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Government 90dnMapping the Census

Lecture 5: Cartography

Sumeeta Srinivasanssrinivasan@cga.harvard.edu

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OutlineMap AudiencesVector GIS representationGraphic Elements based on vectorsColorsGraphical HierarchyMap Types

Normalizing DataMap Layouts

Exporting Maps

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Map AudiencesMap Use: Exploration PresentationAudience: Trained Analyst General Public

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Map AudiencesMap Use: Exploration PresentationAudience: Trained Analyst General PublicPurpose: Visual Thinking Communication

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Map AudiencesMap Use: Exploration PresentationAudience: Trained Analyst General PublicPurpose: Visual Thinking Communication

Advantages: Graphical Believable

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Map AudiencesMap Use: Exploration PresentationAudience: Trained Analyst General PublicPurpose: Visual Thinking Communication

Advantages: Graphical Believable

Granularity: Fine Coarse

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Map AudiencesMap Use: Exploration PresentationAudience: Trained Analyst General PublicPurpose: Visual Thinking Communication

Advantages: Graphical Believable

Granularity: Fine Coarse

Symbols: Abstract Mimeticcapital

railroad

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Vector GISPoint

Line

Polygon

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PointsData Attached to Points

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PointsSame data displayed as different points

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Lines

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PolygonsPoint

LinePolygons

GreenSpaces

Buildings

Census

Blocks

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Jacques Bertin

What should

be

printed

to

facilitate

communication,

that

is, to tell others what we know without a loss of information

Jacques Bertin, Paris, February 1983

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Bertins Graphic Variables

Saturation

Value Hue

More Value

Shape

Texture Size

Orientation

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Saturation

Value Hue

More ValueTexture

Orientation

Size

ShapePoint Symbols

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Use Solid Point Markers

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Use Three to Seven Categories Max

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Saturation

Value Hue

More Value

Shape

Texture Size

OrientationOrientation

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Saturation

Value Hue

More Value

Shape Orientation

SizeTexture

Texture

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Texture

Black and White PrintsPolygonsLarge Areas

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TextureBrings object to the front (figure)

long wavelength huescoarse texture

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Saturation

Value Hue

More Value

Shape

Texture

Orientation

Size0-25

4-9>9

Size

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SizeGraduated SymbolsShow Size or Amount

Elevated Blood Level

!( 26 - 50

!( 51 - 150

!( 1 - 25

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Shape

Texture

Orientation

Size Saturation

Hue

More Value

ValueValue

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ValueIncrease/Decrease Contrast

The greater the difference in value between an

object and its background, the greater thecontrast

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Value

By creating a pattern of dark to light values, evenwhen the objects are equal in shape and size, itleads the eye in the direction of dark to light

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Value

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Value

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Shape

Texture

Orientation

Size Saturation

Value

More Value

HueHue

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Shape

Texture

Orientation

Size Saturation

Value Hue

More Value

Value

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Shape

Texture

Orientation

Size

Value Hue

More Value Saturation

Saturation

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SaturationYou can change the saturation of a hue by adding black(shadow) or white (light). The amount of saturation gives

us our shades and tints.

Percentage Female-HeadedHouseholds with Children

0% to 4%

4% to 8%

8% to 12%

Greater than 12%

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SaturationCustomize the Propertiesof a layer

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Color Hues and ValuesEach of individual color is a hueColors have meaning (i.e. cool colors, warm colors, etc)

-Cool colors calming

-Warm colors exciting-Cool colors appear smaller than warm colors and theyvisually recede on the page so red can visually overpower

and stand out over blue even if used in equal amountswww.colormatters.comwww.colorbrewer.org

http://www.colormatters.com/http://www.colorbrewer.org/http://www.colorbrewer.org/http://www.colormatters.com/

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Color Wheel redviolet

blue

orange

yellow

green

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Color WheelHarmonytwo adjacent hues

red

violet

blue

orange

yellow

green

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Color WheelHarmonytwo adjacent hues

red

violet

blue

orange

yellow

green

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Color WheelHarmonytwo adjacent hues

red

violet

blue

orange

yellow

green

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Color WheelHarmonytwo adjacent hues

