Geography Reference
In-Depth Information
close to meeting the vision sketched by US Vice-President Al Gore in a speech prepared for
delivery in early 1998:
Imagine, for example, a young child going to a Digital Earth exhibit at a local
museum. After donning a head-mounted display, she sees Earth as it appears from
space. Using a data glove, she zooms in, using higher and higher levels of resolution,
to see continents, then regions, countries, cities, and finally individual houses,
trees, and other natural and man-made objects. Having found an area of the
planet she is interested in exploring, she takes the equivalent of a 'magic carpet ride'
through a 3-D visualization of the terrain. (www.isde5.org/al gore speech.htm)
Google Earth's technology was far less sophisticated than Gore's Digital Earth, since it
could run on almost any home computer and did not require the museum's immersive
environment. However, it also fell somewhat short of the full vision, since the speech talks
of being able to explore Earth's history, and to visualize Earth futures as the outcomes of
simulation models.
The idea of a mirror world, an integrated representation of all that is known about the
planet, is much older than Gore's speech, and older than Gore's earlier and much less
developed reference in his 1992 topic
Earth in the Balance
(Gore, 1992). Humans have a
long history of Earth representation, from the earliest drawings on cave walls to the first
printed maps and the first images from space. Digital Earth represents the culmination of
a long process that includes the advances made in the digital representation of maps in the
1960s, the development of sophisticated three-dimensional graphics, the popularization of
the Internet in the 1990s, and the development of massive stores of digital geographic data
in the form of data warehouses and geoportals (Maguire and Longley, 2005).
The 2005 launch stimulated a vast number of activities. The release of an application
program interface (API) allowed more sophisticated users to add content to the service
using KML (Keyhole Markup Language), and Google Earth is now just one of a fam-
ily of
geobrowsers
that includes Microsoft's Virtual Earth (http://maps.live.com), ESRI's
ArcGIS Explorer (www.esri.com/software/arcgis/explorer/index.html) and NASA's open-
source World Wind (http://worldwind.arc.nasa.gov/). This chapter explores the significance
of geobrowsers for the social sciences, using Google Earth as its example. The next section
provides a brief review of the service and the technical challenges that it overcomes. This is
followed by a section on the fundamental spatial concepts that underlie the service, and that
should be understood by anyone seeking to make effective use of it. The following section
addresses issues of the social context of Google Earth that are of interest to academic social
scientists, and the final section addresses some of the challenges for the research community
that remain to be solved if future generations of geobrowsers are to go further in meeting
the needs of the social sciences.
2.2 Major features of Google Earth
2.2.1 Hierarchical tessellation
Paper maps must of necessity flatten the Earth, and over the past five centuries a highly
sophisticated technology of map projections has evolved (Grafarend and Krumm, 2006;
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