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“Looking through its legs” A New Kind of Landscape Photography.

by Rohit Kumar

Introduction:

Satellites look directly down at the earth, which show flat and map-like topography, but only few satellite images give us a sense of the landscape. On September 10, 2015, WorldView-3 followed an unusual route. As it passed over the Pacific, it turned back and looked at the continent to the east i.e. Los Angeles, Mojave Desert, the Grand Canyon and the southern tip of Utah. This picture, angled southwest-northeast, captured a huge swath of the state of Colorado. The technique is described as “looking through its legs”. Previously this technique was applied to capture an image of Mount Fuji and Nepal.

                                                ©DigitalGlobe, Topography of the state of Colorado.

How it works:

The earth is rotating at 16,000 miles per hour. WorldView-3 satellite is orbiting at 17,000 miles per hour at an elevation of 400 miles, that means Earth is actually moving under the vision of WorldView-3, so the commands have to be super precise in all measurements to turn the image into something useful. WorldView-3 satellite has GPS, star trackers with two cameras pointed back, I.M.U (inertial measurement unit) which measure inertia, satellite angular rate, magnetic field movement etc. and gyroscope which use angular momentum to point the satellite.

DigitalGlobe programs the satellite to look at the stars which are behind the field of view and behind the Earth. DigitalGlobe cannot program such commands to satellite because the optics are so much different than the required operation. That means DigitalGlobe satellite looks at stars that aren’t actually visible from where the satellite’s position is, to capture the image.

                                                          ©DigitalGlobe, Leadville airport in the middle of the mountains.

Geomorphic and other features are easily identified through this technique, i.e. Black Canyon of the Gunnison, the resort town of Crested Butte, airport, rugged topography, lakes, mountains etc.

                                                                 ©DigitalGlobe, Crested Butte.

Summary:

DigitalGlobe has previously used this technique to capture Mount Fuji and Nepal after the devastating series of earthquakes. In this technique, WorldView-3 satellite comprises of stars with cameras pointed back, are employed to capture the image. These unique pictures can be easily applied by researchers and other agencies to monitor the different landscapes of the Earth.


SATPALDA is a privately owned company and a leading provider of satellite imagery and GeoSpatial services to the user community. Established in 2002, SATPALDA has successfully completed wide range of photogrammetric and Remote Sensing Projects.

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