Photosynth started life as a set of desktop tools (Image Composite Editor and the Photosynth applications), and later expanded to mobile with a version for the iPhone. The desktop tools can take in photos captured from a digital camera and combine them together by comparing the images (a relatively processor intensive task).
You might think a smartphone lacks the muscle to do this but smartphones can cheat by using their on board sensors to provide additional positional information about each photograph. Essentially the data from the accelerometer, gyroscope and compass sensors are combined together so that the phone "knows" which way it was pointing when it took the photo. This extra information reduces the amount of processing needed to combine photos together.
The video below gives a brief demonstration of how the Photosynth app works on Windows Phone and shows an example of creating and viewing a panorama.
Starting the Windows Phone version of Photosynth drops you into a panorama with capture, library, and featured pages. A single tap on the capture page starts the process of capturing the photos needed to create a panorama. Holding you phone up in front of you, pan around slowly, and let it automatically capture pictures as you go. In some cases, it may be necessary to manually capture a photo (e.g. filling in an awkward space). The capture is free from, you don't need to move in one orientation, or even in one pan motion. Indeed to collect a complete "sphere" panorama you will need to break upwards and downwards from the horizontal pan.
Once you've finished capturing the scene around you, tap the tick button and the app will start the stitching process, combing all the photos into a single panorama. There's obviously a lot of processing going on here, so depending on the number of photos you've taken, the process can take anything up to a few minutes (smaller panorama, consisting of a handful of images, will take around 30 seconds).
When the stitching process is complete, the finished panorama is automatically loaded. You pan around the panorama using swipe gestures, and you can zoom in with a pinch gesture to view additional detail.
All the panoramas you create are stored on your phone, accessible from the library page of the main panorama, but you can also opt to upload them to the Photosyth website, or share them with your friends via Twitter of Facebook.
The featured page of the app's main panorama showcases selected panoramas from other users. It's a great showcase of some of the very best panoramas that have been uploaded to the Photosynth website (though do note, lest you feel your own efforts are inadequate, that the featured panoramas are not necessarily captured using a smartphone).
Marketplace description:
Photosynth for Windows Phone is the panorama app that makes it easy and fun to capture and share interactive panoramas of the places, people, and events that are important to you. Using the latest in computer vision techniques, Photosynth is the acknowledged leader in mobile panorama creation. It is the only app available on any mobile platform that allows you to capture 360 degrees horizontally and vertically, making a perfect “sphere."
Once you’ve created a Photosynth, you can share it as an interactive panorama experience on Facebook and Twitter (using the free Photosynth.net service) or as a simple image. You can also publish your panoramas to Bing where millions of people will see your panoramas, on Bing Maps and in Bing search results for the places you've captured. And check out our featured list, where we show off the best of what you and your fellow users create and share.
Photosynth can be downloaded from the Windows Phone Marketplace for free. The app works best with devices with the full complement of sensors (e.g. Lumia 900, HTC TITAN). Other devices (e.g. Lumia 800 - no gyroscope) will work, but they may have decreased sensitivity in the positioning information. Due to the processing and memory required to stitch panoramas together, devices with 256MB RAM (e.g. Lumia 610) are not supported.
An example Photosynth panorama is embed below (Silverlight required):