Terrain editor

Terrain are special objects that can be instantiate only one time per scene.

A terrain is a tessellated plane that is displaced basing on an heightmap. It can be sculpted and painted with texture splatting.

Terrain editor can be used for creating / editing:

If you have already created the terrain in your scene, Terrain editor can be opened in 2 ways:

Once you gave opened the terrain editor, the Scene Viewport is opened, if it wasn't already, together with the terrain panel:

The contents of 3.4.10. Terrain editor