Displaying data from a GeoJSON file - Polygons

List of federal states (Bundesländer) in Germany

The list of states is shown on the map using representations from a GeoJSON file. The complex definitions of the German states require the use of both types of polygon related elements available under the GeoJSON standard, Polygon and MultiPolygon, along with the use of exterior rings and interior rings.

The use exterior vs interior rings could be seen illustrated for the Brandenburg Bundesland (that surrounds Berlin): since Berlin is a Bundesland of its own, Brandenburg must be drawn containing the cutout of Berlin. This cutout is thus considered an interior ring. Afterwards, Berlin is drawn as a separate polygon that fills that cutout.