We're developing an isometric game that so far has had a single ground level (y = 0) for the avatar to walk on. Pathfinding for this can be solved with a relatively simple 2D AStar tile map.
We're now looking to add objects in the world that can elevate the avatar. There will be overlapping walkable areas, thus creating a problem of pathfinding in 3D space. These objects are distributed sparsely in the room, so I want to avoid keeping an entire 3D map of the room for a 3D AStar implementation. I've attached screenshots to illustrate.
What is the best way to accomplish this?