This problem is unknown to me, looks like a hardware - game issue.

System specs?

i5 2500k at 4.4
Sapphire 7850 2gb

Hmn, those specs should run just fine with Arma 3.

Try to deactivate special effects in the Arma 3 options and put everything at the lowest quality just to check if the problem does still occur.If it's gone then, try to find which option lets the bug appear
and report it.

Also newest graphics driver already installed?If not: http://www.sapphiretech.com/presentation/downloads/download_index.aspx?psn=0006&lid=1

(Some options like anisotropic filtering or anti-aliasing can be incompatible with several graphics cards at the current state of Arma 3)

I've the latest drivers, yeah. I'll have a play around with the settings and try and get a more precise bug report. Thanks for your help!

Same happen here with my hd 7970 GE and I'm running the latest driver. It didn't happen with the previous stable patch.

I'm running the default branch.

I had the same problem with the 7870 XT (Tahiti LE). After resetting the OC of the memory, I haven't seen the artifacts again yet.
It also appeared on the new lightouse in the south.

Please let us know if you are still able to reproduce this issue in latest Development build. Thank you.

Closing due to lack of feedback. If this issue is still reproducable for you, please create a new ticket for it or ask for this one to be re-opened.