introduction to mapping sciences: lecture #6 (creating maps in gis) making maps with gis the parts...
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Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Making Maps with GIS
• The Parts of a Map
• Choosing a Map Type
• Designing the Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
What is a map?
• “A graphic depiction of all or part of a geographic realm in which the real-world features have been replaced by symbols in their correct spatial location at a reduced scale.”
power line
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map functions in GIS
• Storage
• Temporary communication
• Intermediate check of data
• Final report
• To be effective, must be correctly designed and constructed.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
The Parts of a Map: Map Elements
The United States of America
Alaska
Lambert Conformal Conic ProjectionSource: U.S. Dept. of State
0 41 2 3
hundreds ofkilometers
0 4 0 4
Washington,D.C.National Capital
Legend
Scale
CreditsNorth ArrowPlace nameInset
Ground
Figure
Neat line Border Title
Hawaii
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Cartographic Elements
• Border• Neatline• Insets
– Scale up– Scale down
• Metadata e.g. index• Off-map references
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Cartographic Elements
• Page coordinates
• Ground elements
• Graticule/Grid
• North arrow
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Cartographic Elements
• Figure– Point/Line/Area symbols
– Text
– Place Names
– Title
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Cartographic Elements
• Reference Information– Scale
– Projection(s)
– Sources (2)
– Credits
– Legend
– Reliability
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map “impact”
• Distribution of Employment by State 1996
• USA: Employment Distribution 1996
•U.S. Employment: 1996 Distribution
• America at Work
• Where the Jobs are Today
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Text: Selection and Placement
New York
BM 232
US Route
66
200
L a
ke
M u d
POINT LINE AREAC
A
NV
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Choosing Elements
• Map research
• Map compilation
• Worksheet
• Selection
• Placement
• Layout
• Tools in GIS not ideal
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Choosing a Map Type
• Cartographers have designed hundreds of map types: methods of cartographic representation.
• Not all GISs allow all types.
• Most have a set of basic types
• Depends heavily on the dimension of the data to be shown in the map figure.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Choosing the Wrong Type
• Fairly common GIS error.
• Due to lack of knowledge about cartographic options.
• Can still have perfect symbolization.
• Possibility of misinformation
• Definite reduction in communication effectiveness.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map Types: Point Data
• Reference
• Topographic
• Dot
• Picture Symbol
• Graduated Symbol
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Mapping features conceived of as points
• Conceived spatial structure– exist as points– are referenced to points – are conceived of as points for mapping
purposes
• Levels of measurements – qualitative -- nominal– quantitative -- ordinal, interval, or ratio
• Symbolized with point marks
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Symbolizing qualitative point data
• Show the location of features without implying a message of magnitude
• nominal scale data• appropriate visual variables
– differentiating primary variables• shape• hue• orientation
– can you use secondary variables?• Pattern arrangement, pattern orientation
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Qualitative point maps
• Examples– hue– shape– orientation– pattern arrangement– pattern orientation
highly pictoralgeometric symbols mimetic symbols
Level of generalization
Qdx u v w
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Symbolizing quantitative point data
• Show the location of features while implying a “message of magnitude”
• ordinal, interval, ratio scale data
• appropriate visual variables– ordering primary variables
• size• value• chroma
– can you use secondary variables?
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Quantitative point maps
• Examples– Size
– Value
– Chroma
– Pattern texture
– Combinations:size and value
(Usually used together)
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Graduated Symbol Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Graduated symbol maps -- objective
• Also called “proportional symbol” maps• Symbol size varies from place to place in
proportion to the quantity it represents• Two types
– proportional -- size represents actual data values
– Classed – size represents classes of values• range graded -- size class represents a numeric
range of data (e.g., 1-10, 11-20, 21-30, 31-40, 41-50)
• ordinally scaled -- size class represents a descriptive group (e.g., low, medium, high)
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Graduated symbol maps – methods
• Graduated circles often used because of– compact geometric form– ease of scaling– visual stability (less eye wandering)
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Scaling Graduated Symbol Maps• Scaling determines the size of the symbols• Adjustments to scaling are sometimes made
– area is increasingly underestimated as higher magnitudes of the stimulus are judged
• Therefore, symbol sizes are adjusted to compensate for underestimation
• Methods for scaling circles– Square root method -- based on the area of the circle– Psychological scaling -- scales to reflect
underestimation by map users Values Radii500,000 1.58250,000 1.12100,000 0.71 50,000 0.50
Values Radii500,000 1.86250,000 1.25100,000 0.74 50,000 0.50
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Graduated symbol maps -- methods
1. Create area proportional circles using the circle radius equation
2. Scale circle area to square root of the data or scale proportional symbols to accommodate human perception of symbols
3. Couple size with another ordering visual variable (value)
4. Show a second distribution with another ordering visual variable (value)
