Saturday, April 16, 2011

Ready for a nice vacation to Greece? My blog is all you need! :) (PhotoSynth)

Who needs time consuming trips to other countries when you can have it all here, on Siderite's blog, embedded in a blog post? Of course, if you would like the real deal (Hmpf!) don't hesitate to contact me. I can guarantee very good prices and the total trustworthiness of the people there. (You will need Silverlight to see this)



You can access the same Photosynth by clicking on this link: Villa in Kyparissi, Greece on Photosynth.

Now, before you start thinking I've gone into tourism marketing, let me explain the technology, what is Photosynth and how to use it.

Photosynth is a Microsoft Research baby and one of the things that they should be terribly proud of, even if not many people have heard of it. I blame this on bad marketing and the stubbornness on using Silverlight only. If you are to read the Wikipedia article, the technology works in two steps. The first step is photo analysis with an algorithm similar to Scale-invariant feature transform for feature extraction. By analyzing subtle differences in the relationships between the features (angle, distance, etc.), the program identifies the 3D position of each feature, as well as the position and angle at which each photograph was taken. This process is known scientifically as Bundle adjustment. You can see it in action if you go to the villa and chose to see the point cloud. The second step is, obviously, navigating the data through the Photosynth viewer.

Now, how does one use it? Surprisingly simple. First take a bunch of photos that overlap themselves. You can use multiple cameras, multiple view angles and times of day, which of course does complicate matters, but the algorithm should be able to run smoothly. Then download the Photosynth software from their site (make sure you have an account there as well) and feed the photos to it. Wait a while (depending on how many photos and their quality) and you are done. I especially liked the option to find the place in the synth on Bing maps and select the angle of one picture in order for it to determine the real location of the objects in the photos. It will also use geographic information embedded in the pictures, if available.

There are, of course, problems. One of the major ones is that it is all done through the Photosynth site. You cannot save it on your HDD and explore it offline. Also, it is not possible to refine the synthing process manually. If your pictures are not good enough, that's it. You will notice, for example, that none of the images rotated to 90 degrees were joined to any others or that there is no correlation between the images of the house outside and those inside. One cannot remove or block pictures in the synth, either. Being all closely connected to the Silverlight viewer also reduces the visibility of the product to the outside world even if, let's face it, I have edited the Photosynth by adding highlights and geographic position and I have navigated it all in the Chrome browser, not Internet Explorer, so if you refuse to install Silverlight to see it, it's a personal problem.

I hope I have opened your eyes to this very nice and free technology and if you are interested in a vacation to the place, just leave me a message on the chat or in a comment. If you have read to this point, you also get a 10% discount, courtesy of yours truly :)

Update: Here is a bit of interesting news, the release of a Photosynth application for iPhone. I personally distrust Apple products, but even Microsoft seems intent of getting a piece of those.

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