Points of interest
A point of interest or POI is a feature on a map (or in a geodataset) that occupies a particular point, as opposed to linear features like roads or areas of landuse. A point of interest is not necessarily very interesting, so, for example, post boxes are relatively interesting/uninteresting, depending on context and your subjective opinion. The term POI is actually quite imprecise, but is widely recognised by users of satellite navigation systems (SATNAVs), who are often presented with options to show or hide points of interest. It's also for geocaching and GIS users, but "POI" takes on different meanings in different GIS systems.
Some example of types of POI:
- Churches, schools, town halls, distinctive buildings
- Post offices, shops, postboxes, telephone boxes
- Pubs (pub names are useful when navigating by map)
- Car parks and lay-bys (and whether free or not)
- Speed cameras
- Tourist attractions
POIs in OpenStreetMap
Nodes are certainly used to represent POIs, but the concepts don't map directly across. For example nodes are also used as part of ways to represent linear features. You might regard all standalone nodes (nodes that are not part of a way) as representing points of interest; however, a point of interest can actually be part of the way, for instance, a railway level crossing.
POIs are drawn as areas in some cases (and increasingly more frequently with the availability of more high resolution imagery). Data users might try to simplify areas down to a centroid point. Provided mappers have followed the One feature, one OSM element mapping practice, this should work reasonably well.
POIs from OpenStreetMap on my device
Some devices (satnavs, GPS units, smartphone apps) will support display of POIs provided you can load them in the required format. Particularly in the case of SATNAVs, map data is often represented using encryption, which allows the manufacturer control to prevent you loading any data (free OpenStreetMap data) onto your device. And you thought you owned it! Interestingly though some such devices will allow POI data to be overlayed in a more open fashion.
To find out how to load POI data from OpenStreetMap onto your device (or whether its possible to do so) you can hopefully find some helpful information on the wiki. Look for your brand of device, e.g., linked from the GPS Reviews page. In the absence of any information (Please help add this to the wiki!) you should investigate features for displaying POIs, or "waypoints". There may be files on the storage media, or procedures for transferring data onto the device by USB cable.
In some cases POI files are available as prepared downloads.
- One feature, one OSM element
- Contribute map data
- Openlayers POI layer example — Explains how to show POI markers on an OSM slippy map by using an overlay layer
- W3C Working Draft specification for a POIs standard (There is no known OSM software related to this yet.)
- Tool for extracting POIs from OSM binary files
- HTTP API to query POIs extracted from OSM planet file
- SearchOSM Search OSM for POIs by name and/or category and/or area.
- Waypointer Search POI on map by category, download POI in different formats.
- OsmPoisPbf is a Java based tool for scanning an OpenStreetMap file for nodes and areas (and relations) whose tags indicate them as POIs (points of interest) and extracts those into a comma separated file (CSV).