Compare methods

	Cartogram Construction	Dasymetric Mapping
Field	Human Geography	Human Geography
Family	Process / pipeline	Process / pipeline
Year of origin	2004	2003
Originator	Cartogram tradition (diffusion method by Gastner & Newman; circular method by Dorling)	J. K. Wright (introduced 1936); modern surface method by Jeremy Mennis
Type	Map transformation that rescales region area to represent a variable	Cartographic areal-interpolation technique using ancillary data
Seminal source	Gastner, M. T., & Newman, M. E. J. (2004). Diffusion-based method for producing density-equalizing maps. Proceedings of the National Academy of Sciences, 101(20), 7499–7504.	Mennis, J. (2003). Generating surface models of population using dasymetric mapping. The Professional Geographer, 55(1), 31–42.
Aliases	Value-by-Area Map, Area Cartogram, Density-Equalizing Map, Anamorphic Map	Dasymetric Map, Dasymetric Interpolation, Ancillary-Based Areal Interpolation, Population Surface Mapping
Related	4	4
Summary	A cartogram is a map in which the area of each region is rescaled so that it is proportional to some variable — population, votes, GDP — rather than to its true geographic size. The aim is to correct the visual bias of ordinary maps, where large but sparsely populated regions dominate the eye while small, populous ones nearly vanish, by making each region as big as the quantity it represents. Cartogram construction is the family of techniques that produce these value-by-area maps, ranging from contiguous density-equalizing diffusion to non-contiguous circle and rectangle methods, each balancing the accuracy of areas against the recognizability of shapes.	Dasymetric mapping is a cartographic and areal-interpolation technique that redistributes data reported for arbitrary administrative zones — such as census counts — onto more meaningful boundaries derived from ancillary information about where the phenomenon actually occurs. Instead of pretending population is spread evenly across a census tract, it uses land cover or land use to push people into the residential parts and out of lakes, parks, and industry, producing a far more realistic population surface while preserving each zone's reported total.