Using Google Earth for fun and functionality

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					            Using Google Earth for fun
                and functionality

                                                   — By Douglas Vandegraft
                                                    CaGIS Immediate Past President

                                                                                                                                               start-up view

       “It is often essential to view information in a spatial context in order to aid in understanding.”
       — Rebecca Moore, Software Engineer, Google Earth

Google Earth                           is a free
internet tool that has opened the eyes of mil-
                                                   Earth’s popularity with a growing number
                                                   of scientists (and federal agencies) lies
                                                   in the almost equal ease with which it
                                                                                                     Google Earth is one of the most popu-
                                                                                                  lar virtual globe applications; it has an
                                                                                                  audience of over 250 million regular
lions to the possibilities of digital geography.   lets them overlay their own spatial data       users. This is quite possibly the largest
In essense, it’s a“virtual globe” that allows      on top of the Google Earth background          audience for geospatial data in the world.
even the casual user to zoom from space            imagery.                                       When I first saw it live, it reminded me
right down to street level, with images that           Google Earth maps the surface of the       of the “ArcGlobe” demonstrations that
in some places are sharp enough to show            Earth by superimposing images from satel-      I had seen at the ESRI (Environmental
individual people. Besides viewing any             lites and aerial photography. It depicts the   Systems Research Institute Inc.) confer-
place on Earth, viewers can go on a “tour          Earth as if you were looking at it from an     ences I have been to. Once installed, I
of the world,” get driving directions from         airplane or orbiting satellite. Google Earth   found Google Earth very easy to use, and
one place to another and fly (follow) the          can be downloaded for use on personal          I confess to hours of viewing places I’ve
route, view the terrain of a place in 3D,          computers running Microsoft Windows            seen in real life and places I hope to see
and view locations and features created                     ,
                                                   2000, XP or Vista; Mac OS X 10.3.9 and         in the future. In my opinion, Google Earth
by other Google Earth users. Google                above; Linux; and FreeBSD.                     is the virtual globe program that the ESRI

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                                                                                                               Google Earth

people hoped ArcGlobe could have been.      uses a “General Perspective” projection,        (which for a $20 annual subscription
The ease of use and functionality make it   which is similar to an orthographic pro-        fee includes features such as GPS inte-
a useful tool for novice geographers as     jection, except that the point of perspec-      gration, higher resolution, and customer
well as professional cartographers and      tive is a finite (near Earth) distance rather   support via e-mail), and Google Earth Pro,
surveyors.                                  than an infinite (deep space) distance.         which for a $400 annual fee has all the

                            The City of Unalaska and the International Port of Dutch Harbor, Alaska

Facts and features                             Google Earth works with two- and             features of GE Plus including a GIS data
Google Earth was developed by Keyhole,      three-dimensional data, vector data, and        importer, a tool for making movies and
Inc. and was initially known as “Earth      a variety of geometric projections. The         advanced printing modules.
Viewer.” Google acquired Keyhole in 2004    variety of imagery sources requires that
and renamed the product Google Earth. It    the processing be done by both machine          Resolution and accuracy
was formally launched in June of 2005.      and humans. This results in a certain           Most land areas, except for islands, are
   The internal coordinate system uses      amount of inaccuracy.                           shown using satellite imagery with a
geographic coordinates (latitude/longi-        The product is available under three         resolution of about 15 meters per pixel
tude) on the WGS 84 (World Geodetic         different licenses: a free version with         or better. The 15-meter accuracy is the
System of 1984) datum. Google Earth         limited functionality; Google Earth Plus,       baseline for most areas of the application.

