Why are my Lumen lights still being calculated through walls/meshes - is there a way to stop this?

Hi all. I have a scene that is using Lumen, I have quite a few lights, but most lights (at any one time) are completely obscured, yet checking the GPU Profiler they are still being calculated…

Take this scene for example…


There are two lights in front of me, two lights behind, and perhaps one around the corner which attenuation radius’s may be in view of the camera.

Yet here is the GPU Profiler…


It is calculating lights that shouldn’t be affecting the scene - lights that are 3 floors away. Why is UE calculating these lights when there are several floors of mesh between the character and the light itself?

Here is a light complexity view of that part of my scene, where in my head, there’s only 3, maybe 4 lights that should be having an effect on the scene…

Am I thinking about lighting wrongly here? Or is there a setting that I have missed?

Any help would be greatly appreciated, I’m scratching my head.

Have you tried tweaking the draw distance

image

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Hey! Yeah I’ve got draw distances set up on all the lights, but this is horizontally. I’ve got this hotel, so let’s say I’m on floor 3, the lights directly below me on the ground floor are still being calculated. I’ve set the ground floors lights draw distance to be appropriate on that floor, to be visually acceptable when you walk around, but because I am “close” to them even though I’m three floors up they are still being calculated.

I guess this is normal behaviour? Can you have draw distances differently for horizontal and vertical?

Am I going to have to use trigger boxes to kill the lights?

Does that make any sense?

Sounds like it :slight_smile:

It’s not too bad though…

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Yeah I’ll give that a go, if I find an alternative more streamlined solution in the mean time I will update this thread. Cheers!

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You could have a box collision around the player, that only overlaps lights? And switch them on and off. Don’t even know if you can overlap lights… :slight_smile:

Or you could put the lights in blueprints and they trace once a second for the player, and turn themselves on and off.

Some ideas…