Geographic Information System (GIS) - KML
KML – Keyhole Markup Language: XML-based language schema for expressing geographic annotation and visualization on existing (or future) Web-based, two-dimensional maps and three-dimensional Earth browsers
KML was developed for use with Google Earth, which was originally named Keyhole Earth Viewer. It was created by Keyhole, Inc, which was acquired by Google in 2004. KML became an international standard of the Open Geospatial Consortium in 2008. Google Earth was the first program able to view and graphically edit KML files. Other projects such as Marble have also started to develop KML support.
For its reference system, KML uses 3D geographic coordinates: longitude, latitude and altitude, in that order, with negative values for west, south and below mean sea level if the altitude data is available. The longitude, latitude components (decimal degrees) are as defined by the [[World Geodetic System|World Geodetic System of 1984 (WGS84)]]. The vertical component (altitude) is measured in meters from the [[EGM96|WGS84 EGM96 Geoid vertical datum]]. If altitude is omitted from a coordinate string, e.g. (−122.917, 49.2623) then the default value of 0 (approximately sea level) is assumed for the altitude component, i.e. (−122.917, 49.2623, 0).
KML – Keyhole Markup Language: XML-based language schema for expressing geographic annotation and visualization on existing (or future) Web-based, two-dimensional maps and three-dimensional Earth browsers