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  1. #1

    Default Weird, non-smoothed lightmap issue.

    I'm having this odd issue on one of my meshes, where the lightmap is all checkered, and not nicely smoothed. I've been searching the UDN knowledge base and whatnot, and several forum posts, and tried the following fixes:

    -Encase the level in a BSP brush room, so the light traces don't have to travel far.
    -Re-import the mesh that's giving issues.
    -Re-do the smoothing groups.
    -Add a proper collission mesh.
    -Make the mesh one-sided. (as it was two sided before).

    The mesh has no volume. It's a plane, with no backside, and no actual interior. I'm talking about the curved wall that also acts as the ceiling as it goes up. Check the picture below. I'm using a Pointlight to light the room, which is located inside the small gap in the wall, combined with a Movable Pointlight, also in the same location. That gap is part of the same mesh. This is Production quality light.

  2. #2
    MSgt. Shooter Person
    Join Date
    Apr 2011


    whats the lightmap resolution on the mesh?

  3. #3


    256. I tried both lower, and highest resolutions. The only thing it resulted in was increasing or decreasing the size of the unsmoothed light squares.

  4. #4


    Higher lightmap should make the quality better. Are you using lights or emissive materials for lighting?

  5. #5


    Like I stated in the OP, I'm using a Pointlight to light the room with Lightmass, and a MovablePointLight for the sharp shadow. A LightmassImportanceVolume encompasses the entire brush-room around the scene.

    Screenshot of what happens when I turn the resolution to 2048 (which would be insane anyway). As you can see, smaller unsmoothed squares. Note that the floor is also a mesh, and behaving just fine, with a smaller lightmap resolution.
    Last edited by HoratioWryer; 03-01-2012 at 06:34 AM.

  6. #6
    Join Date
    Jan 2008
    Cambridge, UK.


    what are you exporting it from? also does UDK give you any errors when importing?

  7. #7
    The Sacrifice
    Join Date
    Dec 2011


    Is the material normal mapped? And have you fiddled with the normal map detail lighting settings in the world properties?

    edit: Have you tried a different material just for fun? Try making a simple material with a constant three vector in the diffuse see if it does the same thing.
    Last edited by KingMango; 03-03-2012 at 03:46 AM. Reason: added troubleshooting suggestion

  8. #8


    Exporting it from 3DS Max, like the rest of my meshes. Exporting to .fbx without too much altered settings. The material is indeed normal mapped.

    I did try to change the material, but the error persists. I'm going to rebuild the mesh from nothing, to see if that does anything. Thanks for all the help. I hope this works, getting frustrated.

  9. #9
    MSgt. Shooter Person
    Join Date
    Jan 2012


    Lightmaps are probably the biggest current fail in UDK - everyone and their dog is having issues with them. Are your meshes modular? or just one big one?
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  10. #10
    Prisoner 849
    Join Date
    Feb 2010


    You can resolve that issue by turning off lightmap compression in BaseLightmass.ini. The file is inside Engine/Config/ folder. Change following to False.

    Be warned however, that it will increase size of your level by 3 times at least. There seems to be little or no performance issue with it however. A good compromise may be to turn off compression and use smaller lightmap size.



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