TopoJSON

[1] topojson-specification/README.md at master · topojson/topojson-specification (2015-05-21 10:33:13 +09:00 版) <https://github.com/topojson/topojson-specification/blob/master/README.md>

[2] Mapping geoJSON files on GitHub - User Documentation (2015-05-20 18:36:45 +09:00 版) <https://help.github.com/articles/mapping-geojson-files-on-github/>

[3] topojson/topojson: An extension of GeoJSON that encodes topology! 🌐 (2018-03-13 20:26:05 +09:00) <https://github.com/topojson/topojson>

TopoJSON is an extension of GeoJSON that encodes topology. Rather than representing geometries discretely, geometries in TopoJSON files are stitched together from shared line segments called arcs. This technique is similar to Matt Bloch’s MapShaper and the Arc/Info Export format, .e00.