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There are some (scientific) rules in map design but much artistic
judgement in terms of
◦ selection of colours
◦ symbology
◦ labelling (format and position)
◦ arrangement of overall layout
◦ (plus data selection, projection, scale, etc)
Subtle changes in design (e.g. weight of a label font for particular
objects) can yield big changes in how the map is read
Use (and mis-use) the power of design. ethical practices not to
deliberately deceive
1. Classification
2. simplification
3. symbolization
1. Map layout
2. Map scale and generalisation
3. Symbolisation and graphic variables
4. Choropleth mapping & data classification
5. Colour
6. Labelling and typography
For presentation of maps, some conventions on what to include:
◦ a title (or caption). clearly state what the map shows. plus relevant date of data, sources, missing values, author, contact info, etc
◦ a legend, so any reader can interpret the content of the map. meaning of all symbol and colours
◦ scale indication. translates distance on the map to distance on the ground
◦ orientation indication (the good old north arrow)
◦ borders and neatlines
1
1.618
what level of detail is shown
crucial to choose appropriate scale to work at
large scale map : small surface area in high detail (e.g. city plans)
small scale : large surface area in low detail (e.g. national road atlas)
scale represented as a statement (“one inch equals five miles”), a
graphical scale bar, (useful for measuring lengths), or as a
representative fraction (1:1250)
very few maps use scale consistently for every object
Key modes of
generalisation
• distortion is inherent,
inevitable, unavoidable
•may have to leave
features off the map
altogether
• avoid visual clutter,
balance content and
legibility
graphic language (of points, lines, polygon, icons and text) used to
represent ‘real’ features on the map
legibility (‘practical’)
harmonious (‘pretty’)
symbols can be iconic, geometric or abstract
symbol selection is creative aspect of design, wide choice and few
firm rules
symbols can have several different dimensions (properties or
characteristics) which encode meaning
symbols can have quantitative or qualitative meaning
shape, size, orientation
colour hue, colour value, colour saturation, pattern
and location of course
(Source: Larry Landweber, http://www.cs.wisc.edu/~lhl/maps/)
choro from choros (place) and pleth (value)
counterpart of histogram
aggregate data, usually ratio or percentage
data map for discrete spatial units
practical Issues
◦ choice of intervals - number and their breaks
◦ equal interval, equal share (quantiles), standard deviational, …
choice of colors
◦ important for perception of patterns
misleading role of area of spatial units
◦ larger areas “seem” more important
classification is a key method of abstracting reality into simplified
map
method of classification is important as effects ‘look’ of the map
classification scheme can easily be experimented with (manipulated?)
to give the pattern you want
classification should ‘match’ data distribution
number of classes. can reader interpret between them?
recommended max of 6
distribution of zones into classes
Same data plus
different classification
equal different looking
choropleth map!
• natural breaks
(Jenks method)
• quantiles
• equal interval
• standard deviation
colour is one of most exciting aspects of design
colour perception is a combination of physiological
(sensing in the eye and cognitive processing) and
psychological reactions
colour evoke emotions. subjective reaction to colour
connotative meanings of colour. See Dent (1999, page
295)
cultural specific. also colour blindness. 7% of men and
1% of women
warm colours (red, orange, yellows)
cool colours (violet, blue, greens
defining - hue, saturation, value (HSV) model
hue - basic colour we
perceive, eg 12 step
Wheel
saturation - intensity or
purity compared to a
neutral gray
value - lightness or
darkness. Can be hard
to perceive variations
in value
gives structure and readability
developing figure and ground relationships
◦ warm colour better for figures. Said to ‘advance’ to viewer.
Cool colours tend to recede
perceptual grouping of like features through colour
colour contrasts. using value or saturation to represent data on
thematic maps
qualitative conventions - blue for water, green for lush
vegetation; red = warm and blue = cool in temperatures; hill
shading
lettering choice can have a significant impact to effectiveness of the map
map text to label features has several key parameters
◦ font typeface, size spacing
◦ placement and orientation
importance of type discernibility
map labels can communicate important data, e.g. hierarchy of features,
implying importance
Chislehurst, Bromley, L O N D O N
manual labelling of features can get very tedious. but automatic label
placement is still far from perfect
Think about different types of lettering styles and
placement/orientations used and the effects it has
◦ legibility of individual letters is of paramount importance, especially
in smaller type sizes. Choose a typeface in where there is little
chance of confusion between c and e and i and j
◦ select a typeface with a relatively large base height
◦ avoid extremely bold forms
◦ choose a typeface that has softer shading; extreme vertical shading
is more difficult to read than rounder forms
◦ do not use decorative typefaces on the map as they are difficult to
read
1. always have a straightforward agenda, and have a defining purpose or
goal for each map
2. always strive to know your audience, the potential/likely map users
3. do not intentionally lie with data
4. always show relevant data whenever possible
5. data should not be discarded simply because they are contrary to the
position held by the cartographer
6. at a given scale, strive for an accurate portrayal of the data
7. the cartographer should avoid plagiarizing; report all data sources
8. symbolization should not be selected to bias the interpretation of
the map
9. the mapped result should be able to be repeated by other
cartographers
10. attention should be given to differing cultural values and
principles
◦ Borden Dent, (1995) Cartography: Thematic Map
Design, fifth edition
◦ Terry Slocum, (1999) Thematic Cartography and
Visualization
◦ Menno-Jan Kraak and Ferjan Ormeling, (1996)
Cartography: Visualization of Spatial Data
