Map Understanding

1
Map Understanding

• Overview of Lecture
• Definitions
• Purpose of maps
• Types of maps
• Map compilation

2
Definitions What is a Map?
Map Understanding

• General
• Specific

3
Why Consider Maps?
Map Understanding

• Why use maps?
• Why are maps important in GIS?

4
Types of Maps
Map Understanding

• Common classifications

5
Distinction of Horizontal and Vertical
Map Understanding
Horizontal
6
Planimetric Maps
Map Understanding

• Characteristics
• Usage

7
Topographic Maps
Map Understanding

• Characteristics
• Methods used to represent vertical

8
Topographic Maps Contours
Map Understanding

• Definition
• Advantages of contours

9
Thematic Maps
Map Understanding

• Characteristics
• May display
• Use symbology

10
Map Compilation
Map Understanding

• Definition
• Techniques
• Issues with using existing data for map
  compilation

11
Cartographic Abstraction
Map Understanding

• What is cartographic abstraction?
• Why is there a need for abstraction?
• Components of abstraction
• Selection Classification
• Exaggeration Symbolization
• Simplification/combination

12
Cartographic Abstraction
Map Understanding

• Selection
• Classification
• Exaggeration

13
Cartographic Abstraction
Map Understanding

• Symbolization
• Simplification/Combination

14
Images vs. Maps
Map Understanding

• Aerial photographs are not maps
• Photographs do not have
• Orthophotos remove effects of

15
Map Issues
Map Understanding

• Maps are selective
• Maps are always out of date
• Compilation is imperfect

16
Readings
Map Understanding

• Chapter 3 Sections 3.7, 3.8
• Chapter 4 Box 4.3
• Chapter 12 Sections 12.1 12.3

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18
Map Analysis

• Applications
• Inventory
• Overlay
• Overview of lecture
• Map projections
• Map scale
• Map accuracy
• Map interpretation

19
Map Projections
Map Analysis

• Issue
• Projections provide
• The projection process (conceptually)

20
Map Analysis
Developable surfaces
21
Map Analysis
Developable surfaces
22
Developable surfaces
Map Analysis
23
Projection Equations
Map Analysis

• Assume one-to-one correspondence between
• Inverse equations also exist

24
Issues with Map Projections
Map Analysis

• Challenges
• Aim to preserve some characteristic

25
Conformal Projections
Map Analysis

• Characteristics
• Issues

26
Equivalent Projections
Map Analysis

• Characteristics
• Issues

27
Other Projections
Map Analysis

• Equidistant projections
• Direction preserving projections

28
Example Equations Mercator Conformal Projection
Map Analysis

• Direct equations
• x ? y ln tan(?/4 ?/2)
• Inverse equations
• ? x ? 2 tan-1ey ?/2
• Complications

29
Projections in GIS
Map Analysis

• Coordinate systems
• Later

30
Map Scale
Map Analysis

• What is scale?

• Representing Scale
• Numerical
• Graphical

0
50
50
100
150
200
250 km
31
Map Scale in GIS
Map Analysis

• Scale is reduction factor relating reality to map
• Determining unknown scale
• Issue

32
Map Accuracy
Map Analysis

• Types of errors in maps
• Positional errors
• Attribute errors
• Potential sources of error

33
Map Interpretation
Map Analysis

• Direction
• Distance
• Area
• Elevation
• Symbols and Legends

34
Map Interpretation Direction
Map Analysis

• Types of direction
• Expressing direction

35
Azimuth
Map Analysis
36
Bearing
Map Analysis
37
Compass Rose
Map Analysis
38
Map Interpretation Distance
Map Analysis

• Direct distance measurement
• Indirect measurement Coordinates

39
Map Interpretation Area
Map Analysis

• Measuring Area
• Areal scale

40
Map Interpretation Elevation
Map Analysis

• What is elevation?
• Displaying elevation
• Derivatives of elevation

41
Map InterpretationSymbols and Legends
Map Analysis

• Cartographic abstraction ? symbolization
• Legend
• Symbols vary

42
Readings
Map Analysis

• Chapter 5 Sections 5.6, 5.7