Essentially they use a rig of DSLR cameras mounted to the bottom of a Cessna to take photographs in a 45 meter grid, and then do stereo reconstruction from that. Crucially they describe using fast phase based disparity maps, which at the time were a recently declassified technique for guiding cruise missiles. C3 was a part of the defense contractor Saab AB.
Saab also owns Vricon, basically the same thing as C3 but not aimed at consumers. They sold part of it to DigitalGlobe, and they use both aerial and satellite imagery for 3D models.
Nokia also invested in C3 and had the first 3D maps available to consumers before anyone, completely in WebGL which used to be on https://wego.here.com. I guess Apple had more money to acquire them.
https://9to5mac.com/2011/10/29/apple-acquired-mind-blowing-3...
The technique is detailed in the conference paper:
https://www.spiedigitallibrary.org/conference-proceedings-of...
Essentially they use a rig of DSLR cameras mounted to the bottom of a Cessna to take photographs in a 45 meter grid, and then do stereo reconstruction from that. Crucially they describe using fast phase based disparity maps, which at the time were a recently declassified technique for guiding cruise missiles. C3 was a part of the defense contractor Saab AB.