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Point light with small radius missing from light bake

I've run into an issue where I'm trying to bake a series of stationary point lights. They all have a pretty small attenuation radius - somewhere around 100 units. Before building lighting, everything looks correct. However, after building, the light won't affect certain areas. For example, the ground will be lit, but not a tree coming out of the ground, or vice versa.

Increasing the attenuation radius of the point light seems to address the issue, but I'd ideally like to be able to keep the radii small, so that I do not run into the "only 4 overlapping stationary lights" issue.

Speaking of which, I have verified that this is NOT a result of the fact that only 4 stationary lights can overlap. The issue is present when building a single light with a small radius.

Thanks in advance!

Product Version: UE 4.10
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asked Jan 14 '16 at 12:28 AM in Rendering

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The sphere that you see is the edge of the lights fall off = no light. Turn every single light you ever make into static.(Too bad it isn't the default) You only need one or two lights to be set otherwise for objects that move. The tree could have a light map issue or the wrong uv set for the light map hard to know with the info provided. The ground is it BSP = unreliable/ hard to control if it's part of a Boolean.

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answered Jan 14 '16 at 12:54 AM

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avatar image thebarryman Jan 14 '16 at 01:18 AM

Hi Umberto,

These lights all have light functions attached so they need to be stationary, rather than static.

The ground plane is a static mesh, one included in the Unreal starter content I believe. This happens with all kinds of meshes so I don't believe it's a lightmap UV issue.

The radius is large enough to cast light onto the object -- it looks correct before building, it just breaks when you build it.

avatar image Tim Hobson ♦♦ STAFF Jan 21 '16 at 08:20 PM

Hi thebarryman,

Umberto is right on this with the lights radius, Lighting will not be visible outside of this area. If you're concerned about overlapping Stationary Lighting you only need to worry if more than 4 lights are overlapping with their radius, not for the entire scene. So if you're keeping the lights small enough you can increase the radius so without a problem most likely.

For instance, if you have 8 stationary lights in your scene lined up, you can overlap more than 4 of them they will not cause the stationary overlap issue.

Depending on the assets lightmap that the light is being cast on you may just need to up the lightmap resolution for better results.

If you're still having issues it may be helpful to post a screen shot of the before/after of your scene.

Thank you!


avatar image thebarryman Jan 21 '16 at 09:16 PM

The area in question is within the light attenuation radius.

The issue is related to attenuation radius, but not in a logical or "correct" way. There seems to be a magical threshold beyond which the light shows up. However, it is not related to the question of whether or not light "should" be cast onto the object -- it definitely should be, given that the object lies within the light attenuation radius.

As I stated in my original post, stationary light overlap is not the issue.

avatar image Tim Hobson ♦♦ STAFF Jan 22 '16 at 02:07 AM

Can you post a screen shot? At this point that may be more helpful than trying to describe the problem.

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