Making Maps With GIS Getting Started with GIS Chapter 7

Making Maps With GIS 7.1 The Parts of a Map 7.2 Choosing a Map Type 7.3 Designing the Map

What is a map? n “A graphic depiction of all or part of a geographic realm in which the real-world features have been replaced by symbols in their correct spatial location at a reduced scale.”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

Map function in GIS n Storage n Temporary communication n Intermediate check of data n Final report n n To be effective, must be correctly designed and constructed.

The Parts of a Map: Map Elements

The medium is the message PaperFilmMylarMonitorProjection Broadcast TV THE DISPLAY IS PART OF THE SYMBOLIZATION

Cartographic Elements n Medium n Figure n Ground n Reference information

Cartographic Elements (2) n Border n Neatline n Insets –Scale up –Scale down n Metadata e.g. index n Off-map references

Cartographic Elements (3) n Page coordinates n Ground elements n Graticule/Grid n North arrow

Cartographic Elements (4) n Figure n Point/Line/Area symbols n Text n Place Names n Title

Cartographic Elements (5) n Reference Information n Scale n Projection(s) n Sources (2) n Credits n Legend n Reliability

Mapping uncertainty

Map “impact”: Your preference? n A. Distribution of Employment by State 1996 B. USA: Employment Distribution 1996 B. USA: Employment Distribution 1996 C. U.S. Employment: 1996 Distribution n D. America at Work n E. Where the Jobs are Today

Text: Selection and Placement

Choosing Elements n Map research n Map compilation n Worksheet n Selection n Placement n Layout n Tools in GIS not ideal

ArcGIS Map Layout a. Love it, it does everything I want. e. Drives me insane, never use it.

Choosing a Map Type n Cartographers have designed hundreds of map types: methods of cartographic representation. n Not all GISs allow all types. n Most have a set of basic types n Depends heavily on the dimension of the data to be shown in the map figure.

Choosing the Wrong Type n Fairly common GIS error. n Due to lack of knowledge about cartographic options. n Can still have perfect symbolization. n Possibility of misinformation n Definite reduction in communication effectiveness.

Map Types: Point Data n Reference n Topographic n Dot n Picture Symbol n Graduated Symbol

Reference Map

Topographic Map

Dot Map

Picture Symbol Map

Graduated Symbol Map

Map Types: Line Data n Network n Flow n Isopleth n Reference

Origin of Flow Maps Harness, H. D. (1837). Atlas to Accompany the Second Report of the Railway Commissioners, Ireland. Dublin: Irish Railway Commission.

Flow Map

Map Types: Area Data n Choropleth n Area qualitative n Stepped surface n Hypsometric n Dasymetric n Reference

Area Qualitative Map

Stepped Statistical Surface

iClicker: A=Excellent E=Horrible

Map Types: Volume Data n [Isopleth, Stepped Surface, Hypsometric] n Gridded fishnet n Realistic perspective n Hill-shaded n Image map

Isoline Map Lines join points with equal value Often point to raster: interpolated Common routines are splines and IDW Kriging also useful TIN often created as intermediate

Fishnet or Gridded Perspective View Lines on X, Y axis with hidden Line elimination Also possible to use lines at 90 deg to line of sight Many variants Can use anaglyphic stereo

Realistic Perspective View

Hill-shaded Relief Map

Image Map

Anaglyphic stereo

Shuttered Stereo

Map Types: Time n Multiple views n Animation –Moving map –Fly thru –Fly by

Small multiples

Cartographic Animations

Spatialization: SOM Skupin, A. (2002) A Cartographic Approach to Visualizing Conference Abstracts. IEEE Computer Graphics and Applications. 22 (1):

Map Type and Dimensionality

Choosing Types n Check the data –Continuous –Discrete –Accuracy & Precision –Reliability n Dimension (Point, Line, Area, Volume) n Scale of Measurment (Nominal etc.) n GIS capability n May need to supplement GIS software

Data Scaling (Stevens) n Nominal (Name of a place) n Ordinal (Small, med., large town) n Interval (Arbitrary zero e.g. Sea Level) n Ratio (Absolute zero e.g. dollars, densities)

Example: Choropleth Mapping n Data should be AREA (e.g. States) n Data should not suffer from area effect. n Population? n Per capita Income? n Elevation? Temperature? n Boundaries unambiguous. n Areas non-overlapping.

Classification n Equal Interval n Natural groups n N-tiles n Equal or unequal? n Logarithmic? Linear? Discontinuous? n How many classes? n Non-overlapping, distinctive groups.

The Need for Design n To appear professional and avoid errors, GIS maps should reflect cartographic knowledge about map design. n A map has a visual grammar or structure that must be understood and used if the best map design is desired. n Cartographic convention (e.g. forests should be green).

Symbolization Errors with a GIS

Map Design n A GIS map is designed in a process called the design loop. n Good map design requires that map elements be placed in a balanced arrangement within the neat line.

The Design Loop n Create map layout as macro n Draw on screen (proof plot) n Look n Edit macro n Repeat until happy n Make final plot

Graphic Editors

Avenza: Map Publisher

ArcPress

Poster Session

Graphic Editor Software n Vector –Adobe Illustrator –CorelDraw –Freehand n Raster –Photoshop –CorelPaint –Fractal Paint

Map Design (2) n Visual balance is affected by: n the "weight" of the symbols n the visual hierarchy of the symbols and elements n the location of the elements with respect to each other and the visual center of the map.

Visual center 5% of height Landscape Portrait

Visual Layout Title Here Eye expects (1) balance and (2) allignment

Symbol “weight” Line weight Pattern ShadingHue

Color and Map Design n Color is a complex visual variable and in a GIS is specified by RGB or HSI values. n Red, Green, Blue are additive primaries. n Magenta, Cyan and Yellow are subtractive primaries. n Saturation and Intensity map better onto values than hue.

Dimensions of Color HUE SATURATION INTENSITY

Simultaneous Contrast

Color Primaries Subtractive color Additive color

Text placement Santa Barbara L a g o o n Path right PathDownPathDown

Scale and Generalization n Smaller scale means fewer features. n Smaller scale means smoother features. n Smaller scale means combining features. n Smaller scale means displacing features. n Often scales are mixed or overgeneralized.

Map Design and GIS n When a GIS map is the result of a complex analytical or modeling process, good design is essential for understanding. n 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.

iClicker: A=Excellent E=Horrible

Coming next… n How to Pick a GIS.