APIs

APIs#

What is an API?#

API stands for Application Programming Interface. It is an interface using which you or another computer can communicate with a computer by sending requests.

APIs for downloading OpenStreetMap (OSM)#

There are many ways to download OSM data. e.g.

The ohsome API#

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Fig. 3 Sending a request to the ohsome API and retrieving data#

What can you do with it?#

Download OSM data

../../../_images/trees.jpg

Fig. 4 Extract trees mapped in Heidelberg Bahnstadt#

Download the history of OSM features

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Fig. 5 Temporal evolution of buildings with (green) and without address (red) in OSM within Heidelberg.#

Learn how to create this animation here

Count the number of active OSM users

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Fig. 6 Number of active OSM users#

How to send a request to the ohsome API#

See documentation for full list of endpoints on Data Extraction and Data Aggregation.

Example: Query all trees in Heidelberg’s Bahnstadt on 1. Nov 2022#

Endpoint: https://api.ohsome.org/v1/elements/geometry

Parameters

Send as POST Request (recommended)

Requires a program to send requests e.g., cUrl in the command line

curl -X POST \
--data-urlencode "bboxes=8.65443,49.39444,8.68533,49.40824" \
--data-urlencode "time=2022-11-01" \
--data-urlencode "filter=natural=tree" \
-o trees_2022.geojson \
"https://api.ohsome.org/v1/elements/geometry"

Result

../../../_images/trees.jpg

Fig. 7 Trees in Heidelberg Bahnstadt mapped in OSM up until 1. Nov 2021#

Alternative: Send as GET Request via the browser

The same query can be sent as a GET request:

Query URL: {Endpoint}?{parameter}&{parameter}…

Example: Click on the link below to send the request via the broswer

https://api.ohsome.org/v1/elements/geometry?bboxes=8.65443,49.39444,8.68533,49.40824&filter=natural=tree&time=2022-11-01

There are other APIs such as the emissions API which only offer GET requests. (see API documentation)

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