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The imagery is spectacular as you swoop down: from the curvature of the earth and delineation of the continents and snow-capped mountain tops, to the outline of individual houses. Depending on the tree canopy and the resolution of your city's imagery, you can check to see if your car was parked in the driveway at the time the latest set of satellite images were shot.

Additional controls are provided to dynamically move, spin, rotate, and zoom. But these are not simply flat views. The tilt controls reveal accurate 3D topologies (mountains, valleys). It's like a "magic carpet" ride over a credible landscape.

Google Earth's database of (Keyhole-type) satellite imagery does not contain uniformly high-resolution data for all locations, but it covers most major metropolitan areas throughout the world in reasonably high-resolution photography.

This database can give you resolution anywhere from the nearest meter to the nearest 3 inches (8 centimeters) for a well mapped city like Cambridge, Massachusetts. The imagery is certainly not completely current and can be up to three years old for some places. But for most of an architect's needs, it is quite good.

This software needs little instruction. You can just open it up and explore. Be careful exactly when you first run it, however, because for the rest of your workday, you may not be able to tear yourself away from Google Earth!

Practical Applications

Layers of Information. In any view, you can turn on and off various layers of mapping information such as road names, political borders, parks, and lodging, airports, and golf courses. The display of this information is scale-appropriate.

3D Buildings. In the downtowns of many U.S. cities (38 at this writing, but the number is growing), you can, by turning on the "3D Buildings" layer, see block representations of the cityscape. Though impressive, note that uniquely shaped architecture such as San Francisco's Transamerica Building or Seattle's Space Needle is still rendered as simple block forms.

Image Overlays. You can place your own custom images — such as building views, schematic site plans, master plans — over a 3D view from Google Earth. You can control the transparency of this overlay, so that you can see both layers simultaneously.

Measuring. Under Tools, you can pick Measure and Line, click on any two points and obtain the distance ("as the crow flies") between them. Perhaps more usefully, you can pick Path, click on a series of points, and get the cumulative distance along the traversed route.

Business searching. Google Earth allows you to search for businesses in a specific area. You can type in "pizza in Seattle, Island Drive" in the "Fly To" box, hit enter and Google Earth will fly you to a viewpoint showing 10 search results closest to your desired street in Seattle.

Then, by double-clicking on the target icon, Google Earth will fly you down to the location and show you a pop-up window view with information about the business, such as address, phone number, and link to hours of operation, reviews, menus, and business Web site, if any. You can ask for directions, then click the "Play" (arrow) button and Google Earth will tilt down and fly you along the route.

Animated Tour. You can save key locations as "Placemarks" then select several of them and hit the play button to tour the selected locations.

Print or Save and e-Mail. Google Earth allows you to print, save, and e-mail images. You can send driving directions to a friend as a raster image or just send as a Placemark to another Google Earth user. You can hook-up with Google Local to get a traditional street map.

Architects can save images of sites for import into CAD drawings. With the less expensive versions of Google Earth, you are relegated to saving images at the displayed screen resolution. But under Options/ Tools/ View, you can increase the image size from the default 512x512 pixels to 1024x1024.

By turning off the other toolbars before you save an image, you can save quite sharp images for architectural use. You can also set various aspect ratios for display, playback, or printing in the View menu, under View Size.

Adding to the Database

You can now even integrate your own CAD models with Google Earth through SketchUp's "3D Warehouse." Download a plug-in for SketchUp 5, then export any SketchUp model to a KMZ file (zipped Google Earth information file).

Digital 3D models from most CAD software can be placed in Google Earth by loading a DXF file into the free version of SketchUp and then exporting in the Google Earth format. If done properly, the SketchUp model will display in Google Earth at its proper location, scale, and orientation.

Some other CAD companies have already written software to support export of models into Google Earth. These include Bentley Systems for MicroStation, Eyebeam for Maya, and Robert McNeel & Associates for Rhino. With RoboGeo, you can export "geocoded" photographs.

Google Earth has now arrived as a must-have tool for architects. If I haven't convinced you already, a short test-drive of this incredible software certainly will. And it won't cost you anything — except time — to tour the world!

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Evan H. Shu, FAIA is an architect with Shu Associates Inc. in Melrose, Massachusetts. He is a contributor to The Architect's Handbook of Professional Practice and is publisher and editor of Cheap Tricks, a monthly newsletter for DataCAD users and computer-using architects.

This article was reprinted from the March 2006 issue of Cheap Tricks © Shu Associates Inc. with permission of the publisher.

This detailed building model can be shown side-by-side with Google's 3D buildings because it is placed on a site that is a vacant lot in real life, so there is no Google geometry to interfere with it. Image: Courtesy Google/ Detailed building model (Daniel Burnham's Reliance Building) by Artifice, Inc. SUBSCRIPTION SAMPLE The Gateway Arch in St. Louis, Missouri, designed by Eero Saarinen, demonstrates how users can place 3D models, built with their own CAD software, into Google Earth. Image: Courtesy Google/ Gateway Arch model by Artifice, Inc. A refined model of the Gateway Arch is lost in the context of Google's blocky representation of 3D buildings. Currently in Google Earth, the 3D context buildings can either be all shown, or all turned off. Image: Courtesy Google/ Gateway Arch model by Artifice, Inc. Satellite image of Chicago, with a layer of place names overlaid. Image: Courtesy Google Bird's eye perspective of Chicago, showing 3D buildings. Image: Courtesy Google Satellite image of Rome, with "Placemarks" indicating that additional information is available. Image: Courtesy Google Google Earth measures the distance "as the crow flies" between two points in Rome. Image: Courtesy Google Google Earth measures the walking distance between two points in Rome. Image: Courtesy Google   Click on thumbnail images to view full-size pictures.