Working with Map Projections-A Guide to their Selection

319 Pages·2019·185.524 MB·\319

by  Fritz Kessler (Author), Sarah Battersby (Author)

Working with Map
Projections
A Guide to Their Selection

Working with Map
Projections
A Guide to Their Selection
Fritz C. Kessler and Sarah E. Battersby
CRC Press
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Contents
Contents
This book is dedicated to John Snyder and Waldo Tobler, two giants in
the map projection field who did much to inspire the present work.

Contents
Preface ...................................................................................................................xiii
Acknowledgments ................................................................................................xv
Authors ................................................................................................................xvii
Part I Projection Basics, Cartographic Symbolization,
Projection Influences on People’s
Mental Maps, and Selecting Projections
1. Introduction .....................................................................................................5
Mathematical Complexity ..............................................................................5
Thread 1: Ellipsoid vs. Sphere Earth Models ..........................................6
Thread 2: Projection Parameters ...............................................................7
Map Projection Terminology .........................................................................8
Scattered Map Projection Literature ...........................................................11
Map Projections as a Map Design Variable ................................................12
The Problem of Selecting a Map Projection ...............................................15
This Book’s Structure ....................................................................................16
2. A Gentle Introduction to Map Projections ..............................................19
Earth’s Latitude and Longitude ...................................................................20
Earth’s Shape and Size ..................................................................................22
The Map Projection Process .........................................................................26
Projection Equations .................................................................................27
Spherical vs. Ellipsoidal Projection Equations ..........................................31
The Map Projection Properties ....................................................................31
Preserving Angles (Conformal Property) .............................................32
Preserving Areas (Equal Area Property) ..............................................33
Preserving Distances (Equidistant Property) .......................................35
Preserving Directions (Azimuthal Property) .......................................38
Preserving No Specific Property (Compromise) ..................................38
Projection’s Influence on Map Design ........................................................40
The Map’s Shape: The Projection Class ..................................................40
Focusing the Map’s Center: The Projection Aspect ..............................42
Map Projection Distortion ............................................................................43
Distortion Patterns and Projection Class ...............................................43
Distortion Patterns and Projection Property ........................................45
Distortion Patterns and Standard Point or Line(s) ...............................48
vii
viii Contents
Distortion Impacts on Shapes of Landmasses ......................................52
Conclusion ......................................................................................................55
Notes ................................................................................................................56
3. Representing Spatial Data through Cartographic Symbolization .....59
Types of Maps .................................................................................................60
The Map Abstraction Process ......................................................................61
Conceptualizing Earth’s Geographic Phenomena ....................................64
Spatial Dimensions ...................................................................................64
Typology of Geographic Phenomena .....................................................65
Levels of Data Measurement ...................................................................67
Visual Variables .........................................................................................69
Shape ...........................................................................................................69
Hue ..............................................................................................................69
Orientation .................................................................................................72
Pattern .........................................................................................................72
Hue ..............................................................................................................74
Value ............................................................................................................75
Saturation ...................................................................................................75
Size ..............................................................................................................76
Cartographic Symbolization Methods ........................................................76
Choropleth .................................................................................................76
Dot Density ................................................................................................77
Proportional Symbol .................................................................................77
Isarithmic ...................................................................................................78
Dasymetric .................................................................................................79
Cartogram ..................................................................................................81
Map Reading Tasks ........................................................................................81
Pre-Map Reading ......................................................................................83
Detection and Recognition ......................................................................84
Estimation ..................................................................................................85
Conclusion ......................................................................................................87
4. Map Projections’ Influence on Data Representation ............................91
Interpreting Map Projections .......................................................................92
The Edge of the Map (Periphery) .................................................................98
Long-Term Impacts of Map Projection? ....................................................100
Does the Projection Look “Right” or “Wrong”? ......................................102
Is the Overall Shape Appealing? ...............................................................105
Aesthetics and Fit .........................................................................................108
Conclusion ....................................................................................................109
Contents ix
5. Assistance Using Projection Selection Guidance Tools .....................113
Projection Properties of Importance .........................................................114
Geographic Location, Size, and Shape ......................................................118
Broader Design and Analytic Considerations .........................................123
Projection Shape ......................................................................................123
Arrangement of the Graticule ...............................................................125
Appearance of the Poles .........................................................................129
Interpretability ........................................................................................131
Conclusion ....................................................................................................133
Part II Projection Selection by Map Type
6. Continuously Occurring and Abruptly Changing ..............................141
Visual Analysis Tasks ..................................................................................142
Impact of Projection on Choropleth Maps ...............................................143
Equal Area Projections ...........................................................................143
Conformal Projections ............................................................................147
Equidistant Projections ..........................................................................147
Compromise Projections ........................................................................147
Large-Scale Projections ..........................................................................148
Conclusion ....................................................................................................149
7. Continuously Occurring and Smoothly Changing .............................151
Visual Analysis Tasks ..................................................................................153
Spatial Interpolation: An Initial Step in Isarithmic Mapping ...............154
Impact of Projections on Calculating Values for Isarithmic Maps .......156
Distance Measurements .........................................................................158
Datum and Grid Systems .......................................................................160
Equidistant Projections ..........................................................................161
Conformal Projections ............................................................................163
Spatial Interpolation Results .................................................................164
Impact of Projection on Design for Isarithmic Maps..............................165
Equidistant Projections ..........................................................................168
Conformal Projections ............................................................................169
Equal Area Projections ...........................................................................171
Compromise Projections ........................................................................175
Conclusion ....................................................................................................176
Notes ..............................................................................................................177
8. Discretely Occurring and Smoothly Changing ...................................179
Visual Analysis Task ...................................................................................181
Impact of Projection on Dot Maps .............................................................182