That sounds similar to some anti-aliasing problems with FE:

https://forums.elementalgame.com/430477

I think I've read something about a new graphic engine for LH. Do I remember correctly? Has the way AA is handled changed from FE?

The issue occurs with the Raedon 7970m also on both FE and LH.

That's interesting does it resolve the issue for everyone if they disable Adaptive multisampling?

Since some ATI-videocard users experience the type of AA problem described in this thread's OP, as I also noticed on a few forum threads, allow me to give the detailed steps to follow :

1. Launch the Catalyst Control Center program (= CCC.exe) ;

2. Go down to "Gaming/3D Application Settings" ;

3. To the right, on line 4, at "Anti-Aliasing Method", click on the "Multisampling" option (in the drop-down menu).