5. Provide legend for symbology
500,000250,000100,00050,000
250,000 to 500,000100,000 to 250,00050, 000 to 100,0000 to 50,000
very largelargemediumsmall
500,000250,000100,00050,000
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Picture Symbol Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map Types: Line Data
• Network
• Flow
• Isopleth
• Reference
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
General Purpose: Reference Maps
• Network map– shows set of connected lines w/similar
attributes e.g., subway, bus/airline routes, streams/rivers
• Flow map– similar to network map, but line width varied
to show value
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Simple Flow Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Flow Map with Graduated Symbol
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map Types: Area Data
• Choropleth
• Area qualitative
• Stepped surface
• Hypsometric
• Dasymetric
• Reference
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Thematic Maps
• Choropleth map– data classified and grouped within areas such
as states or counties; shaded according to value
• Area qualitative map– simple color or pattern applied to area types
e.g. land use classes: residential, agricultural, forest, wetland, tundra, water
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Choropleth Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Area Qualitative Map: Land Use
Area Qualitative Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map Types: Volume Data
• [Isopleth, Stepped Surface, Hypsometric]
• Gridded fishnet
• Realistic perspective
• Hill-shaded
• Image map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Volumetric Data Maps
• Stepped statistical surface– block type diagram in perspective
• Isoline map– consists of lines joining points of equal value;
surface continuity is assumed
• Contour interval map (contour map)– isoline map indicating terrain changes; e.g.,
meters or ft between contour lines
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Stepped Statistical Surface Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Colored Isoline Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Shaded Contour Map
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Choosing Types
• Check the data– Continuous– Discrete– Accuracy & Precision– Reliability
• Dimension (Point, Line, Area, Volume)• Scale of Measurment (Nominal etc.)• GIS capability• May need to supplement GIS software
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Data Scaling (Stevens)
• Nominal (Name of a place)
• Ordinal (Small, med., large town)
• Interval (Arbitrary zero e.g. Sea Level)
• Ratio (Absolute zero e.g. dollars, densities)
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Example: Choropleth Mapping
• Data should be AREA (e.g. States)
• Data should not suffer from area effect.
• Population?
• Per capita Income?
• Elevation? Temperature?
• Boundaries unambiguous.
• Areas non-overlapping.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Classification
• Equal Interval
• Natural groups
• N-tiles
• Equal or unequal?
• Logarithmic? Linear? Discontinuous?
• How many classes?
• Non-overlapping, distinctive groups.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
The Need for Design
To appear professional and avoid errors, GIS maps should reflect cartographic knowledge about map design.
A map has a visual grammar or structure that must be understood and used if the best map design is desired.
Cartographic convention (e.g. forests should be green).
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map Design
• A GIS map is designed in a process called the design loop.
• Good map design requires that map elements be placed in a balanced arrangement within the neat line.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
The Design Loop
• Create map layout as macro
• Draw on screen (proof plot)
• Look
• Edit macro
• Repeat until happy
• Make final plot
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Graphic Editors
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Graphic Editor Software
• Vector– Adobe Illustrator– CorelDraw– Freehand
• Raster
– Photoshop– CorelPaint– Fractal Paint
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map Design (2)
• Visual balance is affected by:
• the "weight" of the symbols
• the visual hierarchy of the symbols and elements
• the location of the elements with respect to each other and the visual center of the map.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Visual center
5% of height
5% of height
Landscape Portrait
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Visual Layout
Title Here
Title Here
Eye expects (1) balance and (2) allignment
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Symbol “weight”
Line weight Pattern Shading Hue
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Color and Map Design
• Color is a complex visual variable and in a GIS is specified by RGB or HSI values.
• Red, Green, Blue are additive primaries.
• Magenta, Cyan and Yellow are subtractive primaries.
• Saturation and Intensity map better onto values than hue.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Dimensions of Color
HUE
SATURATION
INTENSITY
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Simultaneous Contrast
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Color Primaries
Subtractive color Additive color
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Text placement
Santa BarbaraSanta Barbara
Santa Barbara
Santa Barbara
L a g o o n
Path right
Path Down
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Scale and Generalization
• Smaller scale means fewer features.
• Smaller scale means smoother features.
• Smaller scale means combining features.
• Smaller scale means displacing features.
• Often scales are mixed or overgeneralized.
Introduction to Mapping Sciences: Lecture #6 (Creating Maps in GIS)
Map Design and GIS
• When a GIS map is the result of a complex analytical or modeling process, good design is essential for understanding.
• The map is what distinguishes GIS as a different approach to the management of information, so extra care should be taken to improve the final maps that a GIS generates in a GIS task.