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Volumetric Lightmap Samples bug (Reproduce-able)

So I think I've discovered a rather large bug with volumetric lightmaps in that it's creating a lot of unnecessary samples and ignoring the height of the Lightmass importance volume:


So here's my test scene; just a simple landscape mesh, a skylight and directional light, all set to static.

Here is the scene post light bake:


Note the lightmass importance volume and how far off samples are generated up in the Z direction. I can understand some extra samples are necessary for 'padding' with this system, however this seems excessive. The result of this is VASTLY increased bake times compared to Sparse Volume Lighting Samples.

For example; on a larger scene my bake time went from 20 mins with Sparse Volume Lighting Samples, to 12 hours with Volumetric Lightmaps!

I'm thinking this must be a bug??

Other than this I've been loving the new lightmaps so far and hope to use it but this is killing my bake times and most likely eating up a lot more memory!

Link to forum discussion: https://forums.unrealengine.com/development-discussion/rendering/1394082-volumetric-lightmap-samples-bug

Product Version: UE 4.18
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asked Dec 01 '17 at 03:20 AM in Rendering

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avatar image Priareos Apr 27 '18 at 11:25 AM

I'm having the exact same issue, did you find a solution to this?

avatar image HappyEngine May 08 '18 at 05:44 PM

same, i dont remember this happening befor

avatar image KTR19 Jun 06 '18 at 11:42 PM

Same here, I ended up maxing out the CPU cores in the options for the Swarm Agent for baking, it significantly reduced the time to Cook the lighting but made the system almost non-responsive till the Bake was complete.

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