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Light Source not effecting certain static mesh?

Hi guys, I can't seem to understand what is going wrong here. I have three rocks meshes, my lamp mesh, and the floor mesh in the image you can see that the light is showing up on the rocks and lamp but not on the floor. Very odd, I can;t seem to work out what it is causing this issue. Can anyone elaborate on what I might be doing wrong here?


I've just started a new project then imported my floor mesh and one rock mesh then put a light source in and it created the same results, so I'm assuming this means that there is nothing wrong with the settings but is the mesh it's self. I created this with blender so if anyone out there has had a simpler issue can could post there findings that would be great.

UPDATE -2: I think the issue is a lightmap issue as in the comments of (freckxnet)'s answer I mentioned about a basic cube I created without a lightmap then imported that and got the same results, then added a lightmap to it and sure enough the light began emmitting onto it. So after these findings I thought I would post my .blend file of my landscape in case anyone wanted to take a deeper look into what might be the issue. Also in (freckxnet)'s answer I've added a example of the lightmap that i'm currently using.

Thanks, Matt.

Product Version: UE 4.14
example.png (580.2 kB)
landscape.zip (138.1 kB)
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asked Dec 14 '16 at 12:48 AM in Using UE4

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avatar image CosmicMonkey Dec 14 '16 at 03:19 PM

I've added two more examples one before the light was rebuilt and one after. alt text alt text

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does the floor has lightmap uvs?

Light build creates lightmaps which are based on the lightmap uvs (uv channel 1). I don't know if UE creates a light uv channel on its own.


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answered Dec 14 '16 at 04:17 PM

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avatar image CosmicMonkey Dec 14 '16 at 05:14 PM

Hi thanks for answering, unfortunately I do have a lightmap on the floor it looks like the image. However, I do think this is the issue as I created a basic cube with no lightmap and imported and got the exact same results. Then gave the cube a lightmap and sure enough the cube had the light emitting onto it. I'll edit my question and post the source file for my blender landscape in case you or anyone else wanted to see the issue in a closer look.

Thanks again.

alt text

lightmapexample.png (311.3 kB)
avatar image andreschaaf Dec 15 '16 at 06:30 AM


I took a look into your Blend file. Few things here I saw

  • You have to correct the normals

  • Create a UV and a lightmap (channel 0 is UV and 1 is Lightmap) => For the lightmap: Select all faces press "U" and use "Lightmap pack" its not ideal but does its job (make soure you have selected the uv channel for lightmap)

  • UE creates its own lightmap if no lightmap channel is present

I created a new project and added your mesh. But my results are the same. I can't get the lighting right.

Currently I have no clue why this isn't working. Probably a problem with the material setup. This needs some further investigation I think.


avatar image CosmicMonkey Dec 15 '16 at 02:24 PM

Okay, so I recreated the mesh from scratch as close as I could. Then did all the UCX's and lightmap, then imported it into ue4 and some how it has fixed the issue when in unreal. However I then tested it by packaging it to an android ETC1 and the issue is still there.

This is the new copy, any ideas?

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