My First Photosynth

If you don’t see anything cool above this sentence, you probably need to install the Silverlight plugin.

If you still can’t see anything, try viewing the synth directly at my page on Photosynth.net

Got it? Good.

What you see above is a “Synth” of the fish ladder on the Grand River, just north of downtown Grand Rapids, Michigan. I created it using Photosynth, a piece of software created by the brilliant folks at the University of Washington and Microsoft.

In a nutshell, here is how it works: Find an interesting object. This could be a building, a car, the space shuttle, someone sitting still, or anything else which is not moving. Take lots and lots of photos of that object, from many different angles and elevations, all around the object. You will probably want to take at least a dozen, and a few hundred is not unreasonable. Once you have your photos, import them into the Photosynth desktop client (Windows only, for the moment), and go make a sandwich. This part takes a while.

Once the tool is done synthesizing the photos, it will give you a link to your page on Photosynth.net where you can interact with your new synth. All the instructions for viewing are there on the page if you click the “?”. You can see the scene as a series of 2d slides, in 3d space, as a top view, or as a point cloud.

As you click around you will see that there are a couple of glitches in the viewing experience. As near as I can tell, this is because of two problems with using the fish ladder as the subject of a synth.

First, I couldn’t get photos from every angle, all the way around the structure. There were large degree arcs where I could only see part of one side of the sculpture, and others where I could only see the sculpture from up close, with no surroundings in the photos to provide context.

Second, the structure is hollow, and from many different angles the interior walls are visible. I think that the software became a little confused when trying to match up specific shapes on the photos, when it was not clear if I was inside the sculpture looking out through a doorway, or outside looking in. The fish ladder is uniform gray concrete, with many non-right-angle surface intersections. Photosynth does a good job of mapping points of interest onto a 3d space, but I think that shapes which are different at one level of zoom, but similar at another, cause it to take a “best guess”, which isn’t always right. Example: The corner of a doorway, viewed from straight ahead, is a 90 degree angle. Viewed from directly in front, looking up, it is closer to 45 or 60 degrees. Now find another part of the sculpture where two walls come together at 60 degrees. And make it all uniformly gray concrete.

On the other hand, if you like non-Euclidean experiences, maybe this isn’t a problem.

For a good overview of Photosynth in action, see this video:

Demo of Photosynth at TED

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