Keyhole Markup Language

Keyhole Markup Language is an XML-based language used for expressing geographic annotation and visualization within Internet-based, two-dimensional maps and three-dimensional Earth browsers like Google Earth, Google Maps, and NASA WorldWind. It was developed by Keyhole, Inc., which was acquired by Google in 2004, and has since become an Open Geospatial Consortium standard, supported by Esri, Autodesk, and the United States Geological Survey. The language is also used by other geographic information system (GIS) applications, including ArcGIS and QGIS, to create and share geospatial data.

Introduction

The Keyhole Markup Language is used to describe and visualize geospatial data, including placemarks, paths, and polygons, in an XML-based format. This allows users to create custom maps and share them with others, using applications like Google My Maps and Google Earth. The language is also used by GIS professionals, such as those at the National Geospatial-Intelligence Agency and the United States Census Bureau, to create and analyze geospatial data. Additionally, the language is supported by GPS devices, such as those from Garmin and TomTom, and by web mapping applications, including Leaflet and OpenLayers.

History

The Keyhole Markup Language was developed by Keyhole, Inc., a company founded by John Hanke in 2001, and was first released in 2004. The language was initially used by Keyhole, Inc.'s EarthViewer application, which was later acquired by Google and renamed Google Earth. The language became an Open Geospatial Consortium standard in 2008, with the support of Esri, Autodesk, and the United States Geological Survey. Today, the language is widely used by GIS professionals and developers, including those at the National Park Service and the Federal Emergency Management Agency.

File Structure

A Keyhole Markup Language file typically consists of a series of XML elements, including placemarks, paths, and polygons. These elements are used to describe and visualize geospatial data, such as points, lines, and areas. The language also supports the use of styles and schemas, which allow users to customize the appearance and structure of their maps. For example, the United States Geological Survey uses the language to create and share maps of national parks, while the National Oceanic and Atmospheric Administration uses it to create maps of ocean currents and weather patterns.

Applications

The Keyhole Markup Language is used by a wide range of applications, including Google Earth, Google Maps, and NASA WorldWind. It is also supported by GIS applications, such as ArcGIS and QGIS, and by web mapping applications, including Leaflet and OpenLayers. The language is used by GIS professionals, such as those at the National Geospatial-Intelligence Agency and the United States Census Bureau, to create and analyze geospatial data. Additionally, the language is used by GPS devices, such as those from Garmin and TomTom, and by mobile apps, such as Google Maps and Waze.

Features

The Keyhole Markup Language supports a wide range of features, including placemarks, paths, and polygons. It also supports the use of styles and schemas, which allow users to customize the appearance and structure of their maps. The language is also extensible, allowing developers to create custom elements and attributes. For example, the United States Geological Survey uses the language to create and share maps of earthquakes and volcanic eruptions, while the National Weather Service uses it to create maps of weather forecasts and warnings.

Comparison to Other Formats

The Keyhole Markup Language is similar to other geospatial data formats, such as GeoJSON and GML. However, it has several advantages, including its support for three-dimensional visualization and its ability to be used with a wide range of applications. The language is also widely supported by GIS professionals and developers, including those at the National Park Service and the Federal Emergency Management Agency. Additionally, the language is used by research institutions, such as the Massachusetts Institute of Technology and the University of California, Berkeley, to create and share geospatial data. Category:Geospatial data formats