What is a relation OSM?

A relation is a group of elements. In more technical terms, it is one of the core data elements and consists of one or more tags and an ordered list of one or more nodes, ways and/or relations as members which is used to define logical or geographic relationships between other elements.

What are OSM nodes?

A node is one of the core elements in the OpenStreetMap data model. It consists of a single point in space defined by its latitude, longitude and node id. A third, optional dimension (altitude) can also be included: key:ele (abrev. for “elevation”). As of September 2020 , OpenStreetMap contains over 6 billion nodes.

What is OSM size?

osm is the OpenStreetMap data in one file: all the nodes, ways and relations that make up our map. It’s a big file (on 2021-06-01, the plain OSM XML variant takes over 1467.2 GB when uncompressed from the 106.5 GB bzip2-compressed or 59.1 GB PBF-compressed downloaded data file).

What is OSM Standard?

OpenStreetMap (OSM) is a collaborative project to create a free editable geographic database of the world. The data from OSM can be used in various ways including production of paper maps and electronic maps, geocoding of address and place names, and route planning.

Which is an example of a relation in OSM?

Other examples are bus routes (a collections of lines), long and complex objects (rivers or roads), or multiple polygons that are all part of one location (like buildings in a university). There are mainly four types of relations you will encounter in OSM: Multipolygons, Routes, Boundaries, and Restrictions (such as, no left turns).

What can a multipolygon be used for in OSM?

Multipolygons can be used for any complex object that requires inner and outer polygons, like a building or a river with patches of land inside it. Detailed multipolygon information can be found on the OSM Wiki. Relations are also very useful for representing long routes. For example, a bus or bicycle route follows various road segments.

When are nodes and ways are untagged in OSM?

Nodes are often untagged if they are part of ways. Both ways and nodes may be untagged if they are members of a relation. Within the OSM database, we store these attributes for nodes, ways and relations. Your application may not need to make use of all of them, and some third-party extracts produced from OSM data may not reproduce them all.

How is a relation defined in OpenStreetMap wiki?

A turn restriction that says you can’t turn from one way into another way. A multipolygon that describes an area (whose boundary is the ‘outer way’) with holes (the ‘inner ways’). Thus, relations can have different meanings. The relation’s meaning is defined by its tags. Typically, the relation will have a ‘type’ tag.