Avirtual globe is athree-dimensional (3D)software model or representation ofEarth or another world. A virtual globe provides the user with the ability to freely move around in the virtual environment by changing the viewing angle and position. Compared to a conventionalglobe, virtual globes have the additional capability of representing many different views of thesurface of Earth.[1] These views may be of geographical features, man-made features such asroads andbuildings, or abstract representations of demographic quantities such as population.
In 1993 the first version ofTerravision was released,[2] and in 1994 Art+COM presented it in theITU Plenipotentiary Conference of Kyoto.[3] Microsoft released an offline virtual globe on November 20, 1997, in the form ofEncarta Virtual Globe 98, followed byCosmi's3D World Atlas in 1999. The first widely publicized online virtual globes wereNASA WorldWind (released in mid-2004) andGoogle Earth (mid-2005).
Virtual globes may be used for study or navigation (by connecting to aGPS device) and their design varies considerably according to their purpose. Those wishing to portray a visually accurate representation of the Earth often use satellite image servers and are capable not only of rotation but also zooming and sometimes horizon tilting. Very often such virtual globes aim to provide as true a representation of the world as is possible, with worldwide coverage up to a very detailed level. When this is the case, the interface often has the option of providing simplified graphical overlays to highlight man-made features, since these are not necessarily obvious from a photographic aerial view. The other issue raised by such detail available is that of security, with some governments having raised concerns about the ease of access to detailed views of sensitive locations such as airports and military bases.
Another type of virtual globe exists whose aim is not the accurate representation of the planet, but instead a simplified graphical depiction. Most early computerized atlases were of this type and, while displaying less detail, these simplified interfaces are still widespread since they are faster to use because of the reduced graphics content and the speed with which the user can understand the display.
As more and more high-resolutionsatellite imagery andaerial photography become accessible for free, many of the latest online virtual globes are built to fetch and display these images. They include:
As well as the availability of satellite imagery, online public domain factual databases such as theCIA World Factbook have been incorporated into virtual globes.
In 1993 the German company ART+COM developed a first interactive Virtual globe, the project Terravision; supported by theDeutsche Post as a "networked virtual representation of the Earth based on satellite images, aerial shots, altitude data and architectural data".[2]
The use of virtual globe software was widely popularized by (and may have been first described in)Neal Stephenson's famousscience fictionnovelSnow Crash. In themetaverse inSnow Crash, there is a piece of software called Earth made by the Central Intelligence Corporation (CIC). The CIC uses their virtual globe as auser interface for keeping track of all their geospatial data, including maps, architectural plans, weather data, and data from real-time satellite surveillance.
Virtual globes (along with allhypermedia andvirtual reality software) are distant descendants of theAspen Movie Map project, which pioneered the concept of using computers to simulate distant physical environments (though the Movie Map's scope was limited to the city ofAspen, Colorado).
Many of the functions of virtual globes were envisioned byBuckminster Fuller who in 1962 envisioned the creation of aGeoscope that would be a giant globe connected by computers to various databases. This would be used as an educational tool to display large scale global patterns related to topics such as economics, geology, natural resource use, etc.[4]
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