KML

KML is an XML-based markup language designed to represent geographic annotations and visualizations for two-dimensional maps and three-dimensional Earth browsers. Initially developed by Keyhole, Inc. and later popularized by Google in consumer products, it enables users to encode placemarks, overlays, paths, and model placements for applications such as Google Earth, Google Maps, and various geographic information systems. KML functions as an exchange format within a broader ecosystem involving organizations like the Open Geospatial Consortium and software from companies including Esri and Mapbox.

Overview

KML provides a schema for describing geographic features with tags that encode coordinates, styling, and behavior for rendering in viewers such as Google Earth, NASA World Wind, and third-party viewers used by institutions like the United States Geological Survey and National Aeronautics and Space Administration. It sits alongside formats such as GeoJSON, GML (Geography Markup Language), and Shapefile as part of spatial data interchange among agencies including the European Space Agency and commercial vendors like Maxar Technologies. Widely adopted in projects ranging from humanitarian mapping by OpenStreetMap contributors to scientific visualization by NOAA, KML facilitates sharing of placemarks, tours, and time-enabled features.

History and Development

KML originated at Keyhole, Inc., a company whose software underpinned the CIA-backed company’s mapping client used by early adopters and later acquired by Google in 2004. After acquisition, Google integrated KML into Google Earth and released parts of the specification to the public. In 2008 the Open Geospatial Consortium formalized KML as an OGC standard, harmonizing it with other standards such as KVP-based schemas and aligning with practices used by agencies like USGS and NOAA. Subsequent iterations addressed 3D models via COLLADA, time primitives inspired by ISO 8601, and extensions used by academic projects at institutions like Stanford University and MIT.

File Format and Syntax

KML files are XML documents typically using the .kml file extension, optionally packaged in a .kmz archive which is a zipped bundle compatible with viewers such as Google Earth Pro and ArcGIS Pro. The root element contains a or with child elements including ,