Tuesday, April 28, 2009

Analyzing the Flickr location tags...

I just ran across this article in New Scientist, but have been thinking a lot about the use of geotagged photos and some possible expansions to it. With just location, it's interesting to view a set of photos, just what are people taking pictures of at the Apple Store in Manhattan? It's the fifth most photographed (and geotagged) place on Earth. Is it the facade? Inside? Most of the GPS-based automatic image tagging devices wouldn't work inside the store. And although there's a lot of interesting data here, it can't really be used for an immersive experience since there's no pointing information at all. Let's think of the Washington Monument, some photos are outside, classic tourist shots of the monument, some are facing away from it, catching other aspects of DC, and some are from the top looking around. Image if each image had orientation data associated with it, a fluxgate compass as well as the GPS location, then you could tie a large number of images into, say, Google Maps, and move around in a collage of photos. Okay, this still doesn't work inside too well, but for outside it would pretty spectacular. You could walk 42nd Street in photos at Christmas-time last year, or watch the parade go by.

The next step after that would either be computer detection of the horizon-line in the image (I didn't bother to Google the efforts that must be going on in that direction) or tilt sensors in the camera. With focal length data, position, pointing, and tip/tilt, each photograph would be a capture of a well-defined piece of the world at that time. A 3-D immersive virtual reality of collected photos, might be a nifty thing?

So, hardware-wise, what does this look like? Well, GPS, 3-axis magnetometer, and 2 absolute angle sensors are just a couple of chips and some MEMS. Might be able to add in a low-power inertial navigation unit using fiber optic gyroscopes in version two. That should keep the position information good within a walk through a building letting you get your tagged full-orientation photos of the inside of the Sistine Chapel and the Louvre.

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