When I saw this article about the discovery of a tracking file on iPhones that records location in a hidden file, my first thought wasn't about privacy. As a data viz geek, my first thought was: "I've gotta see this". Fortunately, or not, there's an app for that. At least a desktop app that you can download here and, provided you have synched your iPhone you can check out your travels and locations over the entire time the file has been recording, or on a week by week basis.
So here's the trip we took last August from Connecticut to Mt. Vernon Ohio and the return trip via Pittsburgh:
As you can see, the cross country drive has a good deal richer data, especially as it is shown at a greater scale than the London data. The London data seems to be showing our location over a set of grids that could be cell towers or could just be a mapping grid. As far as the size of the dots, we did spend a bit of time in Chinatown/Soho, so there is some sort of accuracy there.
The trip CT-OH trip data is much richer and makes me almost immediately think about the trip itself, the experiences we had and the possibilities for annotating this with images and text and turning it into an even richer document. The funny thing is that this reminds me very much of the kind of use cases I heard very early on for geolocation apps like Foursquare. Along with the idea of connecting with friends the other thought I had heard expressed was the idea of simply leaving a record of your travels that you can always refer back to.
Turns out we've been doing it all along.
Oh, and then there's that privacy thing. That's a whole other question.