County Townland Geometry Datasets
Townland datasets are provided by county and with multiple levels of precision and accuracy available (see below). Start off by navigating to a county page from the adjacent list. On each page, you will be able to see and download the files that are available for that county.
Using the datasets
To use the geoJSON files provided in WME, they can be loaded onto the map using the WME Geometries script provided by Timbones.
See Using the townland datasets in WME to find out more.
More about the datasets
Dataset precision Generalised vs. Ungeneralised
For each level of accuracy for each dataset, there are three precision sets available. Generalised (20m), Generalised (50m) and Ungeneralised.
Ungeneralised datasets are the most precise available. The coordinates of the nodes in the geometry files are as precise as they were originally measured. This usually means that you will see smooth townland boundaries.
Generalised (20m) datasets are a middle level of precision. The coordinates of the nodes in the geometry files are within 20m of their actual positions. This usually means that you will see somewhat rough townland boundaries.
Generalised (50m) datasets are the least precise that we provide. The coordinates of the nodes in the geometry files are within 50m of their actual positions. This usually means that you will see rough townland boundaries.
Dataset accuracy Full vs. Reduced
For each level of precision for each dataset, there are two accuracy sets. Full and reduced.
Full datasets are the highest precision available. They achieve high precision by storing more decimal places of the coordinates for nodes in the geometry files. As a result, these files are larger, and place more load on the map editor. For townlands, unless they are particularly dense in a region, reduced datasets are acceptable to use.
Reduced datasets have improved file size and performance in the editor at the expense of some of the data's accuracy. They achieve this by storing fewer deciaml places of the coordinates for nodes in the geometry files. These files are usually acceptable to use when it comes to adding townland boundary information to the map.