Satellite photography is a dramatic example of how computer graphics and remote imaging have changed the way we view our planet. How did it go from Cold War surveillance technology to something most of us have in our pocket?
From space to your face—a new view of Earth
Powers of Ten was a flip-book based on a film made by Charles and Ray Eames in 1968. The film—which zooms away from an overhead shot of a couple picnicking in a Chicago park out to distant galaxies, and then back into a carbon nucleus inside the man’s hand—was itself inspired by a flip-book called Cosmic View (1957) by Dutch educator Kees Boeke.
In the 1990s, a group of software engineers began to think about how to create digital maps from satellite photographs. Their aim was to knit together digital images at different scales so seamlessly that you could zoom from one magnification to another.
John Hanke, Mark Aubin and Brian McClendon worked for Silicon Graphics Inc, a Californian company specialising in 3D computer graphics. In order to advertise the lifelike textures of one of their products, a graphics processor running software called Clip Mapping, they decided to base a demonstration on the Powers of Ten flip-book.
The Silicon Graphics team’s ‘killer demo’ began in outer space and zoomed in to the Earth, coming to rest on their logo inside a Nintendo 64—placed on top of the Matterhorn in the Alps. This demo, which they called ‘From Space to Your Face’, was a sensation wherever they showed it.
The three engineers left Silicon Graphics and founded their own company, Keyhole, to develop an application that would allow users to zoom in to any location on Earth from above.
The origins of satellite photography
The US began a photo-reconnaissance satellite programme in 1959. Their satellites were known as KH-1 to KH-9—they were ‘keyholes’ that allowed their users to spy on territories that were off-limits to aircraft, such as military installations in the Soviet Union and China. When Hanke, Aubin and McClendon founded their company in 1999, they named it Keyhole in tribute to these satellites.
In 1972 NASA continued to survey the Earth with the launch of the first of a series of Landsat earth observation spacecraft. These collected photographic images and remote-sensing data from electromagnetic radiation bouncing back from Earth.
At first, the use of images from spy satellites was highly restricted, controlled by government agencies. Keyhole was formed just as these agencies began to recognise the commercial possibilities of digitised images and make them more widely available.
In 2001 Keyhole launched EarthViewer, which seamlessly combined images from satellites, aircraft and other sources to give a complete view of the Earth’s surface—though some images were clearer than others.
It also offered the ability to navigate the terrain as though in your own personal aircraft. EarthViewer was a consumer product which could run on a standard PC, but its high subscription price meant that only large organisations could take advantage of its features.
In 2003, EarthViewer reached a wider audience: images from the software were used by broadcasters all over the world in their reporting of the Iraq war.
What was different about Google Earth?
The internet search company Google immediately saw the appeal of EarthViewer to a wider market, and bought Keyhole in 2004. Members of the EarthViewer team continued to refine the product; it was relaunched as Google Earth the following year.
Like EarthViewer, Google Earth combined satellite images with aerial photography, collected in overlapping sweeps.
Digital graphics technology then fused the images, correcting the colour balance and warping where necessary to ensure that transitions from one image to another were undetectable.
The engineers then added data from many sources—local and national governments, commercial companies and international agencies—to fill in features such as national boundaries and the names of towns and streets.
Google Earth was free for anyone to download, and people were soon happily zooming across the world to look at holiday locations or relatives’ houses. Combined with mapping data, Google Earth allowed people to find their way almost anywhere in the world.
How has Google Earth been used?
One unexpected benefit of Google Earth has been its usefulness in helping people and areas affected by natural disasters.
In August 2005, Hurricane Katrina devastated the town of New Orleans in Louisiana when flood walls, designed to resist storm surges, failed catastrophically.
Emergency services needed to find stranded people quickly and assess how best to rescue them. They turned to the newly-released Google Earth. Google engineers were able to quickly update their database with the latest images, which greatly aided relief efforts.
Following this example, agency workers used Google Earth to search for survivors of earthquakes in Haiti in 2010 and Japan in 2011.
Urban development researchers have used Google Earth to map areas of inadequate housing, allowing them to more effectively plan future communities.
In the Brazilian Amazon, meanwhile, the Surui people have used it to map their homeland and record illegal logging.
These examples show how two relatively new developments—computer graphics and remote imaging—have dramatically changed the way we view our planet.
What impact has Google Earth had?
From 2007, Google began to add data collected at ground level to its maps. This allowed it to offer the Street View feature in many towns and cities around the world. Now people could virtually ‘walk’ through neighbourhoods as well as looking at them from above.
With the advent of smartphones, users on the move could access the power of the Google Earth database with just a few taps. Further developments enabled them to add and share their own photographs to locations. These features are now an essential part of everyday life for millions of users, helping people navigate unfamiliar areas, identify landmarks and find things to do.
There are more serious uses, too. Teachers of geography and environmental science are one market, helping students in the classroom to visualise the locations they are studying.
Technologies that were originally developed for defence and security are now also tools for global aid, democratic representation, and personal enjoyment.