OpenHistoricalMap based on OpenStreetMap
Nodes are points with a geographic position, stored as coordinates (pairs of a latitude and a longitude) according to WGS 84. Outside of their usage in ways, they are used to represent map features without a size, such as points of interest or mountain peaks.
Ways are ordered lists of nodes, representing a polyline, or possibly a polygon if they form a closed loop. They are used both for representing linear features such as streets and rivers, and areas, like forests, parks, parking areas and lakes.
Relations are ordered lists of nodes, ways and relations (together called "members"), where each member can optionally have a "role" (a string). Relations are used for representing the relationship of existing nodes and ways. Examples include turn restrictions on roads, routes that span several existing ways (for instance, a long-distance motorway), and areas with holes.
Tags are key-value pairs (both arbitrary strings). They are used to store metadata about the map objects (such as their type, their name and their physical properties). Tags are not freestanding, but are always attached to an object: to a node, a way or a relation. A recommended ontology of map features (the meaning of tags) is maintained on a wiki. New tagging schemes can always be proposed by a popular vote of a written proposal in OpenStreetMap wiki, however, there is no requirement to follow this process. There are over 89 million different kinds of tags in use as of June 2017.The OpenStreetMap data primitives are stored and processed in different formats.
The main copy of the OpenStreetMap data is stored in OpenStreetMap's main database. The main database is a PostgreSQL database, which has one table for each data primitive, with individual objects stored as rows. All edits happen in this database, and all other formats are created from it. Data from Nominatim(OSM) and if required GeoNames is used for the search in OpenStreetMap.For data transfer, several database dumps are created, which are available for download. The complete dump is called planet.osm. These dumps exist in two formats, one using XML and one using the Protocol Buffer Binary Format (PBF).Sister projects
Several open collaborative mapping projects integrate with the OpenStreetMap database or are otherwise affiliated with the OpenStreetMap project:OpenHistoricalMap is a world historical map based on the OpenStreetMap software platform.
OpenRailwayMap is a detailed online map of the world's railway infrastructure, built on OpenStreetMap data. It has been available since mid-2013 at openrailwaymap.org.
OpenSeaMap is a world nautical chart built as a mashup of OpenStreetMap, crowdsourced water depth tracks, and third-party weather and bathymetric data.
Wheelmap.org is a portal for mapping, browsing, and reviewing wheelchair-accessible places.