3D tile-based field-of-vision

G'day forum,

I've been prototyping a turn-based-strategy game, and have written a permissive FOV implementation so that characters can calculate which tiles are visible from any tile on the map.

I'm redeveloping some of my core systems for the game and want to 'upgrade' to a fully three-dimensional tile map, so that I can have multiple floors etc.

What I'd like to know is if anybody has had any experience implementing a 3D FOV system into a tile-based game before, and knew of any good reading/resources on the subject. So far I've encountered only raycast-driven solutions, when it seems perfectly reasonable to expect that there should be 3D implementations of Shadowcasting, Diamond FOV and Permissive FOV in the wild somewhere.

 

I've only used raycasting solutions myself, but most of my tile implementations are overhead (iso-like) constructs - so more like 2.5D.