Google Earth

Google Earth is a virtual globe that is available for free through the Internet to anyone in the world who has an Internet connection and a computer with the minimum requirements. Google Earth is many things in one: a virtual globe, a 3D (three-dimensional) geobrowser, an interactive geospatial encyclopedia, a basic GIS (geographic information system), an advanced visualization technology, and a tool for teaching, learning, and entertainment (Figure 1).

Google Earth was originally developed by Keyhole Corporation, which Google purchased in October 2004. In early 2005, the basic version of Google Earth became available to the public. Google Earth enables exploration of the terabytes of images and information served by Google within the spatial context of Earth. In addition to Earth, the software includes a virtual rendering of the sky, a bathymetry of the ocean floor, and a virtual globe of the planet Mars.

The Google Earth virtual globe is covered with layers of satellite and aerial imagery of Earth displayed at various resolutions and scales. In certain areas, multiple images acquired on different dates can be viewed sequentially. Google Earth provides the user with numerous layers of information related to the location being viewed that can be optionally shown, such as Web links to articles, high-resolution and panoramic ground-based photography, 3D models of terrain and buildings (Figure 2), weather, traffic, road and street names, 360° photography of street views, points of interest, information related to organizations, and many other features that are continuously updated by Google and the Google Earth community.

In Google Earth, one can search for geographic features using Google's search technology by simply entering the name of a geographic feature, an address, a place name, or a set of coordinates or by browsing with the mouse. The built-in DEM (digital elevation model) enables one to view the relief of mountains and valleys or dive below the surface of the ocean to observe the deep tranches and canyons (Figures 3 and 4). The user can fly over the terrain, pan, rotate, tilt, spin, or jump to another place on the globe.

Google Earth enables some basic functions of a GIS. Tools for measuring distances and areas and for creating lines and polygons that the user may save on his or her computer are all included. Users can also add their own information, which can be a place-mark, text, images, video, or links to other information on the Web. Users may also import GPS (global positioning system) data such as waypoints or tracks and create multiple layers of their own raster or vector data. Layers of information may be saved to files using the KML (Keyhole Markup Language) and shared with other users using Google Earth as a posting board (Figure 5). With or without the use of KML, Google Earth can be an effective learning experience. Google Earth provides a way to visualize complex geographic information to make it more easily understood by the general public.

Figure 1 Google Earth with the borderlines in yellow and the layers of information on the left

Source: Google Earth.

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