Getting to Know Google Earth
Google Earth is a virtual globe program that was originally called Earth Viewer and was created by Keyhole,
Inc. It maps the earth by the superimposition of images obtained from satellite imagery, aerial photography and
GIS 3D globe. It is available under three different licenses: Google Earth, a free version with limited
functionality; Google Earth Plus ($20 per year), which includes additional features; and Google Earth Pro ($400
per year), which is intended for commercial use.
Overview from Wikipedia: http://en.wikipedia.org/wiki/Google_Earth
Formerly known as Earth Viewer, Google Earth was developed by Keyhole, Inc., a company acquired by
Google in 2004. The product, renamed Google Earth in 2005, is currently available for use on personal
computers running Microsoft Windows 2000, XP, or Vista, Mac OS X 10.3.9 and above, Linux (released on
June 12, 2006), and FreeBSD. In addition to releasing an updated Keyhole based client, Google also added
the imagery from the Earth database to their web based mapping software. The release of Google Earth
caused a more than tenfold increase in media coverage on virtual globes between 2005 and 2006, driving
public interest in geospatial technologies and applications.
The viewer displays houses, the color of cars, and even the shadows of people and street signs. The degree of
resolution available is based somewhat on the points of interest, but most land (except for some islands) is
covered in at least 15 meters of resolution. Las Vegas, Nevada and Cambridge, Massachusetts include
examples of the highest resolution, at 15 cm (6 inches). Google Earth allows users to search for addresses (for
some countries only), enter coordinates, or simply use the mouse to browse to a location.
Google Earth also has digital elevation model (DEM) data collected by NASA's Shuttle Radar Topography
Mission. This means one can view the Grand Canyon or Mount Everest in three dimensions, instead of 2D like
other map programs/sites. Since November 2006, the 3D views of many mountains, including Mount Everest,
have been improved by the use of supplementary DEM data to fill the gaps in SRTM coverage.
Many people using the applications are adding their own data and making them available through various
sources, such as the BBS or blogs mentioned in the link section below. Google Earth is able to show all kinds
of images overlaid on the surface of the earth and is also a Web Map Service client. Google Earth supports
managing three-dimensional Geospatial data through Keyhole Markup Language (KML).
Google Earth has the capability to show 3D buildings and structures (such as bridges), which consist of users'
submissions using SketchUp, a 3D modeling program. In prior versions of Google Earth (before Version 4), 3D
buildings were limited to a few cities, and had poorer rendering with no textures. Many buildings and structures
from around the world now have detailed 3D structures; including (but not limited to) those in the United States,
Canada, Ireland, India, Japan, United Kingdom, Germany, Pakistan and the cities, Amsterdam and
Alexandria. In August 2007, Hamburg became the first city entirely shown in 3D, including textures such as
facades. Three-dimensional renderings are available for certain buildings and structures around the world via
Google's 3D Warehouse and other websites.
In version 4.2, released August 22, 2007, Google Earth added a Sky tool for viewing stars and astronomical
images. Google Sky is produced by Google through a partnership with the Space Telescope Science
Institute in Baltimore, the science operations center for Hubble. Dr. Alberto Conti and his co-developer Dr.
Carol Christian of the Space Telescope Science Institute, plan to add the public images from 2007, as well
as color images of all of the archived data from Hubble's Advanced Camera for Surveys. Newly released
Hubble pictures will be added to the Google Sky program as soon as they are issued. New features such as
multi-wavelength data, positions of major satellites and their orbits as well as educational resources will be
provided to the Google Earth community and also through Christian and Conti's website for Sky. Also visible
on Sky mode are constellations, stars, galaxies and animations depicting the planets in their orbits. A real-time
Google Sky mashup of recent astronomical transients, using the VOEvent protocol, is being provided by the
Wikipedia and Panoramio integration
In December 2006 Google Earth added a new layer called "Geographic Web" that includes integration with
Wikipedia and Panoramio. In Wikipedia, entries are scraped for coordinates via the Coord templates. If the
options to show Wikipedia or Panoramio entries are selected, users will be presented with clickable dots in
their current Google Earth view. When any of these dots are selected, the user will be shown the Wikipedia or
Panoramio entry right in Google Earth. There is also a community-layer from the project Wikipedia-World.
More coordinates are used, different types are in the display and different languages are supported than the
built-in Wikipedia layer. See: *dynamic resp. static layer. Google announced on May 30, 2007 that it is
This article discussed Google earth and the website provides links to resources, Google navigation
guides, and data sets.
