This process is known as Z-Order Curve (http://en.wikipedia.org/wiki/Z-order_(curve)). You can quickly get to an index in memory or a cell/location on the map using Morton-Encoding. It is also known as a Linear Quadtree.
Foundations of Multidimensional and Metric Data Structures is a great resource! Check it out at http://gisandscience.com/2009/08/21/award-winning-book-by-ha....
Similar, but without sacrificing accuracy for built-in zoom information. Due to it's layout, they also support using bit -wise operators for all of their operations (since in reality these systems are all just interleaved x/y bits)
It's based on the hilbert curve.
Once you get past the inexplicably florid and fervent language (it's a spatial indexing scheme, guys—not a holy revelation!) there are a couple of cool qualities that stand out to me:
- The distribution of indices is very even over the globe. Yes, this scheme is specifically suited to indexing space on a globe, and not much else.
- You can be arbitrarily precise by specifying a longer index. Truncating that index just makes it less precise. A major benefit that springs to mind here is the ease with which you could then query for overlapping indices.
- Subdividing space by placing child indices at both cell vertices and centroids means there is always overlap between cells at neighbouring resolutions. Whilst this does make the scheme a tad inefficient in terms of storage (which may or may not be the most important detail depending on your application) it has the really neat consequence that any area smaller than a continent is guaranteed to fit wholly within a single index at some resolution. Schemes that avoid overlapping indices or coordinates for the sake of efficiency can never have this property.
(I stumbled upon PYXIS while looking for an addressing scheme to rip off for a game project I was working on years ago. Ultimately I decided that PYXIS was not well-suited to my needs and took a much simpler approach, but its novelty stuck it firmly in my mind anyway.)
"As an alternative, the Hilbert curve has been suggested as it has a better order-preserving behaviour, but here the calculations are much more complicated, leading to significant processor overhead."
0xDEADBEEF would represent about a .14 mi^2 area. I wonder where it would be... Guess I'll have to implement it to find out! :)
That doesn't mean it isn't nifty, of course.