3.1 Data services

Provide data via standardised convenience APIs

Paul van Genuchten

2023-05-09

What is OGC?

• Open Geospatial Consortium defines standards for the geospatial industry
• Members are software companies, universities and government
• Such as WMS, GML, OGCAPI, EPSG, GeoSPARQL
• Read more at https://opengeospatial.org

OWS vs OGC API

• The GML and OWS standards are defined on 20**
• Since then the internet moved away from xml
• in 2017 started spatial data on the web experiment with W3C, leading to OGC API
• Currently under development
• Basic support in new and existing products
• The browser as a tool to browse spatial data

OWS vs OGC API

• GML - GeoJSON (json-fg) & HTML
• Long querystrings - Rest api (path parameters)
• GetCapabilities - Open API Specification
• Format=xxx - Content negotiation (accept:text/html)
• Full featured - Minimal standard with extensions

WFS and OGC API - Features

• Provides access to vector features.
• Filter, sorting and pagination options

wms

WMS and OGC API - Maps

• Image rendering of subsets of the data using some styling rules

wms

WMTS, TMS and OGC API - Tiles

• Image or vector representation in tiles on a grid

wms

WCS and OGC API - Coverages

• Grid extracts and calculations

wms

CSW, OGC API - Records and STAC

• Catalogue records
• STAC and OGC API - Records both based on OGC API - Features

Mapserver

• Recent versions of Mapserver support the old and new standards
• Features and Maps
• No tiles (mapproxy), No coverages yet
• No records/stac, by design

Mapfile

• Configuration via a mapfile
• All gdal formats supported
• Create mapfiles using QGIS with geocat bridge

wms

Sensorthings API

• Soil profile data is observation oriented (iso28258)
• Sensorthings API (STA) is an OGC specification for sensor data exchange
• Frost server is an implementation of STA
• Limited availability of clients for STA, Qgis has a STA plugin

Cloud optimised

• Recent interest in cloud optimised and cloud native formats
• Large data files are places in a cloud bucket, users request subsets of the file using range requests
• For grids, Cloud Optimised GeoTiff (COG) and GeoZarr (cloud native)
• For vector, GeoParquet

Sematic web

• To integrate spatial data in the web of knowledge, semantic web standards are relevant
• DCAT for metadata
• GeoSPARQL to define geometries
• SOSA for sensor data
• GLOSIS Web Ontology is a soil ontology based on SOSA and GeoSPARQL