Gaïa is a tool made by Procedural World for Unity Engine that provide you to sculpt a terrain in 3D with multiple parameter.
My Workflow
It work as a stamp on the terrain using a grey map.
To create a map, first, i need to create a Stamper which is an area where the grey map stamp will be applied.
After choosing the stamp, i can tweak some parameter as the position/rotation of the map or the general topographie of my map.
I obtain this preview of the futur map and after creating it i get a fully terraformed terrain.
Then i can create spawner for graphics and art assets.
If the global topographie seems good, i can spawn ground textures.
Those spawner work with rules i define before the spawn, so if my rules are good i could not have a grasse texture at the bottom of the ocean.
Placement rules parameters
After the generation of the textures, i obtain something like this.
As you can see, my rules are well followed and my textures are placed by a naturall way.
The next step is to spawn some vegetation and rocks, and starting creat life in my map.
With the same way, i add some detail as grasses meshes, flowers... every of these spawned object follow rulles likes the textures, trees and rocks.
To finish, just adding water, post processing and wind zone and my map is finished.