Hello,
I created a landscape and applied a very simple shader but I can see the different chunks they seem to have different illumination properties :
http://puu.sh/iSG5M/5959475388.jpg
Could someone point me to the settings I need to change to remove the visible seams ?
Thanks a lot,
Max
Hello yamashi,
So before you build your lightmaps, assuming that you are using static lighting, you will see seams on the landscape where the grid tiles. Under the option build at the top of your HUD change the lighting quality settings to production and then build lighting only. This should go away.
The picture above is a production quality after building the lights, that’s why I am concerned 
Hey yamashi,
I have recreated what you are experiencing inside of UE4. Whats happening is the static light maps in your scene are creating some artifacts where the terrain has seams. Unfortunately there is no way to hide these seams like you would on an imported mesh where you can choose where you want the seams to be. When you use static lighting, the maps and shadows are baked onto whatever the light or shadow is being cast on. Wherever you have seams there will always be a slight amount of artifacting because the lightmap is trying to calculate a space that essentially has no RGB information. Thats why in games/movies there are different techniques used to hide these from the viewer/player.
The quick fix is to change your lighting setting in whatever lights you have in the scene.
Best quality for reducing lighting artifacts is movable, medium stationary, and worse static.
Try changing your lights to movable and bake them out again.