We recently came across the YouTube video below about Google Earth’s 3D imagery. It gives some insight into how it is gathered and we also get to see some of the faces behind Google Earth, such as Google Earth Product Manager Gopal Shah.
Apparently the aircraft used to gather the 3D imagery use five cameras, one facing down then four others pointed in different directions. The ‘stereo’ imagery is not actually achieved by two cameras taking photos from different angles, but rather each single camera taking multiple photos as the aircraft is moving, effectively achieving a stereo effect. Previous analysis we have done (1 2 ) suggests that each camera captures four images in quick succession to get the ‘stereo’ effect for any given location and then imagery from multiple passes from different sides of the location are combined to create the final 3D.
Also interesting is that Gopal seems to imply that cars are manually removed from the imagery rather than via an automated process. Not mentioned in the video is the fact that Google pays special attention to some structures like bridges, harbour cranes and certain intricate buildings, using more manual methods. We believe the manual part of the process is the main reason 3D imagery often takes a long time between when the images were captured and when they are published in Google Earth.
It must also be pointed out that Google is continually improving the process and the latest releases of 3D imagery are significantly better quality than the oldest 3D imagery.