Dasymetric Mapping

Dasymetric mapping is a geospatial technique that uses information such as landcover types to more accurately distribute data that have been assigned to arbitrary boundaries like census blocks.

The image on the left shows a map of the population by block group based solely on the census data. The image on the right shows the dasymetric population allocation for several block groups in Tampa, Fla.

• EnviroAtlas uses dasymetric mapping to spatially distribute census data, which assumes the population is even across each block, based on land cover classifications in the National Land Cover Database (NLCD).
• By removing areas that are uninhabitable, such as open water and slopes greater than 25 percent, researchers can better estimate where people live.
• EnviroAtlas researchers use the dasymetric data to calculate the distribution of ecosystem services, and other metrics including walking distances, viewsheds, resource use, and exposure potential.
• For more information on the Dasymetric data created for EnviroAtlas, read the Dasymetric Allocation of Population Fact Sheet.

Intelligent Dasymetric Mapping (IDM) Toolbox

The Intelligent Dasymetric Mapping (IDM) Toolbox is available to download based on the version of ArcGIS software implemented.

The latest release of the IDM Toolbox uses ArcPy and arcpy.da functionality and improves the tool's performance. This version requires ArcGIS 10.3 or higher. The ArcPy toolbox contains a number of scripts that assist preparing vector population and raster ancillary datasets for intelligent dasymetric mapping, performs the dasymetric calculations, and then generates a floating point output raster of revised population density. Please see the documentation in the zip file for more information on the individual tools.

• Download the IDM Toolbox for ArcGIS 10.3 (ZIP)  (75 K, August 2015)

The ArcGIS 10.2 version below contains bug fixes related to broken links within the included models and minor code changes that should speed processing from previous versions. Please note this toolbox is available for ArcGIS 10.2 (may work for 10.0 and  10.1, but not tested) and ArcPy, 4/16/15.

• Download the IDM Toolbox for ArcGIS 10.2 (ZIP)(65 K, April 2015)