Imagine that you stood in one place and took a bunch of photos in different directions. Now imagine that you printed these photos onto glass sheets and arranged them in the same planes that they were shot: the picture you took of the sky is horizontal, facing down. The mountain off to the left is upright and facing right.
Now imagine that these pieces of glass magically intersect to make a lattice which you can turn to view, and that those pieces of glass disappear from view when they are edge on.
You just imagined Stilla, a great new iPhone app which does all of this for you, without harming a single sheet of glass..