…Can be found at NASA here
Photosynth is a microsoft project that merges many 2D photos by calculating the position, orientation, and camera charactereistics of each photo relative to other, overlapping photos. Images are matched by finding common features in two overlapping images, much like panoramic stitching software – the difference is the plug-in viewer, which has an intuitive exploration mode and also maps out a sparse 3D image of the total scene by depositing pixels in 3D space where significant image features are found. The key to this is Feature Detection that is scale, rotation, illumination, and perspective independent, so that an image of, say, a statue, can be found in multiple photos, regardless of the time of day, position, relative size, and rotation of the camera. It’s of course not perfect, but it is quite robust, with the one ‘disadvantage’ being the initial time it takes to create a photosynth environment from the initial photos. This fortunately does not impact download or playback performance as it is a one-time computation.