tactile graphics (Score 4, Informative)

The first thing I thought of when reading your question was "tactile graphics". In my experience, it's the best way to convey spatial distances when one can't see the distances. A tactile graphic is, for example, a map with details raised, effectively making it so that the individual can "feel" the distance and relation of different features. The drawback is that these graphics are expensive *and* tend to be very large (it's difficult to feel the separation of two tiny lines when they're close together). A quick google will find you plenty of information on companies that make these products. (I happen to work for a company that makes tactile gfx, in addition to other low vision/blind products, but no plug for them today)