14 January 2010


Photosynth is a relatively new application from Microsoft Live Labs which takes a group of related photographs and analyses them to produce what they call a 'three-dimensional point cloud' of a photographed object or scene. Following that, the Photosynth browser plug-in allows one to view the object from any angle, limited only by the quality of the photographs and the extent to which they overlap.

Which all sounds very interesting. It basically means that you can move through a Photosynthed scene to see the photos from any angle, or to zoom in on areas of interest. You can see the actual position from which a photograph was taken, or look for the same scene from a slightly different position. Furthermore, because it's an online application, anyone can use it... or that's the theory, anyway.

Practically speaking, at present Photosynths can only be created on Windows Vista or Windows XP. Using Silverlight, anyone can view them, provided they're willing to install Silverlight. Perhaps one day there'll be true Mac or Linux support, but this is Microsoft Live Labs - why would it ship for anything other than Windows? Why would it embrace HTML5, or even, at a push, Flash?

Regardless; there are two stages to the Photosynth experience. Uploading and analysis is the first step. Your set of photographs are subjected to an algorithm that matches points of interest. Little chunks of image which appear in a range of photographs are matched up, and the program uses this to calculate the three-dimensional relationship between the images. Angles, distances, perspective - it's all put together into a 3D scene. They call it bundle adjustment, though it might as well be called reticulating splines for all I know, and in fact that might have been geekily amusing, had they thought of it. 'Bundle adjustment' sounds good, however, and once you've completed this one-off, rather computationally-demanding process, you can move on to step two. This is where the 3D point cloud is navigated using the Photosynth Viewer. The server stores the original photographs, and the client does the displaying and requesting. Natively, if you're a Windows user, and via the delights of Silverlight if you're not.

So, after reading all about it, looking at the comments on slashdot and the videos on YouTube, curiosity got the better of me. I played around for a short while and never quite got round to uploading my own photographs. It was interesting, and I had a bit of fun getting lost on the outskirts of the Taj Mahal, but in the end it was all rather underwhelming, considering the hype. At the moment, I feel there's more excitement imagining the underlying technology than actually using it; it takes me back to the days of finally managing to get the library to order The Science Of Fractal Images for me, or Martin Gardner's mathematical recreation columns. Maybe when there's a Mac version, I'll have another go, but at the moment it's not really worth rebooting into Windows for, let alone selling out and installing Silverlight.

http://photosynth.net/, if you're interested. Despite the amazing concept, I'm nearly ashamed to admit that I'm clearly not.

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