Hey all so I've been posting stuff in the PP section during th course of this project for school. I'm a first time noob at modular workflow so bare with me. So far, I've been making the square power of 2 textures first(or some un-square iteration), putting them into a 2048 texture atlas, and then just breaking the chunks…
Some pieces won't always be clean power of 2 in PS, for example if you wanted any 45 degree angle wall its gonna stretch your UV unless you unwrap. Here is a good resource http://www.philipk.net/tutorials/modular_sets/modular_sets.html