ila mkuu usisahau kuwa umbali ambao satellite ipo kutoka hapa duniani ni km 36,000!....Mimi napinga kuwa zile picha huwa zinapigwa kwa satellite unless uweka reference hapa!
Google Earth - How They Do It!
A look at how Google Earth puts together images from all over the world.
By
James Lewis December 17, 2008
When you launch GoogleEarth on your computer, you start in outer space and you miraculously zoom in. You might see two unsuspecting guys walking across the Blue Wonder Bridge way off in Dresden, Germany.
But the folks at Google Earth remind us that you're not zooming in on just one picture. You're actually going through a succession - seamlessly - of closer and closer shots, making the transition from a NASA shuttle shot to a satellite shot to a photograph made from an airplane. So that's how they get such good close-up resolution.
Google doesn't shoot its own images. There are a handful of companies that do that. As you zoom in, down at the bottom of your screen you'll see names like AeroWest, DigitalGlobe, GeoContent, Cnes/Spot Image, NASA and Terra Metrics. Those are the various suppliers of images. But GoogleEarth has designed software that knits it all together so it feels like we're zooming in.
The primary source of GoogleEarth images is, DigitalGlobe. They told Pop Photo how the system works.
At the heart of it all is a satellite in a low orbit, going from one pole to the other. It's different from geostationary communications satellites because it's at 20,000 miles and always above the equator. You can't get a decent shot from that height. And the angle is limiting. For example, you'd always get a shot of the Statue of Liberty's front profile since she faces southeast. You'd never get a straight-down shot. The only alternative is to use a camera inside a satellite that's swooping from pole to pole at a much lower altitude, typically about 300 miles.
Chuck Herring at DigitalGlobe says they have two satellites to choose from, with a third launching next year. But the one they use the most, named QuickBird, makes a polar orbit every 90 minutes.
Google Earth - How They Do It!