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 Some urban areas in the U.S., notably Las scale legend, and the atmosphere, which include viewing intense geography such as
 Vegas, NV, Cambridge, MA, and the Google gives off a blue halo effect.                     the Grand Canyon and Mount Everest, and
 Campus in Glendale, CA, can be viewed at          Also in “View” is the Tool Bar. Along flying through downtown Manhattan!
 1 meter and even 0.15 meter resolutions. with the usual print option and to view/            The sidebar on the left is divided into
 This is because ortho-photography, with hide the sidebar, you can access the ruler three categories: Search, Places, and
 several pixels per meter, was used in the tool for measuring distances between Layers. The Search tab prompts the
 tiling. You can literally read street signs and places, and a “Placemark” tool for saving viewer to “Fly To” a destination of their
 see individuals in these areas.                 specific locales. More functionality is choice. You can also “Find Businesses”
     The other extreme is at places such offered with the “Add Polygon,” “Add or get driving “Directions” similar to the
 as the poles: the Antarctic continent is Path” (for adding a line or lines) and the Google Maps application. I had a chuckle
 reflected at very low resolution, with a “Add Image Overlay” tools.                        when I asked for directions from New
 few exceptions, and the Arctic polar ice          The “Tools” offered on the drop-down York City to Paris, France. After directing
 caps are not shown at all.                      menu include opening a web browser, a me from NYC to Boston, I was instructed
     Other ocean areas fall into
 this same category. The geo-
 graphic North Pole is found
 floating in the Arctic Ocean,
 and it appears as the center
 of a blue kaleidoscope made-
 up of the converging tiles.
     The Northwest Hawaiian
 Islands are shown using high-
 resolution IKONOS imagery;
 never mind that some features
 are incorrectly labeled as the
“Midway Islands.”
     Most of the Aleutian Islands
 of Alaska, surprisingly, were
 captured on some almost
 cloud-free days. Google con-
 tinues to resolve inaccuracies
 in the vector mapping, and
 frequently updates the typi-
 cally three-year-old imagery.                                    The South Pole as seen on Google Earth

Ease of use
When you launch the Google Earth              second access to the ruler, and the GPS to “Swim across the Atlantic Ocean
Home Page, you are presented with a           integrator (functions only on GE Plus).      entering France” with a distance esti-
view of the North American continent             The “Play Tour” tool will fly to the mated at 3,462 miles.
as it appears from space. (The stars that     selections checked on your “My Places”         The “Places” tab is where you store
appear in the background aren’t just for      list, and the “Options” tab brings up a all of your favorite destinations. It’s also
decoration; they were taken from astro-       whole suite of possibilities. These are where you store any imported data.
nomical charts and approximate their          mostly for customizing your “3-D View,”
actual position.) If you click on “View” at   the memory cache, the speed of your Available layers
the top, you are given options to display     flying and driving tours, and the speed of The “Layers” tab presents many different
a compass and a latitude/longitude grid.      your mouse wheel.                            data sets that you can add to the viewer.
   When one selects the “Status Bar,”            In the upper right corner are the “Navi- The number of available layers seemingly
the latitude and longitude of the pointer     gation” controls. If your mouse doesn’t increases every time I visit Google Earth.
is tracked and displayed in the lower         have a roller-ball, this is where you can      The expected layers include roads,
left corner, and the “Eye altitude” is dis-   elect to rotate the view as well as “tilt” populated places, transportation, as well
played in the lower right. You can also       to view the terrain or buildings that are in as dining, lodging, shopping, and travel
display an overview map of the world, a       3-D. Fun things to do with the tilt option and tourism. But you can also view Con-

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                                                                                                                  Google Earth

         Using the ruler tool to measure the distance between Honolulu, Hawaii, and Rose Atoll National Wildlife Refuge
                                                       in American Samoa

