Terrain tool : generating a "wall"?

I’m currently trying to draw walls using the terrain tools. It’s with this tileset, specifically : http://opengameart.org/content/cave-tileset-0
The way i tried to do it is having one terrain for the ‘top’ of the wall ; one for the wall itself ; and the ground whenever it is visible around the 2 other kind of terrains.
But it is delicate and gives results somewhat trippy, albeit a bit random and uncontrollable.
I don’t know if it is recommended, and controlable to have more than 2 terrain types for one tile ; plus i don’t know if there is a more clever way, with the terrain tool itself, to have it all work. Currently i’m more going towards a AutoMap based approach, but it’s more time consuming of course… and i’m not sure i can replicate all the features of doing a terrain… but there is a certain upside to the AutoMap : the layers are separated, which i’m sure i’ll surely find useful with all those walls.
I should add that i’m at the beginning of using this tool (though i’ve spent some time on it already…) so there must be a ton of things i don’t know !

Right, this is not a use-case that the terrain tool was prepared to handle. Defining the middle of the wall as another type of terrain is a hack that is very likely to run into limitations of the tool.

In the game Source of Tales we’ve also done the terrain layer using the Terrain tool but then had another layer on top for these vertical cliffs, for which we’ve used the automapping system instead. Automapping was also used to generate trees of random height with the tiles in the right layers.

Thanks for the info ! That’s actually close to the solution i used : a terrain that draws only the top of the wall, then an automap that draws the actual walls on another layer ; and a third “base” layer that draws the ground. Actually, it feels like a pretty neat workflow.

So, I checked out source of tales on github (https://github.com/tales/sourceoftales) to try and figure out how your automapping worked. However, in the automapping directory, there is no rules.txt. Can you help me with that?

Nevermind, I’m an idiot… Just realized I should be in the maps directory, not the automapping directory. My bad.