Howtosignalprocessing
How does Google get 3D buildings?
Satellites collect 2D imagery, which is laid around the globe like an orange peel. The 3D imagery, however, is gathered via airplane, similar to how Google Street View cars grab photos from the ground. The images are overlapped, pieced together to show depth, and covered with texture.
Why are some places 3D in Google Earth?
The 3D imagery is aerial imagery from specially equipped planes. Google doesn't say why any particular places has been flown or not. The flights require multiple passes in clear weather and government permission to fly.
