grey spots on model

I keep getting grey spots on my model. I have redone the uv and check that the lightmap is on the correct uv channel. I have also put the lightmap size upto 1024.

This is just the default scene without any start content in.

If anyone knows why this may be happening that would be great.

Thank you very much

I have split the objects into separate models and redone the uv’s again, it helped one the larger part but when my objects get close to each other they have a dark spot areas again, AO is off for world settings.

Here’s a post with someone having a similar issue with a lot of things to consider. Also it would be useful in helping to resolve your problem to post what 3D program you are using to create the mesh, a picture of the light map, what channel your light map is set to in UE4 etc.

Moving to the Content section.

As for the issues–it’s most likely that your lightmap UV’s are messed up, or you don’t have it assigned correctly to use them or it could be something like a smoothing issue. From the screenshot you shouldn’t have a problem getting a good lightmap from that mesh.

Hi All, thanks for the help. I have9a883de4958549e794c0ddde6fa31e65c900bae4.jpeg attached the lighting map unwrap for the object. I am using 3ds max, exporting as FBX with smoothing groups on.

that lightmap needs some work, those little bits will not be picked up at all, also the corners are too tight and probably overlapping causing some of the shadowing.

If i wanted to keep the detail in the edges, how could I go about fixing this? This is the most complex shape I have in the scene. I managed to seat into the scene which is more complex than this with no issues so I am unsure how to fix this.


Like Ghiest mentioned this is likely an issue with your lightmap UVs. You can fix it manually, or generate auto uvs in UE4 and see how those do.

To make good uv’s for the lightmap do I need to sperate anything that changes direction above 80degrees, for example round any of the corners that recess back in? I tried making it one complete uv but it doesnt work. I tried auto generate uv in the program but it comes with similar issues.

Is it ok to stretch the uv’s for the light map and scale different parts?

Is this bad for this object?uvw3.jpg

I got it to work but with huge light maps, 2048. Can’t find a solution for this. I guess it’s light bleed but not sure. I’m new to all this, I am a vray user.

The areas where you have too many lines close to each other are too dense for lightmap texture to work properly.
Need to relax those areas and these dark spots vanish.

Thanks, I will try spreading them out and see how that works out for me.

You need more spacing between your UV islands, you should be able to get a good bake at 128 with a mesh like that.

I have set this up for 128 with 3 between islands. This still produces the errors I am having. If it put it up to 1024 it works. But from what I have read the set up I have got here for 128 should be OK.
Thanks for all the help everyone

If you post a download link for the obj file, I’ll see if I can get better results and post an explanation.