Good day, I am now starting to use the UDK.
I’m with the UDK-2014-05 release.
Performing some tests found a problem that I’m unable to resolve.
Start a standard level (Blank Map) using the Brush that comes as standard created a basis not put any textures or lighting.
Added a Static Mesh (S_HU_Deco_SM_StorageTanks03).
When I ask to compile everything (Build All), the following error message appears “Object has overlapping UVs.” I tried searching various things, but I found some very complex solutions to a standard mesh of UDK.
Does anyone know WHAT could it be?
You have to create a 2nd uv channel + lightmap:
Please post UDK questions into the UDK forum: https://forums.epicgames/forums/366-UDK because this one here is just for the UE4 
Hi Baseio,
I just wanted to chime in here and provide a little more information.
Fighters tutorial is a good place to start for fixing the issue.
To clarify why this is happening is that when you make an object for UD3 or UE4 that is not dynamic or your scene does not have dynamic lighting the light and shadow information will baked into a second UV called a lightmap. This allows you to have great shadows (if setup correctly) with no overhead of creating shadows dynamically at runtime, which can be a significant performance gain!
When an object that is static that uses static/stationary lighting in a scene the engine will look for this second UV to bake the lightmap. If there is not a second UV it uses the texture UV as the default UV for baking lighting. When it does this if there are any UVs that are overlapping it will throw out this warning. Same with the second UV. If the lightmap bakes and sees there are overlapping UVs it will give the warning. This is to let you know the shadows will not look correct because of this on some parts of the mesh.
World of Level Design has a great series of tutorials that show you how to fix lightmap issues and the general idea behind them.
If you have any questions feel free to ask!
Dear :
Many thanks for helping me. I have read all the links you sent me. It has a very good content.
I understood what you said me. When I built one mesh in a program like Maya or 3DS containing two UV maps, I may have some problems.
What I do not understand is how I can still be finding several problems with a standard mesh of UDK (I did not create the Mesh as part of the standard installation of UDK). Do you know if there is a global property about general lighting?
I have realized an enable the property “Override Light Map Res” and assign the “Overridden Light Map Res” as value 32 for this property in the individual object works. After those procedures, all the errors has stopped.
But, Do you thing I should have to do all over those objects to deal with this problem? In case, is this the better solution to do?
In other object I had to assign the value 8 “Overridden Light Map Res” property to avoid the error.
What I understood, the links you gave me has a direct impact on the quality of the shadows.
Sorry for the big text, but I’m starting now and there are many doubts.
Thanks so much for your attention. I do appreciate that.
Best regards,
I just realized that you were using UDK May 2014 build. I overlooked that in your first post. 
The same still applies. I will provide some feedback but I’m going to close the thread since this is a problem related to UDK and this forum is specifically for Unreal Engine 4.
**I have realized an enable the property “Override Light Map Res” and assign the “Overridden Light Map Res” as value 32 for this property in the individual object works. After those procedures, all the errors has stopped.
But, Do you think I should have to do all over those objects to deal with this problem? In case, is this the better solution to do? **
The default lightmap resolution on a lot of the objects will be 32. If you want sharper shadows upping this to something like 64, 28, or 256 should work for your needs. If you need better shadows for only some of the objects this would be best to up those but keep the others default that aren’t needed to be upped.
I hope this helps!