There is an app known as world painter. It is used to generate hand painted terrains for minecraft. It has a really cool feature though: When you want to paint textures, it allows you to use conditionals as to how and where the the texture can be painted. For example if you want to paint stone and grass on a cliff, you can specify that the stone should only appear on steep slopes and drops, and the grass can only be painted on level surfaces. This speeds up texture painting as you don't have to manually detail everything to make it look realistic, but with these conditionals it allows you to make more realistic maps. It can also specify at what height textures can be painted, so if you want snow, instead of just having to paint around the top of a mountain and try to make it only appear above a specific elevation or higher manually, the app can be set to only allow the painting of snow above a predefined elevation. Can we see some similar features in unity's terrain editor?