Map of the distribution of the velar nasal initial (ŋ) in local Chinese dialects in the core Chinese-speaking area, reflecting fieldwork conducted between December 2002 and December 2006.
Own work

Dialect data from Cao Zhiyun (ed.) (2008) Linguistic Atlas of Chinese Dialects (汉语方言地图集), vol. 1 Phonetics, Map 043.
Voronoi polygons generated using QGIS
Coastline and lakes from Natural Earth 1:10m Physical Vectors
Boundaries from Natural Earth 1:10m Cultural Vectors
Conversion to SVG using svgis
Kanguole