Downloaded the UE5 EA this evening as I’m excited to play with the new features. I’ve been working on various projects using raytracing lately and converted some of my projects over to UE5 and switched from RT to Lumen.
Is it expected that Lumen should have worse performance than raytracing? Examples are
Archviz style room:
RT: ~60fps, Lumen: ~45fps
Stylised village scene:
RT: ~47-50fps, Lumen: ~20-25fps
This is on a 3090 RTX and feels relatively low, though I have no idea what my expectations should be.
I had a play with some Lumen settings and also noticed Use Hardware Ray Tracing when available seems to make no difference to the framerate/time. Is there a way to confirm that Lumen is using hardware raytracing on my system? Is the option just not working/hooked up to the backend at the moment?
Any advice on Lumen performance, what to expect and how to optimise (other than what’s in the documentation - already scanned through that) would be great.
That was my expectation (and I thought the point in Lumen) - that Lumen would be expensive, but not as bad as rtgi. Tried a few more projects now though and definitely getting longer frame times and lower fps when using Lumen.
I’m wondering if something’s not quite working right in EA with my card or Nvidia drivers. Mainly because turning hardware RT Lumen support on and off doesn’t affect framerate or draw time at all.
Having another read of the documentation about Lumen, it’s not really clear if hardware RT is used for everything when capable hardware is found, or just for things that need it (ie. skeletal or morphing meshes). I wonder if that could explain the lower fps in Lumen than RTGI with my 3090 if Lumen is software RTing the distance field meshes still.
Yes. RT reflections and GI look better that Lumen. Besides that Lumen is kind of mixture of screen space / world space techniques and because of that you get all those related limitations and glitches. But… even with all that Lumen is way better than anything (except proper RT) that other engines have to offer. Lumen is kind of like SVOGI (Cryengine 5) on steroids.
That depends of what you do with UE4/5. I’m not a game developer and I couldn’t care less about 4k, 60 fps and other similar things. So, in my case possible low performance is not an issue. I’ll take 10 frames per second in UE4/5 over 10 second per frame in offline renderers any day.