What is a cartogram used for?

What is a cartogram used for?

Cartograms are used for thematic mapping. They are a particular class of map type where some aspect of the geometry of the map is modified to accommodate the problem caused by perceptually different geographies.

What is a cartogram in GIS?

A cartogram is a map on which statistical information is shown in diagrammatic form. The geometry is often extremely distorted to show a variable using the polygon’s area. Two cartogram representations of the US –with distorted area (left) and equal area (right).

How does a cartogram distort the map?

Cartograms exaggerate the size of the geography proportional to the statistic being shown. Specifically, the variable substitutes land area or distance. But what they do is really distort our view of mapping by breaking the golden rule – sacrificing geometry to convey information.

How does a cartogram depict information?

A cartogram is a type of graphic that depicts attributes of geographic objects as the object’s area. Because a cartogram does not depict geographic space, but rather changes the size of objects depending on a certain attribute, a cartogram is not a true map.

What does a cartogram map look like?

A cartogram is a map in which the geometry of regions is distorted in order to convey the information of an alternate variable. Most of the time, a cartogram is also a choropleth map where regions are colored according to a numeric variable (not necessarily the one use to build the cartogram).

What does a cartogram not represent?

Since the cartogram does not represent geographic space, but alters the size of objects in proportion to an attribute, it is not considered a scaled map. As such, the cartogram does not always appear visually similar to a map. Cartograms are of three types: noncontiguous, contiguous, and Dorling cartograms.

What is the difference between a cartogram and Choropleth?

Choropleth maps show us how much geographic area is affected. On some maps, this means that large regions where only a few people take up a lot of space on the screen. Population cartograms, on the other hand, drive more attention to populated areas.

What do cartograms preserve?

Cartogram maps retain a partially accurate relative location and relative space, but the actual area of the individual polygons features are overrepresented or underrepresented based on the assigned values.

What are population cartograms?

If we want to show where the world’s people are we need a population cartogram, a geographical presentation of the world where the size of the countries are not drawn according to the distribution of land, but according to the distribution of people.

What is an area cartogram in geography?

Area cartograms. An area cartogram is sometimes referred to as a value-by-area map or an isodemographic map, the latter particularly for a population cartogram, which illustrates the relative sizes of the populations of the countries of the world by scaling the area of each country in proportion to its population;

What are map projections in geography?

Map makers attempt to transfer the earth—a round, spherical globe—to flat paper. Map projections are the different techniques used by cartographers for presenting a round globe on a flat surface. Angles, areas, directions, shapes, and distances can become distorted when transformed from a curved surface to a plane.

Can I present my data as a cartogram?

If it is an acceptable visualization for your dataset, then you can present your data as a cartogram. Otherwise, please choose a different dataset to continue. Your map is ready! Liked our work? Make sure to credit us using the citation below: Gastner MT, Seguy V, More P. Fast flow-based algorithm for creating density-equalizing map projections.

What is van der Grinten’s map projection?

Alphons J. van der Grinten developed a map projection that was neither conformal nor equal-area. The Van der Grinten map projection is a compromise projection showing the entire earth within a circle. Shape and size distortions increase away from the central section, particularly in the high latitudes.