I imported the Landscape Mountains demo in UE4 4.6.1 and re-rendered the scene. I ve got low res shadow only on the landscape and I don’t know how to fix it. The shadows are fine on the other meshes in the scene (see images). It’s probably a lightmap issue but I don’t know where to increase the lightmap resolution for landscape?
Increase the lightmap resolution of the landscape to something between 1-5 → you can do that in the details panel of the landscape 
Thx , it worked, I got better shadows but now UE4 crashes when I want to save the file!
Make sure to post a new thread with more information about the crash → e.g log file (project-saved-logs), the exact steps,…
Thx Figher. I think I firgured out the issue. It seems it was a pb with the DerivedDataCache folder. It was more than 30gb and there were no space left on my HD! So I changed the location and it seems ok now. I guess when you increase the lightmap on a big scene, you need a big space on your HD!
I can’t say it’s resolved as I crash when I save the project. I’ m gonna post a new thread though
I am going to mark this questions as resolved for tracking purposes, but please post a link here for your new post about the crash
Thank you,