well you can actually paint terrain heightmaps using the editor, if you just wan tto start with basic terrain texturing. u can use it to paint texturelayers aswell. but i recommend using other unreal editors for painting terrain textures since the one here on this forum tends to crash whenever it wants ^^
Just open the Editor and use a nearly empty example map to get map dimensions. Here I am using 15_22, since it has asingle water volume and a plain terrain texture only. perfect for demonstration:
Open terraininfo and move the terrain layer up the Z axis so it will stay slightly under water:
Open Terrain Editing Tool und use the Paint method to raise terrain in order to create an island:
now that we have edited our ground heightmap texture in order to save it you must save the texture file using the texture viewer (before editing the ground u need to open it with the texturewiever). In our case it is T_15_22.utx. Just save it by klicking on File->Save. Overwrite the existing T_15_22.
Now by opening15_22.unr our ground will be under water again (bcs. we didnt save the .unr map file), but still have our edited raised ground part.
U can use this method to raise actual ingame ground parts on retail maps ^^ In order to actually paint the ground and the ground textures I would recommend using another UE. The one u will find here tends to crash and malfunction a lot. for example you cant flatten terrain using terrain brushes. Also texture painting doesnt work correctly aswell. sometimes u can paint and sometimes it does nothing.
To paint texture layers, select a texture in your "texture viewer" and use the "layer" tab
To paint 3d grass choose a grass mesh type and use "decoration" tab tocreate decoration layers (eg. grass, little rocks and any kind of debris
So by using another Editor you can edit and create plain textured terrain. Just check the dimensions of the original map to create a compatible terrain texture
Note: This should not break your map's lightning since we are editing a texture only. Also note that raising the ground will not raise the position of static meshes that already exist on your map.