rebuilding a city from vacation photos

Dear Digital Archaeologist,

I'm so excited! I think I just caught a glimpse of your future work!

Many people take photos using digital cameras. Once they do, they need some way to share them, so over the last few years we've seen the rise of photo sharing sites like Flickr. Sometimes, we see people collaborate in a self-conscious way, like posting images from around San Diego during the wildfires and tying them to a map. Often, though, the coordination is unconscious, such as several people taking pictures of a historic landmark like the Statue of Liberty.

Now, for the first time, a group of researchers has written software that pulls together those pictures to build a three-dimensional representation of the landmark. The principles are fairly simple--they've been known to the technology of computer vision for some time--but there are some tricky parts like dealing with obscured images and calculating backwards to find out where the photographer was standing when taking the photo. The researchers are already talking about trying to recreate entire cities digitally using these uploaded photos.

Is this one of the things you do? Collating photos from our age, figuring out which ones occurred at about the same time, and using them to rebuild maps and three dimensional representations of our cities? Or is that just the start? Are you doing far more sophisticated analysis, such as using the sun's angle to tell time of day and then discerning daily traffic patterns based on where people stood when taking the images or having their images taken? Or discerning the chemical composition of our air by using photos to assemble an absorption spectrograph of sunlight passing through the atmosphere? Or estimating cloud cover based on shadows?

Of course, I've assumed those images survive intact. You might instead be so far in our future that you're happy to be able to assemble a single coherent image by combining the fragments from a thousand different disk sectors, trying to fill in the gaps in bit-rotted jpeg files.

In any case, I wish you well. I hope this message--or most of it, anyway--reaches you in good health. And if you're a grad student, best of luck to you on your thesis work.

Sincerely,
False Data