Comparisons are extremely important for visual communication. Without comparisons we have no baseline about which we can make some sort of decision. When maps are involved, we often see areas that exhibit more, or less…or have values that are higher or lower. We sometimes use multiple maps to display how patterns have changed over time. There’s many techniques but the fundamental principle involves giving your map reader a basis for comparison to support their ability to assess what they are looking at relative to something else. Making the ‘something else’ familiar or understandable is crucial.
So if you were mapping the geography of the first moon landings by Neil Armstrong and Buzz Aldrin how do you give your reader a comparison given no-one, by definition, would ever (or are very unlikely ever) to have seen the place. The answer is to give them something that is familiar. The map presented here plots the various activities of the moon landing faithfully. It uses simple geometries that in themselves are understandable. Presenting the work atop a football pitch with its universally familiar markings is a clever approach. immediately, we have a sense of scale and extent. The football pitch is arguably the most internationally of sports and translates well with no other language or description necessary. The fact they gave it a strong colour and made it integral to the work also benefits the map. They could have used a faded outline but for comparison we need a strong visual.
An excellent use of a comparative symbol and extent to support the main map reading task.