Map fact/Map fiction

“A map that did not generalize would be useless” (Monmonier)

By using the process of generalization to create a map are you changing the facts and turning your map into fictional map? Are all maps then fictional?

Generalization is part of the map abstraction process that involves “removing details from object and phenomena to be maps.” (Lecture slideshow geog 312)

When a cartographer is creating a map they need to decide on how much detail to include on the map. If the maps has too much detail then is will be cluttered with unnecessary detail that map take away from the purpose of the map. On the other hand if a map is over generalized then the map will be useless and unable to transfer the information. A cartographer needs to find a balance with how much to generalize.

There are five main types of generalization, selection, simplification and smoothing, displacement, enhancement and displacement conversion.

Selection involves deciding on what the cartographer wants to map. Decisions on the “geographic space to be mapped, map scale, map projection and aspect, which data variables are appropriate for the maps purpose” (Dent 16) need to be made. The cartographer may choose specific details that skew the actual facts of the map. For example if the cartographer is creating a map to answer a question like, there are more rivers in Nevada then in Utah. The cartographer may only choose to map major rivers in Utah and then every river in Nevada. Then the map shows that there are more rivers in Nevada even though there may be more rivers in Utah. Everything on the map is fact but because the cartographer only chose specific things to go on the map to prove the point, the map then is fictional because it is not showing the data accurately or unbiased.

Simplification and smoothing is the process of removing detail and angularity from the objects and phenomena to be mapped. Simplification is removing detail from particular features such as a line. By removing the detail you are now making the map fictional because it changed the shape of the line. Smoothing also takes away the true form of a line.

Displacement is moving features on a map apart so they do not interfere with each other. If a feature is moved from the exact location then it is not longer true.

The generalization process is not the only process that makes all maps fictional.

The earth is round and most maps are flat, so the process of taking features for the round earth and projecting them onto a flat surface. There are several different types of projections are each one distorts the shape of the earth differently. Depending on the geographic area that you are mapping depends on the projection that you choose.

In thematic mapping, choosing a classification class can change the out put of the data also my choosing a small number of classes in a choropleth map will over generalize and will not show the accurate special patterns. The image below show the difference when you choose 2, 5, and 9 classes. Each map uses the same data which is fact but when the data is represented it is skewed and can become fictional.

The three maps above all use the same data by they use different ranging method. Are all of the maps true or fact or are they fictional? The equal step map doesn’t show the true special relationship of the data so it is fictional. The quintile range best represents the data set by it is still only a general overview of the data set.

Even though maps are generally fictional they still have value, they do represent a generalization of the truth, which is usually enough to show the special information.