There is someone on devianart that was making the maps. Basically doing them in 2D from scratch.
This is one for the persons working on it: http://bulbapedia.bulbagarden.net/wiki/User:Nuck_Chorris So I think its grab individual screenshots of things (like trees and buildings) using the code I provided for nsbmd viewer to work for most pokemon models, then use photoshop/paint to make things look good.
Wrong. It is possible to create maps using screenshots. There's an Action Replay code that "flattens" everything as if you were in a building. That's how this map from Bulbapedia was made.