This MedLibrary.org supplementary page on Keyhole Markup Language is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
| Filename extension | .kml, .kmz |
|---|---|
| Internet media type | application/vnd.google-earth.kml+xml, application/vnd.google-earth.kmz |
| Developed by | Keyhole, Inc., Google |
| Type of format | Geographic Information System |
| Extended from | XML |
Keyhole Markup Language (KML) is an 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. The name "Keyhole" is a homage to the KH reconnaissance satellites, the original eye-in-the-sky military reconnaissance system first launched in 1976.
Contents |
Structure
The KML file specifies a set of features (placemarks, images, polygons, 3D models, textual descriptions, etc.) for display in Google Earth, Maps and Mobile, or any other 3D earth browser (geobrowser) implementing the KML encoding. Each place always has a longitude and a latitude. Other data can make the view more specific, such as tilt, heading, altitude, which together define a "camera view". KML shares some of the same structural grammar as GML[1]. Some KML information cannot be viewed in Google Maps or Mobile [2].
KML files are very often distributed as KMZ files, which are zipped KML files with a .kmz extension. When a KMZ file is unzipped, a single "doc.kml" is found along with any overlay and icon images referenced in the KML.
Example KML document:
<?xml version="1.0" encoding="UTF-8"?> <kml xmlns="http://www.opengis.net/kml/2.2"> <Placemark> <name>New York City</name> <description>New York City</description> <Point> <coordinates>-74.006393,40.714172,0</coordinates> </Point> </Placemark> </kml>
The MIME type associated with KML is application/vnd.google-earth.kml+xml; the MIME type associated with KMZ is application/vnd.google-earth.kmz.
Geodetic reference systems in KML
For its reference system, KML uses 3D geographic coordinates: longitude, latitude and altitude, in that order. The longitude, latitude components are as defined by the World Geodetic System of 1984 (WGS84). The vertical component (altitude) is measured from the 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) is assumed. A formal definition of the coordinate reference system (encoded as GML) used by KML is contained in the OGC KML 2.2 Specification. This definition references well known EPSG CRS components.
OGC standard process
The KML 2.2 specification was submitted to the Open Geospatial Consortium to assure its status as an open standard for all geobrowsers. In November 2007 a new KML 2.2 Standards Working Group was established within OGC to formalize KML 2.2 as an OGC standard. Comments were sought on the proposed standard until January 4, 2008,[1] and it became an official OGC standard on April 14, 2008.[2]
Applications using KML
- ArcGIS Explorer
- Feature Manipulation Engine (FME)
- Flickr
- EarthSpector GIS
- Google Earth
- Google Maps
- Google Mobile
- Live Search Maps
- Microsoft Virtual Earth
- Map My Ancestors
- Mapufacture
- Marble (KDE)
- OpenLayers
- Ossimplanet
- Platial
- QStarz Travel Recorder
- RouteBuddy for Mac
- WikiMapia
- World Wind
- Yahoo Pipes
- SuperMap iServer (SuperMap IS) .NET and Java
- OpenLAPI, an LGPL implementation of the Location API for Java ME
See also
- Geospatial Content Management System
- CityGML
- Geography Markup Language
- GPX (data transfer)
- Point of Interest
- Waypoint
- COLLADA
References
- ^ Open Geospatial Consortium, Inc (2007-12-04). "The OGC Seeks Comment on OGC Candidate KML 2.2 Standard". Press release. Retrieved on 2007-12-10.
- ^ Shankland, Stephen (2008-04-14). "Google mapping spec now an industry standard". CNET. Retrieved on 2008-04-14.
 |
This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (January 2008) |
External links
- OGC KML 2.2 Standard
- OGC Official KML 2.2 Schema
- Google KML Documentation
- KML Validator
- Developer Knowledge Base: KML in Google Earth
- KML Developer Support group
- KMLImporter importing placemarks into NASA World Wind
- Use hierarchical maps (Mindmaps) to create and manage KML files and convert Excel data to KML.
- Google Earth Connectivity Add-on for ArchiCAD 9
- Validate your KML (Online or Offline!), Google Maps API Blog.
- Paste KML directly onto a Google Map
- kmlwiki.net - Include KML files directly into a 2D or 3D Wikimap
Wikipedia content modification information:
- This page was last modified on 8 October 2008, at 13:32.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Keyhole Markup Language".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.