- geocoding, i.e. finding the X and Y coordinates of a location determined by an address.
- reverse geocoding, i.e. finding the address based on the given X and Y coordinates.
The quality of geocoding, i.e. the percentage of points located correctly from the entire list of addresses, depends on several factors:
- The quality of the geocoding engine (e.g. the string comparison methodology used)
- The quality of the reference data, i.e. the address points on which the geocoding is based
- The quality of the geocoding data (e.g. the number of typos in the addresses)
Very rarely do geocoders occur as separate software in companies or institutions (mainly due to the need to continuously update the reference address database) Most often geocoders occur as services e.g.
- Address Finder in Google Maps app. This is a geocoder capable of searching for addresses worldwide.
- Universal Geocoding Service – API for Poland provided by GUGiK
Popular desktop GIS applications (e.g. QGIS or ArcGIS) are not geocoders either. QGIS has several plug-ins e.g. Location Lab, which are connectors between QGIS and the services mentioned above.
Frequently asked questions
Can I geocode through table joins in QGIS?
You can, but the result will be very imperfect. There is almost never a perfect situation in which both the reference address point and the address to be geocoded will be saved perfectly in the same form. Any deviation, e.g. a typo, or the inclusion of a premises number will cause the join to fail.