Enter the Seadragon...

Photosynth incorporates Seadragon's amazingly smooth digital rendering and zoom capabilities.

Acquired in February 2006, this technology features:

• The fastest, smoothest image zooming you've seen — Whether it's 1 megapixel or 1 gigapixel, Seadragon can open any image in a flash, and zoom and pan with buttery smoothness. Images "come into focus" continuously as data comes across the network, and the speed of this focusing is determined only by your screen size and bandwidth, not the size of your image.
  
• Big collections? No problem — Seadragon can browse collections of many thousands of full resolution images just as smoothly as a single image. Photosynth collections typically have hundreds of photos, but the same performance characteristics apply to collections of 5,000 images and beyond.