Teaching Geoscience with Visualizations: Using Images, Animations, and
Models Effectively Google Earth and Geoscience Education
Peter Selkin, University of Washington, Tacoma
Introduction: What is Google Earth
Google Earth is a virtual globe browser, arguably the most popular of those available for free on the
Internet (NASA's World Wind and ESRI's upcoming ArcGIS Explorer are competitors). Virtual globes allow
users to interactively display and investigate geographic data (primarily satellite and aerial images and
terrain models, but also 2- and 3-D vector data such as earthquake locations, water bodies, and
buildings). One of the most useful aspects of Google Earth from a geoscience education point of view is
the availability of a variety of geoscience-related datasets for free on the web.
Google Earth allows users to perform some basic measurements (latitude and longitude, elevation, and
size), which has led some users to consider it a variety of GIS software. Geoscience professors should be
careful when making this comparison. Alan Glennon, a graduate student in geography at UCSB, wrote two
essays on the pros and cons of so-called "naive" GIS (mainly focusing on applications such as Google
Earth). The essays (and the comments on them by other geographers) are a good starting point if you are
trying to decide whether to use a virtual globe such as Google Earth or a full-featured GIS such as ArcGIS
or GRASS in the classroom.
How to Obtain a Copy
The Google Earth browser is a separate application from your web browser. As of July 16, 2006,
the current stable version (v.3) runs on both Windows 2000/XP and Mac OSX (10.3.9 and higher).
A beta version (v.4) runs on Windows, Mac OSX, and Linux platforms. The Google Earth browser
can be downloaded from http://earth.google.com/.
Several upgrades to the Google Earth software are available. This discussion covers the standard
version (available for free for personal or educational use).
Using Google Earth
Getting Around in Google Earth: Common Functions
Navigation in Google Earth will be fairly intuitive for students who have grown up in an age of
clicking and dragging, mouse wheels, and video games. Those who are not familiar with the
interface may wish to take a look at one of the guides in the text box below. These guides describe
the basics of browsing in Google Earth better than I can. Nonetheles, I will summarize some of the
Google Earth allows the user to view true-color images draped over topography for most of the
globe, at varying resolutions mainly depending on the browser's "eye altitude" (height above
ground). The user can navigate (pan) either by clicking and dragging part of the field of view with
the mouse, by using the arrow keys, or by using a set of navigation arrows displayed in the main
Google Earth viewer window. The window's viewpoint can be rotated relative to the virtual globe
using a sliding or rotating control on the viewer window. The viewpoint can zoom into the globe
using a slider control, the mouse wheel (PC) or control-clicking and dragging (Mac). The viewpoint
can also "tilt" from a vertical position to a nearly horizontal poisition (again using a slider control).
Google Earth's main attraction, however, has been its ability to display vector datasets (placemarks
- points, lines, and polygonal areas), raster images (overlays), and 3D virtual models on top of the
virtual globe. Although some placemarks and overlays are supplied with Google Earth or are
directly accessible through Google Earth in the "Google Earth Community", the majority must be
downloaded from the Web. Placemarks and overlays are discussed in more detail later.
3D models of buildings in some cities are provided with Google Earth (the "Buildings" layer), but to
get the most use out of 3D models, you will have to download the SketchUp plugin. This will allow
you to build and use 3D objects in Google Earth. Although 3D models are fun to play with, they are
less broadly useful than other types of placemarks, so I won't go into them in detail. One clever
use of 3D models in an educational context, however - an exercise on visualizing wind farms - is
from Noel Jenkins' Juicy Geography site.
You and your students will probably find it useful to be able to measure features in Google Earth.
Here are a few hints on how to make a couple of different measurements:
Position: The latitude and longitude of the mouse pointer are shown in the status bar
near the bottom of the screen. An option in the Preferences dialog box allows you to
change whether position is displayed in degrees-minutes-seconds format or decimal
Elevation: The elevation of the mouse pointer is also listed at the bottom of the screen.
The "eye alt" value is the elevation of your viewpoint. An option in the Preferences
dialog box allows you to change whether elevation is displayed in feet or meters.
Distances: Google Earth allows you to measure the great circle distance from one point
to another or along a path (through several points), Distances are measured as the
crow flies, without taking topography into account (as far as I can tell). In Google Earth
3, the measurement tool is found under the "Tools" menu. In Google Earth 4, the
measurement icon appears as a ruler at the top of the window.
Vertical exaggeration can also be changed in the Preferences dialog box.
One final note about Google Earth navigation: The top panel on the left side of the Google
Earth window ("Search") allows the user to search for a location. In my experience, the
search function is not perfect: a search for Augustine Volcano, for example, returns no
results, and a search for "Mount Rainier" after a search for "Tacoma, WA" returns local
businesses with the word "Rainier" in their names. Latitude and longitude can be used
instead of a place name for less ambiguous searching.