Journey to the Center Of Google Earth.

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Author: Rubenking, Janet

Google Earth is a Windows client application that you download to your computer. At 10MB, the download is not very large, because all the images are streamed from the Internet as you navigate around the globe. You can get the program at earth.google.com. Before downloading the client, take a moment to read the FAQ, system requirements and important information about graphics card support. Bookmark this site because you'll want to return for information, including finding answers to your questions about the images. Google has posted a list of cities with high-resolution photos and the dates the pictures were taken.

To take advantage of this mesmerizing service, you need a good computer and a high-speed Internet connection for the intensive graphics. Minimum system requirements include a Pentium III 500-MHz system, 30 graphics with 16MB of VRAM. Windows 2000 or XP, 128MB of RAM, 200MB of hard drive space, and a 1,024-by-768, 32-bit true-color screen. A faster computer with more memory, hard drive space, and better graphics will deliver better images. Macs are not supported as of this writing.

When you load Google Earth, the viewer zooms in on our planet, shown against a starry background. The default screen display has panes for Search, Places, and Layers, and for a view screen to show you the virtual Earth. Below the view screen are navigation tools for tilting angles, zooming in and out, rotating clockwise or counterclockwise, and flying up, down, left, and right. You'll probably be tempted to search immediately for your house, community, or the neighborhood where you were raised. The client has an intuitive interface, so its basic operation requires little or no help. Enter an address or a place-name in Search and with a click of the mouse fly in and view satellite or aerial photo imagery stitched almost seamlessly together to form the Earth. Depending on the speed of your connection and the capabilities of your computer, the image resolves more or less quickly as it streams in from the Google servers.

Google Earth is fun, and the hours will speed by as you tour the world, but you'll get more out of your experience if you tweak your settings. To optimize its performance, go to Tools\Options, where there are tabs for View. Cache, Control, Navigation, and Preferences. Under Cache, enable a large disk cache â€" 5i2MB for computers that can support it. Memory cache should be set at half the amount of RAM you have on your system: don't worry if the program wants to reset it automatically to a smaller RAM cache.

Next, select View and configure the Area Detail (the area of focus for your images), to the smallest size acceptable to your taste. Medium is the default, and a large Area Detail is recommended only for computers that have a minimum 32MB of graphics card memory. Images load faster with a smaller view area, but the edges of the image will be blurry. A bit of experimentation is in order here. You can set font, label and icon size, compass, latitude and longitude, and elevation. Although label and icon size can be left alone for now, you may wish to select Small as you add layers, placemarks, and overlays. Return to the Options menu later as you gain experience with the service.

Several kinds of searches are possible with Google Earth. In the Search pane, the Fly To tab is enabled by default; entering a full address, or city and state, country, ZIP code, or even a latitude and longitude should take you there. Street address searches are limited to the U.S., the U.K., and Canada. Finding specific landmarks and buildings can be more of a problem. A search on Ayers Rock, or Ayers Rock, Australia returns nothing. To find this outback monolith, as well as many other landmarks, you need to search the Keyhole BBS, which we'll discuss later.

From the Local Search tab, you can find the locations and phone numbers for drugstores, gas stations, hardware stores, motels, and the like for a given community. Searching (as with Google searches in general) can be a fine art: Entering Coffee Shop returns exclusively Dunkin' Donuts outlets, but Coffee House gives a more diverse selection, and Diner a completely different set.

From the Directions tab, you can plot a route between two places, including roads to take and turns to make; the route will appear in purple on the globe. Pressing the Play Tour button at the lower right corner of the Search pane lets you follow the route. Tour speed, camera angle, and range are set through the Control tab using the advanced settings in the Options menu.

You can save your Google Earth searches by dragging a folder of results from the Search pane down to My Places.

Google Earth comes with a selection of layers to show features such as schools, roads, borders, and commercial services. Checkmarking layers in the Layers pane turns them on, but add them sparingly; too many will crowd the landscape in zoomed-out views. Experiment with 3D buildings and tilt the view angle to scan skylines. This feature is available for various large (mostly American) cities. Finally, checkmark the Terrain layer to have the program render mountains and valleys. Change the Elevation Exaggeration setting in the Options menu's View tab to sec dramatic views of geographical features such as the Grand Canyon.

Look at Africa for a great example of the use of layers. When the layer named National Geographic Magazine is checked, you will see a number of yellow frames and red airplane icons spread across the continent. Clicking on a yellow frame zooms in on a place, then takes you to a photo and links to material from a National Geographic article about that place. National Geographic has recently added such links to every article it has published about Africa and plans to extend this coverage to the rest of the world. The airplane icons link to photos (with 1-meter resolution) from J. Michael Fay's "Africa Megaflyover," from the September 2005 National Geographic.

Within days of Hurricane Katrina's assault on the Gulf Coast, Google Earth-in cooperation with NASA, NOAA (the National Oceanic and Atmospheric Administration), and Carnegie Mellon University â€" made available to the public overlays of thousands of images showing the effects of Hurricane Katrina on New Orleans and the rest of the region (see earth.google.com/hurricane.html). This data was used by relief workers and by evacuees trying to determine the condition of their homes and communities.

An essential layer to add is the Keyhole Community BBS (though if it clutters the landscape you may want to turn it off at times). It was established in support of the Keyhole software that Google acquired, renamed, and enhanced as Google Earth. You can access the Keyhole BBS (also known as the Google Earth Community) Web site through the Help menu or at bbs.keyhole.com/entrance.php?Cat=0. Spend some time there to find locations to visit, to read the posts, and to contribute to the community.

