Keyhole Markup Language

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Keyhole Markup Language (KML ) is a markup language for describing spatial data for the client components of the programs Google Earth and Google Maps. KML follows the XML syntax is available in version 2.2 before and is a standard of the Open Geospatial Consortium.


Geometry elements

KML documents can include both spatial data in vector as well as raster form. Vector objects such as points, lines, linear rings, polygons or COLLADA models are modeled as Placemark elements and aerial and satellite images as a ground overlay elements.

In addition to the geometry can Placemark elements name, description, predefined style, viewing angle and height, a time stamp, but also any untyped or typed data, such as from a geographical information system include. The same is true for a ground overlay element, a coordinate cut for geo-referencing of raster data must be defined instead of geometry.

Example of a Placemark element within a KML document:

        Zurich < / name>      Zurich < / description>             8.55,47.3666667,0         < / Document > Geodetic Reference System

As a geodetic reference system exclusively the World Geodetic System 1984 is in KML documents used, ie All coordinates are geographic longitude and latitude and, if present, the amount specified above sea level. The height refers to the WGS84 EGM96 geoid.

MIME type

The KMZ is a data- compressed KML file in ZIP format. It can be directly read from the client.

The MIME type for KML files is application / - earth.kml xml or application / - earth.kmz for KMZ files.


In addition to Google Earth, the free KDE Marble program also supports the KML format for viewing directions, but only in OpenStreetMap mode.


The name " Keyhole " is the product Keyhole Earth Viewer the California satellite image Keyhole Corp.. remains that the name of a series of nearly 300 American spy satellites (Keyhole ) back. The company was acquired by Google Inc. in 2004 by the end of October, also based in Mountain View company.

Google KML further developed up to version 2.2, which will be recognized in April 2008 by the Open Geospatial Consortium as a standard and maintained ever since.