Designing Maps

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Designing Maps

• GTECH201
• Lecture 19

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Yet Another Definition

• A graphic depiction of all or part of a
  geographic realm in which the real-world features
  have been replaced by symbols in their correct
  spatial location at a reduced scale.

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Cartographic Design Principles

• Audience and purpose
• Size, scale, and media
• Visual balance

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Audience and Purpose
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Size, Scale and Media
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Visual Balance
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Elements of a Map

• Map body
• Legend
• Title
• Scale
• North arrow
• (inset map)

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Other Elements of a Map

• Source of data
• Map projection
• Author
• Date
• Neatline
• Graphs, tables, images, informative text
• ..leading towards a poster

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Who Made It?
UTM??
What is its name?
Coordinates in DD
Legend
Where is it located (inset)?
Border
Where is north
Neatline?
What is the scale/

• Credits.
• How was it made.
• Projection and Datum.
• Other metadata

How accurate is it and where can you get it?
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Map Templates
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Layer Transparency
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Labels and Annotation

• ..more later today

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Reference System

• Graticule ºN/S, ºE/W
• Measured grid X, Y
• Reference grid 12B or 14G

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Map Layout

• Templates again

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Map Scale

• The ratio of the distance between two points on
  the map and the distance between the same two
  points in the real world
• Describes distances and area sizes

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Why Do We Care About Scale

• To compare or edge-match maps, they must be in
  the same GCS
• Remember, a GCS consists of
• A metric
• An origin
• A projection
• A datum

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Types of Scale

• Graphical
• Phrase (word(y) statement)
• Representative fraction
• Special cases
• Variable scale

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Graphical Scale

• Changes in map size(copy machine) preserve scale
  relationships
• Unit independent

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Verbal Scale

• Does not preserve scale with size change
• Unit-dependant
• One inch equals one mile
• One to a a mile

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Representative Fraction

• Does not preserve scale in size change
• Unit independent
• Ratio is true regardless of units
• Expressed as a ratio 1100,000
• Expressed as a fraction 1/100,000

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Variable Scale

• Projections that do not preserve distance
• City maps (Falk)

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Large vs. Small Scale

• Small scale shows large areas
• Large denominator
• Think of it as small in detail
• Large scale shows small areas
• Small denominator
• Think of it as large in detail

1/500,000
1/500
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Area and Scale

• Retains the same relationship as linear scale
• The linear scale is squared
• 11,0002 equals 11,000,000
• One square inch to one square mile

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Examples of Scale
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You Have to Decide

• What is the intended use
• How will it be used
• How much detail
• What are the units

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Linear Units

• Metric
• Kilo-, centi-, milli-meters
• SAE
• Miles, yards, feet, inches
• Other
• Degrees, chains, furlongs, rods, light-years
• Unit-less

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Areal Units

• Metric
• Hectare, decare, are
• U.S. Public Land Survey
• Township, section, acre
• Other
• City block, ZIP code, police district, parsec
• Unit-less

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Convenient Fractions

• Metric
• 1 / 100,000 or 1 cm equals 1 km
• SAE
• 1 / 63,360 or 1 inch equals 1 mile
• U.S. topographic maps
• 1 / 24,000 or 1 inch equals 2,000 feet

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Metric / SAE Conversion
League 1
Mile 3
Furlong 24
Chain 240
Rod 960
Yard 5280
Foot 15,840
Link 24,000
Hand 47,520
Inch 190,100
Line 2,281,000
Kilometer 4.828
Meter 4,828
Centimeter 482,800
Millimeter 4,828,000
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Beware of

• 1 / 100,000 does NOT mean
• 1 mm equals 1 km, or
• 1 inch equals 100,000 feet
• Mixed units
• Not allowed in representative fractions
• Permitted in verbal usage

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Resolution

• What is it that you wish to represent
• Countries
• States
• Counties
• Towns
• Property ownership

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Detail

• How much information needs to be conveyed?
• How precisely have objects to be mapped?
• Generalization
• Cartographic license

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Cartographic License

• Alteration of real-world spatial relations to
  better present pertinent information
• Distortion
• Combination
• Shift
• Exaggeration

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How Much Detail?
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Road Displacement
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Generalization

• 15,000

• 110,000