be.
The problem with a system that “just works” is when it doesn’t work, now you have two problems. Many projects require finer-grained control over lumen that just isn’t there. The reliance on screen traces obviously invalidates a number of requests to leave things out of lumen (since if they’re getting rendered at all they’d still be visible in screen traces), but the tendency of objects to randomly be excluded for unclear reasons is a real usability issue with projects that aren’t just third person character action titles.
If this thing is going to ship in every game going forward as the gold standard for UE lighting (which certainly seems to be the goal with performance improvements) I just feel like it’s going to need to be more reliable, or give us an actual API to interact with it.