 gressional Districts, Postal Code bound-       New layers                                      KML and Google Earth
 aries, and City boundaries. You can also       Recently, the National Park Service and         As a long-time user of the ESRI ArcGIS
 view indexes of imagery collected by           the U.S. Forest Service were successful         suite of products, I was excited to learn
 DigitalGlobe between 2002 and 2007.            in contributing their spatial data to Google    that an enterprising GIS Specialist work-
    Under the “Primary Database” are            Earth. They are found under the “Parks and      ing for the City of Portland, Oregon, had
“Featured Content” providers such as            Recreation” layer tab. When the National        written a program to convert ESRI shape-
 National Geographic, Discovery Net-            Park or National Forest layer is made active,   files to the KML format. This program,
 works, American Institute of Architects,       users can click on a park or forest on the      Export to KML, can be downloaded from
 Trimble Outdoors Trips, Yelp Reviews of        globe (or zoom to it) and view a pop-up         the ESRI website (http://arcscripts.esri.
 restaurants, Tracks4Africa, the European       window showing a postcard-like photo-           com/details.asp?dbid=14273), and it is
 Space Agency, and my personal favorite,        graph and a brief description of the park or    installed as a tool in the ArcMap applica-
 the Rumsey Historical Maps.                    forest, including a link to the corresponding   tion.
    Under the “Global Awareness” cat-           website. Similar efforts are also underway        I converted the boundaries of all 547
 egory can be found spatial data reflect-       with the Natural Resources Conservation         National Wildlife Refuges to the KML
 ing the crisis in Darfur, the World Wildlife   Service, the Bureau of Land Management,         format and was delighted with the result.
 Federation Conservation Project, and           and (hopefully!) the U.S, Fish and Wildlife     Using Google Earth, I am able to quickly
 Jane Goodall’s Gombe Chimpanzee Blog.          Service to display their spatial data.          view the geography within and surround-

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                           A historical map from the Rumsey Collection draped over the Google Earth globe

ing the wildlife refuges, and have put it to practical use. For refuge names) being seen all over North America. This issue is
example, I examined the shorelines of our 174 coastal refuges alleviated as soon as I start to zoom in, as the refuge polygons
to see which of these contain waterways that were potentially soon become much larger than the text.
tidally influenced; viewed existing dams at the Balcones Can-
yonlands refuge in Texas; used the ruler tool to quickly derive Virtual Globe mania
miles of refuge boundaries that straddle the US-Mexico border, More virtual globe applications are appearing that mimic the Google
and to quickly calculate the distance from major cities to some Earth environment to some extent. MSN Virtual Earth, Leica Virtual
of our remote refuges (Rose Atoll NWR is 2,559 miles from Explorer, NASA World Wind, and ArcGIS Online (the supposed
Honolulu, where the administration office is located).           “Google Earth killer”) are all unique for some of their additional data.
    While importing this much additional data into Google Earth, NASA World Wind, for example, has extraterrestrial data sets such
I’ve discovered a few hitches. 1) Loading 547 additional KML as Mars, Venus and Jupiter. ArcGIS Online has maps and globes to
files on Google Earth increases the time it takes to launch. 2) import into specific mapping projects. I look forward to trying all of
The Export to KML program converts the name of the refuge these virtual globes. I fully expect that the functionality will improve,
(stored as an attribute in the shapefile) to text which hovers and the cost to drop, as the public becomes more aware of their
over the refuge polygons, resulting in many lines of text (the potential to educate and improve our everyday life.

ArcGIS Explorer                                                            currently in beta. ArcGIS Online gives you access to high-resolution
This unique application lets you connect directly to a variety of ready-   premium imagery at no cost and includes a seamless mosaic of 1
to-use globes hosted by ESRI and extend the power of web-based             m resolution aerial imagery for the contiguous United States and
services by fusing them with your local data. Says Bern Szukalski,         satellite imagery for the world at 500 m and 15 m resolutions. The
ArcGIS Explorer product manager, “You can unlock the power of GIS          high-resolution imagery is a color mosaic of recent commercial
for others when you author your own content and tasks and deliver          imagery for metropolitan areas and best available government
access to these using ArcGIS Explorer. With this free application,         imagery for other areas. At the end of the ArcGIS Online beta
you can publish ArcGIS Server capabilities within your organization        program, ArcGIS users will be able to subscribe to the premium
or to anyone on the web.” On startup of the free download, ArcGIS          high-resolution imagery service. Other basic data will continue to be
Explorer opens a satellite globe. In addition to imagery, you can          free. ArcGIS Explorer also includes a software developer kit (SDK)
access other free globes including worldwide streets, terrain,             that can be used to extend tasks or implement custom tasks that are
boundaries and labels, political maps, and physiography. These             driven by other web services. Download ArcGIS Explorer at www.esri.
globes are served to ArcGIS Explorer via ArcGIS Online, which is           com/arcgisexplorer.

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