This script generates an accurate GeoJSON for world borders based on OpenStreetMap data. The is a rewrite of simonepri's geo-maps, which generates inaccurate maps for polygons with holes in them (i.e. the South Africa polygon ends up including Lesotho). Additionally, I also included both ISO-3166-alpha-2 and alpha-3 codes (whereas geo-maps only includes alpha-3), and the maps' precision is actually based on distances.
| NPM Package | Resolution | Preview URL* | Package size |
|---|---|---|---|
| @osm_borders/maritime_1m | 1 metre | Preview | 49.9 MB |
| @osm_borders/maritime_2m | 2 metres | Preview | 49.8 MB |
| @osm_borders/maritime_5m | 5 metres | Preview | 49.4 MB |
| @osm_borders/maritime_10m | 10 metres | Preview | 48.2 MB |
| @osm_borders/maritime_20m | 20 metres | Preview | 35.6 MB |
| @osm_borders/maritime_50m | 50 metres | Preview | 21.2 MB |
| @osm_borders/maritime_100m | 100 metres | Preview | 13.7 MB |
| @osm_borders/maritime_200m | 200 metres | Preview | 8.46 MB |
| @osm_borders/maritime_500m | 500 metres | Preview | 4.27 MB |
| @osm_borders/maritime_1000m | 1 kilometre | Preview | 2.47 MB |
| @osm_borders/maritime_2000m | 2 kilometres | Preview | 1.42 MB |
| @osm_borders/maritime_5000m | 5 kilometres | Preview | 706 kB |
| @osm_borders/maritime_10000m | 10 kilometres | Preview | 419 kB |
* Note: For precise packages, the preview may be slow and browser-intensive to load.
Behind the scenes, this script queries the OpenStreetMap Nominatim API. This is actually quite important, since geo-maps' data source, polygons.openstreetmap.fr is the reason as to why polygons with holes were handled improperly.
Maps are simplified using the Douglas-Peucker simplification algorithm provided by mapshaper's simplify-map feature.
Things that could be implemented better: handling changes to OSM IDs (the osm-countries package used by this script is already outdated, and I had to patch it for this code) and including land borders, as well as doing some error handling.
The source code for this project is released under the MIT licence. Map data © OpenStreetMap contributors, released under the ODbL licence.