Virtual globe

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NASA World Wind, an open source virtual globe with stars and advanced atmosphere & sunlight effects
NASA World Wind, an open source virtual globe with stars and advanced atmosphere & sunlight effects
Microsoft Virtual Earth 3D within Live Search Maps site
Microsoft Virtual Earth 3D within Live Search Maps site

A virtual globe is a 3D software model or representation of the Earth or another world. The first widely publicized virtual globe was Google Earth. 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 conventional globe, virtual globes have the additional capability of representing many different views on the surface of the Earth. These views may be of geographical features, man-made features such as roads and buildings or abstract representations of demographic quantities such as population.

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[edit] Types

Virtual globes may be used for study or navigation (by connecting to a GPS 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.

[edit] Online virtual globes

As more and more high-resolution satellite imagery and aerial 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 the CIA world factbook have been incorporated into virtual globes.

[edit] Technical info, data and image sources

Although by default the World Wind download only comes with public domain imagery from the USGS and Landsat 7, Community members have made available high resolution imagery for New Zealand and New York, here and additional countries, as well as Microsoft's Virtual Earth data (for non-commercial purposes)

Google Earth, NASA World Wind and Norkart Virtual Globe save a cache of downloaded imagery to the user's hard disk, enabling them to be used offline to view previously viewed areas. However, you cannot activate Google Earth without logging into its server for the first time.

The Google Earth's cache size is limited to 2000 MB whereas World Wind has no limit on cache size. In Norkat Virtual Globe the disk cache can be set by the user.

In addition to downloaded images, NASA World Wind also comes with the complete 500 m Blue Marble imagery and global placenames including countries, capitals, counties, cities, towns and historical references which are available from install.

World Wind is also capable of displaying MODIS imagery from the JPL Aqua and Terra satellites. An Add-on allows for near-real-time MODIS imagery.

Google Earth and Virtual Earth 3D are both capable of displaying many more urban areas in high-resolution thanks to their private image sources. Both companies also hire chartered flights over major cities of the U.S. to take aerial images.

3D Weather Globe & Atlas comes with complete 1 km Blue Marble imagery, 40,000 locations database, countries and time zones overlays. Application requires internet connection only for online features: satellite cloud cover and real-time weather and forecast data.

[edit] History

The use of virtual globe software was widely popularized by (and may have been first described in) Neal Stephenson's famous science fiction novel Snow Crash. In the metaverse in Snow Crash there is a piece of software called Earth (just like Google's), made by the Central Intelligence Corporation. The CIC uses their virtual globe as a user 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 all hypermedia and virtual reality software) are distant descendants of the Aspen 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 of Aspen, Colorado).

[edit] Comparison

The 3 most popular of today's virtual globes can support various features:

virtual globe Introduction year OS - Windows, Mac, Linux, Unix Program/data license Multiple datasets Street map overlay School, Restaurant, and Hotel guides Transportation guides Park guides Satellite and aerial image overlay Weather map overlay Topographic map overlay Real-time traffic report GPS-integration Distance measure Drawing tools Movie maker
Google Earth 2005[1] yes, yes, yes, no freeware (Basic)
proprietary(Pro)		 No Yes Yes Yes Yes Yes Yes Some[2] Yes Yes[3] Yes Yes Yes[4]
NASA World Wind 2004[5] yes, no, no, no open source / free domain Yes No No Yes No Yes Yes Yes No Yes Yes No Yes[6]
Microsoft Windows Live Search Maps Virtual Earth 3D 2006[7] yes, no, no, no proprietary No Some[8] No Yes No Yes No No No No Yes No No
virtual globe Introduction year OS - Windows, Mac, Linux, Unix Program/data license Multiple datasets Street map overlay School, Restaurant, and Hotel guides Transportation guides Park guides Satellite and aerial image overlay Weather map overlay Topographic map overlay Real-time traffic report GPS-integration Distance measure Drawing tools Movie maker
virtual globe 3D graphics 3D building models Terrain models Sea-floor models Planetarium Day/night views Imagery of other planets Telescope/Sky mode Flight simulator Sunlight simulator Online community user input Extensibility Wikipedia integration
Google Earth Yes Yes Yes No Yes Yes Yes Yes[9] Yes Yes Yes Some[10] Yes
NASA World Wind Yes No[11] Yes Yes Yes Yes Yes Some[12] No No Yes Yes[13] Yes
Microsoft Windows Live Search Maps Virtual Earth 3D Yes Yes Yes No Yes No No No No No No No No
virtual globe 3D graphics 3D building models Terrain models Sea-floor models Planetarium Day/night views Imagery of other planets Telescope/Sky mode Flight simulator Sunlight simulator Online community user input Extensibility Wikipedia integration


