Virtual globe

Virtual globe:A virtual globe is a 3D software model or representation of the Earth 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 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.
In 1998, Microsoft released a popular offline virtual globe in the form of Encarta Virtual Globe 98. The first widely publicized online virtual globe was Google Earth.

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.
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:

• NASA World Wind, USGS topographic maps and several satellite and aerial image datasets, the first popular virtual globe along with Google Earth. World Wind is open source software.
• Google Earth, satellite & aerial photos dataset (including commercial DigitalGlobe images) with international road dataset, the first popular virtual globe along with NASA World Wind.
• Microsoft Virtual Earth, 3D interface for Live Search Maps, runs inside Internet Explorer and Firefox, and uses Nasa Blue Marble Next Generation.
• Marble, part of the K Desktop Environment, with data provided by OpenStreetMap, as well as Nasa Blue Marble Next Generation and others. Marble is open source software.
• ArcGIS Explorer a lightweight client for ArcGIS Server, supports WMS and many other GIS file formats.
• EarthBrowser, A Flash / Adobe AIR based virtual globe with real-time weather forecasts, earthquakes, volcanoes, and webcams.
• Software MacKiev's 3D Weather Globe & Atlas, 3D views based on the Blue Marble imagery, near-real-time cloud coverage and weather forecast from CustomWeather, time zones, day/night views.
• Earth3D, a program that visualizes the earth in a realtime 3D view. It uses data from NASA, USGS, the CIA and the city of Osnabrück. Earth3D is open source software.

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.[...]