Lightmap help

Hi, im having issues when it comes to UV lightmaps and shadows not casting correctly, after importing from Maya 2015 to UE4.
No matter what settings I try and no matter if I try exporting the mesh in several smaller parts with separate UVs it seems to have the same issues none the less.
The issues im having are shadows being round even though the house is completely square and only having sharp edges at the moment, and also lightbleed from the roof.
Here is a picture showcasing shadows in the corners of the house.

And here is a picture showing some lightbleed from the roof of the house:

And finally a picture of the lightmap itself:

I’m completely new to importing models and modelling in Maya, and lightmaps seem very complicated to get to work properly for me.

Hi GrafithZ,

What is your light map resolution? It looks to me like the very narrow uv islands are to small. Try cranking your lightmap resolution for this asset up to 2k as a test. If it lights okay, they you can assume that your uvs are not efficient enough and need a better layout. You can then reduce the light map resolution to a more reasonable size and re-do your layout more efficiently. If this is the case then scale up the very small islands so that they cover more than just one or two pixels of the light map.
If you are looking for more information about laying out good lightmap uv’s then I would recomend these pages: UDK Lightmap Common Problems, Errors and Solutions
Best wishes,

Matt Cooke

Thanks, the 2k lightmap resolution made the shadows much better but the light is still glaring through the roof/wall. Not sure what is causing this, tried using a BSP or something different as a roof but the light still glows through. Guessing a more efficent lightmap will do the trick, thanks for the help!

Hi again, I seem to have gotten around the weird shadows, even with lower lightmap resolution, but I cant seem to get rid of the light seeping through the roof/top of the walls…
This is built with only one specific mesh:

And the lightmap looks very simple and padded, or am I wrong?

If you turn off your directional light and use a static (ie. baked) spot light, coming in at the same kind of angle, do you still get the same problem?

If this fixes the issue then it could be light bleed from the dynamic lighting. If this is the case, try adjusting the shadow bias of the directional light.

Best wishes,