Saving places and sharing them with friends and networked communities can enrich everyone's Google Earth experience. For example, among the Keyhole BBS place-marks that we came across in central New Jersey are ones with descriptions and links that revealed the story behind a rusting ferry that had long intrigued one of our editors, the site of the Hindenberg Disaster and the location of the remains of that airship in Lakehurst, and the location of the Martian invasion (Grover's Mill) from Orson Welles's notorious 1938 radio broadcast of The War of the Worlds.

As the name implies, placemarks are locations on the globe that are marked with icons so that you can easily return to them. You can save your own searches and favorite places or add placemarks from other sources. Set the properties for the placemarks you create, including the name, icon, description (which can include HTML), style, location, and view. Later you can edit the placemarks to change properties.

Print your images or send them by e-mail as KMZ or JPEG file attachments. KMZ is a compressed KML (Keyhole Markup Language) file that will open as a placemark in the Google Earth client. Select a collection of placemarks in My Places and press the Play Tour button at the lower right corner of the Places pane in order to fly from place to place. You may need to experiment with the duration of the tour pause under advanced settings in Options so that images can resolve before the tour takes off for another location.

Managing your placemarks is as important as managing any other files. Once you start to accumulate favorite places and add those from friends and Web sites, you should put them in order and file them within your My Places folder for easy searching. And before you shut down the client, be sure to save any placemarks that are in your Temporary Places folder to a more permanent location, or you will lose them.

All images on the Google Earth globe are overlays. The satellite and aerial photos are always present, but you can add your own graphics on top â€" for example, a map of hiking trails, bus routes, or real-time satellite weather images. These extra images can be turned on and off at will, just like placemarks and layers.

To create an overlay, you need an image file with a BMP, GIF, JPG, PNG, TGA, or TIFF extension. PNG files often work best because they natively support transparencies, letting the underlying image show through. But any image that you add to an overlay can for transparency, and you can change the degree of transparency with a slide control.

Position the viewer in the orientation and elevation matching the overlay you are making. Select Image Overlay from the Add menu and enter a description in the name field. An overlay will completely integrate with the terrain or shape of the land beneath if the Terrain layer is turned on. Enter the location of the file on your computer, network, or the URL of the image on the Internet (right-click on the image, select Copy Image Location, and then paste).

At this point the overlay will appear in the viewer, and then you can orient it as you wish. Indicate the folder in which to save the overlay and give it an appropriate filename. If your image updates periodically, as a webcam or real-time weather posting does, set the refresh period. Finally, set the transparency and select OK. Additional adjustments may be necessary, and you can edit the overlay at a later date.

Overlays are popular with TV and Internet news sites. Many appeared in the aftermath of the London train bombings in July. Overlays will appear in My Places, with an icon showing map layers.

By now you should be seeing the bigger picture with Google Earth, but you might not want to do all the exploration on your own. Finding the Pyramids of Giza, Red Square in Moscow, or the Viaduc de Millau in France (the world's tallest car-accessible bridge), is time-consuming. Sometimes low-resolution images make it impossible. The Google Earth/Keyhole BBS is a great first stop to mine for placemarks and links to other geo activities. Members have posted tens of thousands of saved places from their wanderings; written overlays for the geocaching at www.geocaching.com, the official Global Positioning System (GPS) cache hunt site; and provided placemarks with links to other geographical imaging sites, such as the World Wide Panorama (geoimages.berkeley.edu/wwp/index.html). Another rich site for placemarks is Google Sightseeing at www.googlesightseeing.com, a Web site initially set up to post interesting finds using Google Maps satellite images, such as possible UFOs in Florida.

When you find a link that seems interesting, click on it and select Open to import the KMZ or KML file into Google Earth. It will load in your Temporary Places, waiting for you to view it, and then save to My Places. If you want to be a good neighbor, share your placemarks with others. The Google Earth/Keyhole BBS has an excellent tutorial about how to post your links and some advice on how to participate on the forums.

On July 20, the 36th anniversary of the Apollo 11 moon landing. Google introduced Google Moon at moon.google.com. Click the different landing sites marked there, and be sure to zoom all the way in for a close-up view.

There is a lot you can do with the free Google Earth client, but for a $20 annual fee you can upgrade to the Plus client and get GPS support, drawing tools, better print resolution, and the ability to import spreadsheet data.

As time passes, we'll see better, more plentiful, and more up-to-date pictures of our beautiful orb. In the meantime, join the geographical mapping phenomenon to learn more about our world.

The folks at Google Sightseeing reveal their favorite finds. Plus, other online sources of aerial imagery. See go.pcmag.com/googleearth.

CONDUCTING A LOCAL SEARCH to find delis in New York City yields a handful of results. Try using more specific terms, such as Italian deli, Jewish deli, or greek deli for a more focused list.

USE DIRECTIONS to map a car journey. Not only does this feature mark your route in purple, it even indicates what turns to make.

CLICKING ON THE blue information icons in Beijing's Forbidden City takes you to Keyhole BBS posts on the various palaces, gates, and other places and lets you download placemarks.

THIS VIEW OF Mt. St. Helens in Washington is a good example of Google Earth's 3D imaging capabilities.

HERE'S AN EXAMPLE of a large overlay using an image of the moon (actually, it's from Google Moon), showing Apollo landing sites. The overlay is in effect "stretched" over the Earth's globe.

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By Janet Rubenking

Janet Rubenking is a freelance writer, graduate student, and radio enthusiast from Northern California.