The KML file type, which stands for Keyhole Markup Language, is a widely used format for expressing geographic annotation and visualization within two-dimensional maps and three-dimensional Earth browsers. Initially developed for use with Google Earth, which was known as Keyhole Earth Viewer before Google's acquisition, KML has evolved through the years to become an international standard maintained by the Open Geospatial Consortium (OGC).
How KML Functions
KML files are XML-based and serve to manage the display of geospatial data, including points, lines, images, polygons, and models, on a map. The structure of a KML document allows for the nesting of elements within each other, organizing and grouping data effectively. The functionality also includes the ability to control the appearance of elements on a map, assign names, descriptions, and attach images and links.
Software Integration
Aside from Google Earth, numerous software applications support the KML format. GIS (Geographic Information Systems) software like ArcGIS and QGIS, as well as various web mapping services, all allow for the integration, creation, and editing of KML files. KML functionality is also present in many mobile applications to enable the overlay of data on map interfaces.
Alternatives to KML
While KML is robust and widely accepted, alternative formats such as GeoJSON and CityGML exist. GeoJSON is a format using JSON (JavaScript Object Notation) specifically for encoding a variety of geographic data structures. CityGML is an open standardized format that allows for the storage and exchange of virtual 3D city and landscape models.
Understanding the history, functionality, and software compatibility is crucial for those working with geographic data and map-based applications. With the ongoing development of geospatial technologies, the pertinence of formats like KML remains significant, not only for professionals in the field of GIS but also for enthusiasts and developers of location-based services.