Map Projections

I first learned about cartography and mapping technologies back in 2007 or so when I was working on Danger's bluetooth stack.  In order to test my work on the serial port protocol (SPP), I connected to a bluetooth GPS "puck".  This led to finding interesting things to do with that data, namely a mapping and location tracking application.

Back to the present... As part of trying to find a really interesting project to really drive my web development goal in my spare time, I've been doing a lot of reading on map projections again, looking into what's required (technically) to convert things like park maps or trail maps into something that could be overlaid on a map.

Here's the 30 second background summary: Since the earth is a sphere, but your screen is a rectangle, some magic is required in order to display maps of the earth on your screen.  This magic is actually mathematics, and is called projection.  You can liken the problem of projection to the problem of flattening out an orange peel on a table top.  You can do it, but there are trade-offs involved.

There are some really interesting projections out there, but popular maps on the web use the Mercator projection.  This projection is accurate around the equator, but more and more distorted the further north and south you travel.  This projection is popular because it flattens out longitude, so that they orthogonal to latitude, making for a nice x, y coordinate system that is intuitive and square, among other things.

It may blow your mind to realize that what you think you know about the earth is actually wrong... or distorted, but what does that mean for trying to display a park map as an overlay on one of these Mercator maps?  It depends on the projection of the map of the park, but generally it means that the park map will have to be distorted to fit the faux reality of Mercator.

Figuring out and applying that distortion is what I'm interested in, and has led me down all sorts of interesting paths over the past few days.