topic.md

Topic

A topic describes the request which should be made to the ohsome API. Each topic is representative of a specific set of features, aggregated information or user statistics derived from the OpenStreetMap database. Each topic is defined by the ohsome API endpoint, an aggregation_type and the filter parameter. In addition, each topic preset has a key, name, description, a list of valid indicators and a list of projects the topic belongs to. Topic presets are written down as YAML file at ohsome_quality_api/topics/presets.yaml

Example

building-count:
  name: Building Count
  description: >-
    All buildings as defined by all objects tagged with 'building=*'.
  endpoint: elements
  aggregation_type: count
  filter: building=* and geometry:polygon
  indicators:
    - mapping-saturation
    - currentness
    - attribute-completeness
  projects:
    - core

How to Add a New Topic?

First create an ohsome API query to retrieve desired information from the ohsome API. Helpful resources for this task are:

• The Swagger UI of the ohsome API: https://api.ohsome.org/v1/swagger-ui.html
• ohsome API documentation on the aggregation_type and endpoint parameters: https://docs.ohsome.org/ohsome-api/stable/endpoints.html
• ohsome API documentation on the filter parameter: https://docs.ohsome.org/ohsome-api/stable/filter.html

Second translate the query parameters into a topic preset and extent this file: ohsome_quality_api/topics/presets.yaml.