Dasymetric Mapping

A dasymetric map is a type of thematic map intended to represent a statistical surface of density, most commonly population density. The process of dasymetric mapping refers to the transformation of data encoded in a choropleth map into a dasymetric map, or at least a representation that better approaches a dasymetric map. The process incorporates an ancillary data layer, typically an area‐class map. The source zones of the choropleth map are then overlaid with the ancillary data to produce a new set of target zones for which population density is estimated. Parameterizing the functional relationship between the ancillary data classes and the underlying population density surface is typically done by collecting a sample of ancillary data observations for which population density can be established. Statistical approaches, such as regression, can then be employed to estimate population density for the target zones of the dasymetric map.