Thursday, February 21, 2008

My Route

What started as an innocent curiosity expedition with Google Earth turned into a rather longer journey through data manipulation, which I will explain presently. What I was trying to do was plot an elevation map of my ride to and from campus. Since I commute by bike, elevation changes are important: to be sought out if I want a workout; to be minimized if I'm low on energy. If it was easy enough to do (it was not, with present tools) I was going to plot out several routes and compare them based on elevation profile.
In any case, here is the elevation profile for my route when I ride along Shoal Creek Boulevard:

To get this, I first drew the path in Google Earth and exported the path as a .kml file. kml is the "keyhole markup language", a sort of xml for maps. Unfortunately, and this is a BIG unfortunately, Google Earth does not include elevations in its exports.
It turns out there is a web service for filling in the elevations, though, found here, which is cumbersome, but ultimately useful. I copied out the trip coordinates from the filled-in kml file and reformatted it so that Microsoft Excel could read it. Then, I put in formulas to convert latitude and longitude to distance traveled, and plotted the results.
I know this can all be streamlined, and maybe I'll make a minor goal of posting a one-punch processor for turning Google paths into elevation profiles. In any case, it's kind of cool to see the result. My trip is semi-hilly with about 50 meters net elevation change from school to home. Overall, the ride home has 213 meters of climbing, and the ride to school has 94 meters of climbing.

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