ENV103 Chap.3 Maps as Messengers: Cartographic Design
Maps as Messengers: Cartographic Design
Maps are constructions of a view of the world, not neutral copies of it. This chapter covers three working definitions of a map, the questions maps answer, the taxonomy of reference and thematic maps, the five cartographic steps from purpose to layout, and the design principles of visual weight, focus and the optical centre that decide where a reader's eye goes first.
A critique of a flawed draft shows how to fix centring, labelling and missing elements before a map is submitted, which matters most for the poster's design criterion.
What this chapter covers
- 01
Maps as constructions, not reconstructions
- 02
Reduced, selective and symbolised
- 03
Where, what, how much, which and when
- 04
Tangible, virtual and mental maps
- 05
Reference maps and thematic forms
- 06
Five cartographic steps
- 07
Visual weight and the optical centre
Worked example · free
Place the map body and the required elements on the page
- +1Find the geometric centre where the page diagonals cross, then place the map body slightly above it, at the optical centre where the eye lands first.
- +1Put the title at the top so it is read before anything else.
- +1Group the legend and scale bar along the lower edge, where they support the map without competing with it.
- +1Place the north arrow in a quiet corner and check the visual weight: bright or isolated elements draw attention, so keep secondary items muted.
Key terms
- Thematic map
- A thematic map selects one theme, such as density or vegetation, and displays it deliberately.
- General reference map
- A general reference map shows many kinds of features for a wide range of uses.
- Choropleth map
- A choropleth map fills defined areas with colour according to a value or category for each area.
- Cartogram
- A cartogram distorts the size of areas in proportion to a mapped value such as population.
- Optical centre
- The optical centre is the point slightly above the geometric centre where a viewer's eye first lands.
- Visual weight
- Visual weight is the attention an element attracts through its colour, size, contrast and isolation.
- Generalisation
- Generalisation is the deliberate simplification of map data through selection, classification, simplification and symbolisation.
Maps as Messengers: Cartographic Design FAQ
What does it mean that maps are constructions?
A map is made by someone for a purpose, so every map selects some features, leaves others out and symbolises what remains. It presents a view of the world rather than reproducing it. Recognising that helps you read maps critically and explain your own design choices honestly.
Which elements does every lab map need?
The lab rubrics repeatedly require a title, a legend, a scale bar and a north arrow, and usually your name. The lecture's longer list adds a neat line, the principal map body, ancillary text and metadata where useful. Missing a mandatory element is the easiest mark to lose.
How do I choose between a choropleth and a graduated symbol map?
Use a choropleth for rates or categories attached to areas, such as people per square kilometre by suburb. Use graduated or proportional symbols for totals at locations, such as the number of people near each volcano. Mapping raw totals as a choropleth exaggerates large areas.
What does generalisation involve when making a map?
Generalisation is the fourth of the lecture's five cartographic steps. It abstracts the data through selection, choosing which features appear; classification, grouping values; simplification, smoothing geometry such as coastlines; and symbolisation, choosing the visual variables. Each step removes detail on purpose so the map can carry its message at the chosen scale.
Assessment move
Treat this chapter as a checklist you will apply to every map you submit. Copy the five cartographic steps onto a card: purpose, scale, format, generalisation and layout. Before each lab map, write one sentence for the first step, because a map without a stated purpose usually ends up cluttered.
Learn the three definitions of a map by their key words, constructed, reduced, selective, symbolised and interface, since short-answer and quiz questions often turn on them. For the taxonomy, sketch a small example of each thematic form, choropleth, dot density, graduated symbol, flow line, isoline, cartogram and heatmap, and note the type of data each needs.
When you critique your own drafts, ask three questions in order: where does the eye go first, is that the message, and is every mandatory element present and readable at print size? Compare your answers with the visual-weight rules from the lecture, red over blue and isolated over crowded.
The poster rubric gives its largest share of points to presentation and geospatial design, so the time you put into these habits is repaid directly when the group’s layout is assessed.