virtual globe languages supported 3d buildings Hi-resolution data set areas street-level address search areas driving direction areas business listing areas hotel listing areas
Google Earth German, Dutch, English, Spanish, French, Italian, Japanese
(with Help support in Arabian, Czechian, Korean, Portuguese, Polish, Russian)		 Yes: United States, Germany, Italy, France, United Kingdom, Netherlands [14] Yes: Australia, Belgium, Canada, China, Denmark, France, Germany, Italy, Japan, Netherlands, Spain, United Kingdom, United States Yes: Australia, Belgium, Brazil, Canada, China, Czechia, Denmark, Estonia, France, Germany, Hungary, Italy, Japan, Lithuania, Netherlands, Poland, Spain, United Kingdom, United States Yes: Australia, Belgium, Canada, China, Denmark, France, Germany, Italia, Netherlands, Spain, United Kingdom, United States Yes: Australia, Belgium, Canada, China, Denmark, France, Germany, Italia, Japan, Netherlands, Spain, United Kingdom, United States Yes: Australia, Belgium, Canada, China, Denmark, France, Germany, Italia, Japan, Netherlands, Spain, United Kingdom, United States
NASA World Wind English No Some: United States, New Zealand (partially) Some: Australia, Germany, France, Japan, United States, United Kingdom[15] No No No
Microsoft Windows Live Search Maps Virtual Earth 3D English Yes Some: United States, Canada, United Kingdom, Italy, France, Australia, Germany Some: United States, United Kingdom, Australia Some: United States, United Kingdom, Australia[16] No No
virtual globe language support 3d buildings Hi-resolution data set areas street-level address search areas driving direction areas business listing areas hotel listing areas

[edit] See also

Atlas Portal

[edit] References

  1. ^ Google Press Center: June 28, 2005 - Google announced the launch of Google Earth
  2. ^ GE offers a few historical map overlays from Rumsey collection, current topographic maps can be added as KML add-ons
  3. ^ Full GPS support is increased through having the paid versions (Plus and Pro) [1]
  4. ^ Movie Maker is only available in Pro version [2]
  5. ^ August 6, 2004 - World Wind 1.2 released
  6. ^ Available via built-in MovieRecorder plugin, requires writing a camera script [3]
  7. ^ Microsoft PressPass: Nov. 6, 2006 - Microsoft announced availability of Virtual Earth 3D
  8. ^ Only for United States and Canada
  9. ^ using Google Sky (fully integrated with Google Earth
  10. ^ Google Earth can be extended with many KML add-ons
  11. ^ World Wind supports DirectX 3D polygon mesh models, but buildings can be added only as add-ons, there are no models streamed from servers.
  12. ^ WW includes SDSS imagery (stars, galaxies) which shows about 30% of visible sky.
  13. ^ Users can not only add their own data (images, terrain models, point&vector data), but also add new features through a plugin interface or even modify the program core, if they have experience.
  14. ^ A very large worldwide collection of user created buildings is available via Sketchup Warehouse
  15. ^ World Wind uses Yahoo and Virtual Earth geocoders for street-level address search
  16. ^ Driving directions are found for many other countries, but are limited to major cities and at city-level

[edit] External links

[edit] Other virtual globes

[edit] Misc.