Editing Cartogram (section)

== General principles ==
Since the early days of the academic study of cartograms, they have been compared to [[map projection]]s in many ways, in that both methods transform (and thus distort) space itself.<ref name="tobler1963" /> The goal of designing a cartogram or a map projection is therefore to represent one or more aspects of geographic phenomena as accurately as possible, while minimizing the collateral damage of distortion in other aspects. In the case of cartograms, by scaling features to have a size proportional to a variable other than their actual size, the danger is that the features will be distorted to the degree that they are no longer recognizable to map readers, making them less useful.

As with map projections, the tradeoffs inherent in cartograms have led to a wide variety of strategies, including manual methods and dozens of computer algorithms that produce very different results from the same source data. The quality of each type of cartogram is typically judged on how accurately it scales each feature, as well as on how (and how well) it attempts to preserve some form of recognizability in the features, usually in two aspects: [[shape]] and [[Geospatial topology|topological relationship]] (i.e., retained adjacency of neighboring features).<ref name="torguson2009">Dent, Borden D., Jeffrey S. Torguson, Thomas W. Hodler, ''Cartography: Thematic Map Design'', 6th Edition, McGraw-Hill, 2009, pp.168-187</ref><ref name="nusrat2015">{{cite journal |last1=Nusrat |first1=Sabrina |last2=Kobourov |first2=Stephen |title=Visualizing Cartograms: Goals and Task Taxonomy |journal=17th Eurographics Conference on Visualization (Eurovis) |date=2015 |arxiv=1502.07792 }}</ref> It is likely impossible to preserve both of these, so some cartogram methods attempt to preserve one at the expense of the other, some attempt a compromise solution of balancing the distortion of both, and other methods do not attempt to preserve either one, sacrificing all recognizability to achieve another goal.