Contrasttwo hues with

one hue skippedin between

red

violet

blue

orange

yellow

green

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Color WheelHarmonytwo adjacent hues

Contrasttwo hues with

one hue skippedin between

red

violet

blue

orange

yellow

green

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Color WheelHarmonytwo adjacent hues

Contrasttwo hues with

one hue skippedin between

red

violet

blue

orange

yellow

green

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Color WheelHarmonytwo adjacent hues

Contrasttwo hues with

one hue skippedin between

red

violet

blue

orange

yellow

green

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Non-Contrasting vs. Contrasting

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Color WheelHarmony

two adjacent huesContrast

two hues withone hue skippedin between

ClashOpposites

red

violet

blue

orange

yellow

green

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Double-Ended ScalesExtremes Emphasized

critical value of zeroregression residuals, time changeblue and red contrastwhite center is ground

-4 to -2-2 to 2

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Change Map Example

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Color Spot

0802

0604

0605

0507 0810

0804

0809

0903

White background allows yellow color spot to be visualized

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Color Spot Ramps

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Graphical HierarchyGoaldirect attention toward or away from available Information

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Graphical HierarchyGoaldirect attention toward or away from available Information

Figure-Groundvisual separation of a scene into recognizable figuresandinconspicuous background (ground)

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Graphical HierarchyGroundlarger of two contrasting areas

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Graphical HierarchyGroundgrays, light browns, heavily saturated hues

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Graphical Hierarchy

Figurelong wavelength hues

coarse texture

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Graphical HierarchyGround

Figurelong wavelength hues

coarse texturestrong edge

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Maps (Types)1. Choropleth maps

2. Isopleth maps3. Proportional symbol maps4. Dot maps

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Maps (Isopleth)

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Proportionalsymbol mapshttp://www.colorado.edu/geography/courses/geog_3053_s05/Lectures/Proportional%20Symbol%20Maps.htm

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Maps (Dot density)

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Cartograms(2004 Elections by County)

http://www-personal.umich.edu/~mejn/election/

http://www-personal.umich.edu/~mejn/election/countycartlinearlarge.pnghttp://www-personal.umich.edu/~mejn/election/countymaplinearlarge.png

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Choropleth Maps

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ClassificationsProcess of placing data into groups that have asimilar characteristic or value

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ClassificationsNatural BreaksClasses are based on natural groupings inherent in the data

Looks for where there are big jumps in data

QuantilesEach class contains an equal number of featuresGood for linearly distributed data

Equal IntervalDivides the range of attribute values into equal-sizedSubranges (e.g. 0100, 101200, and 201300)

Standard DeviationCalculates mean and then maps 1-2standard deviations above / below mean

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Custom ScalesKnow your data!

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Custom ScalesEdit the classifications and layer properties

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Original Map

LegendStates

Total PopulationPOP2003

-99 - 124,013

124,014 - 447,485

447,486 - 1,129,788

1,129,789 - 2,498,3382,498,339 - 5,393,431

5,393,432 - 9,873,548

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Custom Map

Total U.S. Population, 2003

0 - 9,99 9

10,000 - 24,999

25,000 - 49,999

50,000 - 99,999

100,000 - 499,999

500,000 - 9,873,548

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Normalizing DataDivides one numeric attribute by another in order to

minimize differences in values based on the size of areas or number of features in each area

Examples:Dividing the 5 to 17 year-old population by the total population yields thepercentage of people aged 5-17Dividing a value by the area of the feature yields a value per unit area, or density

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Normalizing Data

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Normalizing Data

Percent Population 5-176.9% - 1 2.4 %

12.5% - 17.9%

18.0% - 23.4%

23.5% - 28.9%

29.0% - 34.4%

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Map Layouts

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Printed Map Layouts

Concise TitleTopic, place, time

LegendWord Legend or Key not needed

Data SourceSource and date data was obtained

l b

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U.S. Population by County

Data obtained from U.S. Census

Total U.S. Population, 2003

0 - 9,999

10,000 - 24,999

25,000 - 49,999

50,000 - 99,999100,000 - 499,999

500,000 - 9,873,548

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Map ElementsScale

Direction Indicator Photos / Images

Neat-lines

E l f b d

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Example of a bad map...