Transcript Object-oriented Data Models

Designing Maps
GTECH201
Lecture 19
Yet Another Definition
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“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features have been replaced by symbols in their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.”
Cartographic Design Principles
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Audience and purpose
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Size, scale, and media
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Visual balance
Audience and Purpose
Size, Scale and Media
Visual Balance
Elements of a Map
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Map body
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Legend
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Title
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Scale
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North arrow
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(inset map)
Other Elements of a Map
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Source of data
Map projection
Author
Date
Neatline
Graphs, tables, images, informative text
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..leading towards a poster
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/
How accurate is it and where can you get it?
•Credits.
•How was it made.
•Projection and Datum.
•Other metadata
Map Templates
Layer Transparency
Labels and Annotation
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..more later today
Reference System
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Graticule ºN/S, ºE/W
Measured grid X, Y
Reference grid 12B or 14G
Map Layout
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Templates again
Map Scale
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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
Why Do We Care About Scale
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To compare or edge-match maps, they
must be in the same GCS
Remember, a GCS consists of:
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A metric
An origin
A projection
A datum
Types of Scale
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Graphical
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Phrase (word(y) statement)
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Representative fraction
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Special cases
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Variable scale
Graphical Scale
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Changes in map size(copy machine)
preserve scale relationships
Unit independent
Verbal Scale
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Does not preserve scale with size change
Unit-dependant
One inch equals one mile
One to a a mile
Representative Fraction
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Does not preserve scale in size change
Unit independent
Ratio is true regardless of units
Expressed as a ratio
1:100,000
Expressed as a fraction
1/100,000
Variable Scale
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Projections that do not preserve
distance
City maps (Falk)
Large vs. Small Scale
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Small scale shows large areas
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Large denominator 1/500,000
Think of it as small in detail
Large scale shows small areas
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Small denominator
1/500
Think of it as large in detail
Area and Scale
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Retains the same relationship as linear
scale
The linear scale is squared
2
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1:1,000 equals 1:1,000,000
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One square inch to one square mile
Examples
of Scale
You Have to Decide
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What is the intended use
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How will it be used
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How much detail
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What are the units
Linear Units
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Metric
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SAE
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Miles, yards, feet, inches
Other
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Kilo-, centi-, milli-meters
Degrees, chains, furlongs, rods, light-years
Unit-less
Areal Units
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Metric
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U.S. Public Land Survey
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Township, section, acre
Other
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Hectare, decare, are
City block, ZIP code, police district, parsec
Unit-less
Convenient Fractions
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Metric
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SAE
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1 / 100,000 or 1 cm equals 1 km
1 / 63,360 or 1 inch equals 1 mile
U.S. topographic maps
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1 / 24,000 or 1 inch equals 2,000 feet
Metric / SAE Conversion
League
Mile
Furlong
Chain
Rod
Yard
Foot
Link
Hand
Inch
Line
1
3
24
240
960
5280
15,840
24,000
47,520
190,100
2,281,000
Kilometer
4.828
Meter
4,828
Centimeter 482,800
Millimeter
4,828,000
Beware of
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1 / 100,000 does NOT mean
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1 mm equals 1 km, or
1 inch equals 100,000 feet
Mixed units
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Not allowed in representative fractions
Permitted in verbal usage
Resolution
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What is it that you wish to represent
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Countries
States
Counties
Towns
Property ownership
Detail
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How much information needs to be
conveyed?
How precisely have objects to be
mapped?
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Generalization
Cartographic license
Cartographic License
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Alteration of real-world spatial relations
to better present pertinent information
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Distortion
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Combination
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Shift
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Exaggeration
How Much Detail?
Road Displacement
Generalization
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1:5,000
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1:10,000