Cartographic Grammar and Vocabulary: Conventional Signs

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Cartographic Grammar and Vocabulary Conventional
Signs
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Conventional signs and symbols

• A map as a whole is a symbol of the real world
• Maps also contain smaller items which are
  themselves symbols of elements of the environment
• Environmental phenomena occur at points, along
  lines, or within areas
• Three classes of symbols are required to reflect
  these
• By adding a name a class symbol becomes a unique
  feature

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Conventional signs and symbols

• Symbols can tell us what the feature is
• Also
• Quantity, value, size, height, intensity, etc.
• Symbols can be
• Quantitative indicate value
• Qualitative no indication of value
• Arbitrary appearance unrelated to phenomenon
  shown
• Pictorial symbol suggests item shown
• Extensive system of conventional symbols
  developed over time to convey graphically the
  identity and location of phenomena

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Conventional Signs and Symbols

• Maps 2 dimensional attempts to illustrate 3
  dimensional phenomena
• Conventional signs attempt to reconcile
  difficulties of accuracy and visual effect that
  the transformation poses
• Mapmaker must maximize symbol-referent
  coordination make meaning clear without need to
  refer to legend

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Conventional Signs and symbols

• Ideally use symbols that reproduce pictorial
  image however in profile they are only two
  dimensional
• Encourages use of birds eye views (3
  dimensional)
• With gradual shift to vertical viewpoint and
  greater spatial accuracy, substitution of
  geometrical for pictorial symbols

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Conventional Signs and symbols

• Towns
• Early use of circle with dot or cross in centre
• Church typically used as symbol for towns in
  16th-18thC
• Hierarchy of own symbols seem to have developed
  in Germany in late 15thC

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John Norden 1595
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John Norden 1595
Peter Apian 1568
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Horwood 1799
Ordnance Survey 1878
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Conventional Signs and Symbols

• Relief
• Earliest representations sugarloaves, rope-like
  figures for mountain chains
• 16thC mountains typically shade on south-east
  side (hatching)
• Non-pictorial shading (hachures) appears in late
  18thC early hairy caterpillars evolve into
  complex patterning
• Concept of isolines introduced in early 18thC,
  contours introduced in 1749 by Milet de Mureau
• 1791 J.L. Dupain-Triel map of France with
  contours at 20m, hachures, spot heights and a
  vertical section

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Sanuto Abyssinia 1588
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Conventional Signs and Symbols

• Hachures (18thC)
• Lines running down direction of greatest slope
• Greater the slope, heavier the hachures, closer
  they are spaced (Lehman scale)
• Obscure details, hard to distinguish elevations
  from depressions

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Conventional Signs and Symbols

• Layer colouring/tinting
• different height levels indicated by different
  colours
• Rock drawing
• show summits, precipitous slopes, rock falls
• Spot heights
• first used on British maps by Christopher
  Packe in 1743
• Contours
• introduced on British maps in 1843 by the
  Ordnance Survey

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Conventional Signs and Symbols

• Sea and Land
• Various methods used to distinguish sea from land
• Sea left blank
• Line symbols (Ptolemy editions)
• Stippling (Ortelius)
• Outshore hatching (Blaeu, Coronelli)
• Elaborate patterning (Wagenhaer, Hondius
  shot-silk)
• Form lines (Popple)
• Colour (Ordnance Survey)

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Ptolemy Basle 1540
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Ptolemy Strassburg 1513
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Ptolemy Strassburg 1522
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Mercator Hondius 1606
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Conventional Signs

• Roads
• Roman Peutinger Table roads as single straight
  line segments
• British medieval strip map roads as straight,
  double, parallel lines
• German maps before 1500 use a single dotted line
• John Norden (1590s) first to include roads on
  English county maps uses double dotted lines
• John Ogilby 1675 double black lines if
  included by hedges, or prickd lines if open

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Peutinger Table 300 AD
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John Norden 1598
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John Ogilby 1675
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John Cary 1790