Saturday, August 23, 2008

Photosynth

Microsoft's new Photosynth is probably one of the coolest bit of technology released by the company in years. It is the product of Microsoft Research and a number of computer scientists from my old alma mater, the University of Washington. Photosynth is a web service that runs through a browser (Windows only for now) that takes stacks of digital photos and merges them into a single, mind-blowlingly cool 3-D arrangement. This is like a 3-dimensional panorama and ideal for photographing subjects where you want an overall view but also the ability to "drill down" to see detail. And Photosynth does this without any preset reference points -- it just takes the pile of photos taken from every crazy angle and matches up points across them all and then produces a 3-dimensional view.

One of the great thing that photosynth does for me is allow me to take blimp photos that have all sorts of yaw, roll, rotation issues and merge them into a single viewable entity. I've been working on this problem for a while - though a wide range of panorama building software (e.g., hugin, Panotools, Autopano, PTAssembler, Tatuk AIC, ArcMAP, ERDAS, DoubleTake, PTGui Pro, and many others). The problem I have is that the photos are so uncontrolled in the blimp in terms of their orientation and distance from subject (much less the issue of the ground topography) that the solutions are not very good and it take a lot of manual work to fix them (if that is even possible). The best solution Ive come up with right now is either Adobe Photoshop CS3 "PhotoMerge" option or PTGui Pro (though DoubleTake is great for a small # of photos). Both seem to work best when the camera has a constant height, the images are sequential, and the topography isnt too lumpy. That's great but it's not easy to achieve.

Photosynth really changes all of this since it is built to examine 3-dimensional things. It does a remarkable job of merging photos together that vary in height, roll, yaw, resolution - easily the best I've ever seen. Now, first thing others ask me about these products is whether or not you can "flatten them" to put into GIS -- that doesn't currently seem possible (it would require more processing to do integrated projection of the aggregate set of images). Ideally, that will be forthcoming but who knows (its free as it is). But as it stands right now, it is a powerful (and easy!) way of visualizing an archaeological landscape with all the detail you can possibly want (depending on your camera and the load on the photosynth servers - it has been pretty popular since being listed on Slashdot).

Here are a couple of the "synths" I've created in the last few days:

Easter Island: Rano Raraku: Rano Raraku - 2

Easter Island: : Akahanga-Easter Island

Guatemala: Cotuzmalguapa

Greece: Mycenae Acropolis

Greece: Mycenae - Lower Town

I'll post more as I create them.

Also, you might want to check how this works and what they have in mind for the future (imagine having a cumulative set of images from everyone in the world for any place) http://phototour.cs.washington.edu/findingpaths/

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