Welcome to the Homepage of Cartogram Computation Group
Cartograms are used for visualizing geographically distributed data by scaling the regions
of a map (e.g., countries in Europe) such that their areas are proportional to the data
associated with them (e.g., GDP). Thus the cartogram computation problem can be thought
of as a map deformation problem where the input is a planar polygonal map and an assignment
of some positive weight for each region. The goal is to create a deformed map where the
area of each region realizes the weight assigned to it (no cartographic error) while the
overall map remains recognizable (e.g., the topology, the relative positions and the shapes
of the regions remain the same). Since achieving no cartographic error and preserving map
readability are impossible to achieve simultaneously, all the cartogram generation algorithms
tolerate some error in one or both of these criteria.
We define some quantitative measures that can be used to evaluate how faithfully a cartogram
represents the weights, as well as several measures for evaluating the readability of the
final representation. We then study several early algorithms for computing cartograms and
two new ones and compare them in terms of our quantitative measures.