What Is OpenStreetMap? Open Data for QGIS

Introduction

OpenStreetMap (OSM) is a project that provides open data on all kinds of features, from vending machines and trash cans on the street to campgrounds.

This article explains the features of OpenStreetMap and how to use it in QGIS.

What is OpenStreetMap?

OpenStreetMap is a project that creates map data anyone can use freely. It was founded in the United Kingdom in 2004 and is now a worldwide project.

Features of OpenStreetMap

OpenStreetMap has three main features: it is open data, anyone can take part in editing it, and it is widely used.

Open data

First, OpenStreetMap is open data.

Other map services may charge for data use or restrict how you use it. OpenStreetMap, on the other hand, is provided under the Open Database License (ODbL), and anyone can use it freely at no cost as long as they provide attribution.

For detailed terms of use, see Copyright and License on the OpenStreetMap website.

Anyone can take part in editing

Second, anyone can take part in editing.

In OpenStreetMap, anyone with an account can edit, as on Wikipedia. Users can add shops and roads based on location data from a smartphone's GPS, and add roads and buildings by referring to aerial imagery that is permitted for use.

Inaccurate information can also be corrected later, which improves quality. Companies and organizations, not just individuals, also take part in editing and work on quality improvement. Large companies such as Meta and Microsoft use AI and other techniques to improve quality.

If you are interested in editing, see the OpenStreetMap Wiki: Getting Involved page.

Used in a wide range of places

Third, OpenStreetMap is used in a wide range of places, from public services to games.

The Humanitarian OpenStreetMap Team is a project in which users around the world work together to edit map data for regions that need humanitarian aid. For example, when a natural disaster occurs, participants add and edit roads and buildings in OpenStreetMap using aerial photographs as a reference. The project has been activated for events such as the Noto Peninsula Earthquake, the Kumamoto Earthquake, and the Great East Japan Earthquake. The added data helps on the ground with assessing damage and with rescue operations.

Wheelmap is another project that uses OpenStreetMap. It is a website where wheelchair users can check whether facilities and roads are wheelchair accessible and report their accessibility status.

As these examples show, OpenStreetMap is often used as a foundation for public-interest services such as rescue operations and accessibility, but it is also used for entertainment. For example, some location-based games, starting with Pokémon Go, use it.

Data model

OpenStreetMap represents everything on the map with three elements: nodes, ways, and relations. A node represents a point. A way represents a line, such as a road, a boundary, or the outline of a building. A relation represents a complex feature made by combining multiple nodes and ways.

By adding tags to nodes, ways, and relations, you can express attributes such as “this is a post box,” “this is a national highway,” and “this is a building.”

In the node example (a post box), in addition to the tag that marks it as a post box, tags such as the operator (operator, operator:en) are attached.

In the way example (part of a national highway), in addition to the tag that marks it as a national highway, tags such as the name (name, name:ja), the number of lanes (lanes), and the road surface (surface) are attached.

In the relation example (a pedestrian walkway), multiple ways form a multipolygon.

A tag consists of a “key” and a “value” and takes one of two main forms. In the first, the key gives a broad category and the value gives a detailed one. For example, amenity=post_box is a post box, and highway=trunk is a national highway. In the second, the key gives an attribute and the value gives its specific value. For example, opening_hours=09:00-21:00 means “the opening hours are 9 a.m. to 9 p.m.,” and name=セイコーマート means “the name is Seicomart.”

To check the main tags, see the Map features and How to map a pages of the OpenStreetMap Wiki.

A key and its value are conventionally written as key=value.

Features of OpenStreetMap data

Advantages

Compared with other open data, OpenStreetMap stands out for its real-time updates and variety of data. Map data from organizations such as the Geospatial Information Authority of Japan (GSI) is generally updated on a yearly basis, but changes in OpenStreetMap appear on the website within minutes. Other open data also mostly covers public facilities such as schools and stations, whereas OpenStreetMap includes a wide range of data: public institutions, of course, but also vending machines and trash cans on the street and campgrounds.

Disadvantages

Compared with other data, OpenStreetMap has the problem of lower completeness and accuracy.

This is because the data relies on edits by users. In areas where editing is not active, information on roads and facilities may be missing or out of date.

Users can also write and create tags freely. The user community defines how to use the basic tags, and these are documented on the OpenStreetMap Wiki, but some tags are rarely used, and typos may exist.

However, data with low completeness or accuracy is also an opportunity for improvement. When you find such a spot, try adding or updating the information yourself and contribute to the project.

Using OpenStreetMap data in QGIS

To use OpenStreetMap data for analysis or map making in QGIS, you first need to get the data. You can use the following services and QGIS plugins to get it.

Geofabrik

Geofabrik is a site that provides OpenStreetMap data cut out by country and region. OpenStreetMap officially provides data only for the entire planet, but with Geofabrik you can get data by region, country, or area, such as all of Asia, all of Japan, or all of Hokkaido.

The data is distributed in formats that QGIS can handle (.shp, .pbf).

QuickOSM

QuickOSM is a QGIS plugin that lets you get data from OpenStreetMap inside QGIS. Everything, including narrowing down to only the data that meets your conditions, happens in QGIS.

The plugin is built on the Overpass API, which can extract features from OpenStreetMap data based on conditions.

overpass turbo

overpass turbo is a web-based tool for running Overpass API queries. With it, you can search the OpenStreetMap database with specific conditions and see the results on a map right away. You can also view the attribute data of the results, not just see them on the map.

You can download the results in formats such as GeoJSON, so you can display them in QGIS right away.

Using OpenStreetMap as a basemap

QGIS includes the settings for using OpenStreetMap as a basemap by default, so it is easy to use.

The following article explains the steps for using OpenStreetMap as a basemap in detail.

Conclusion

This article introduced the features of OpenStreetMap, its basic concepts, and how to use it in QGIS. OpenStreetMap is map data that anyone can use freely, and its wealth of information makes it valuable data for QGIS users when they make maps or run analyses. Give it a try.

OpenStreetMap is also supported by the contributions of many people. Besides using the map, you can join the project by adding and correcting data in your own neighborhood.

Why not enjoy making maps, not just using them?

References

• https://www.jstage.jst.go.jp/article/jkg/69/6/69_238/_article/-char/ja/
• https://blog.openstreetmap.org/2024/12/19/meta-contributes-to-178k-eur-to-openstreetmap/
• https://learnosm.org/ja/coordination/HOT-Remote-Response-Guide/
• https://www.yhmf.jp/as/postnumber/vol_69_04.html
• https://wiki.openstreetmap.org/wiki/Elements