UE 5.1 lumen light leaks

Hello, I have interior/exterior architectural scene, as start I used blank template. For the lighting there is sunsky default template system only. Is there way to get rid of these leaks, or it is the cost of the lumen engine? Many thanks, Filip




Show a viewport visualization of the global distance field. You’ve probably overstretched the meshes that you’re using to build the scene. If it’s not that, then the meshes are too thin or the DF resolution isn’t high enough. There are some other things that can factor into the mix too, but I’d rule those out first.

Thanks for the reply! The leaking/bleeding appears and disappers as camera moves. When I set the indirect lighting intensity to 0 it fades away - so I think it is related to “directional light” indirect lighting. When I decrease in the static mesh build parameter the max lumen mesh cards to 1 it disappears (does not work with all problematic objects). Increasing the distance field voxel density in project settings to max value 0.4 does not help. Increasing the mesh build settings distance field resolution scale to max 100 does not help. Tried to collapse the shelf to individual box objects without success. Do you have any clue please?

the screenshots below are from new simplified scene, where the problem persists:




This is curious, very curious. I might ask you to get a screenshot of the surface cache coverage visualization, but I think I have a guess as to what’s happening. It appears you’re getting leaking from the low-res distance field represenation, what I might suggest is to check your project settings and turn on ‘detail tracing’, which will make rays near the camera actually respect the higher-resolution distance fields.

Beyond that, by disabling the cards, you’re effectively stopping light from bouncing through your scene at all, which is solving your leaking problem but also stopping global illumination from bouncing outside of screen-space. That’d be why your lighting is changing as the camera moves, as the screen-space representation would be losing details and picking up on others as your position changes.

Unfortunately, even with all of the improvements lumen received in 5.1, it still cannot handle high-quality indoor lighting without hardware ray-tracing it appears.

Thanks!

detail tracing was checked already. The glittering problem was there already when the cards were on the default value of 12. The secondary bounces are just sort of glittering as I am moving around. I tried even to change the material to basic, happens in entire scene in some places and looks almos like some postproduction effect. Checked some tutorials on more detailed interiors and never seen this issue.
here is the vizualization:

even I more simplified the scene, the problem is same, leaks visible from the outside:

just realized when I change the shadow map method to non-beta the problem is solved, but as a noob, not sure yet what other good stuff I am loosing with this change:


and now realized there were shadow maps on the template light I changed to raytraced and all is ok. Is it good idea to use rt shadows for this case in UE? Stupid question I know, but I dont have much experience vith realtime…

Unreal engine is an incredibly complex piece of technology, and the learning curve is steep and inconsistant. While the path-tracer handles relatively similarly to other offline renderers, many other features don’t behave intuitively to people who don’t know games.

By non-beta shadowmaps, what do you mean?

Also, is definitely a good idea to use RT shadowmaps for archvis, not a stupid question though as their behavior isn’t incredibly intuitive. It’s the highest quality shadowing solution, but it also has limitations such as not shadowing volumetric fog quite yet.

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Hi jblackwell and thanks for the reply!
With the non beta I meant project setting>shadow map method>virtual shadow maps (beta), but now with “RT shadows on” all works with the beta as well. Turning the RT shadows on was the solution - simple, but as always when you learn something that took me almost whole day to figure it out;) Yep UE is great, but not easy to learn…:wink:

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