Geografiske informasjonssystemer Geografiske informasjonssystemer (GIS)(GIS)

SGO1910 & SGO4930SGO1910 & SGO4930 Vår 2004 Vår 2004

Foreleser: Karen O’Brien (karen.obrien@cicero.uio.no)Seminarleder: Gunnar Berglund (gunnarbe@student.sv.uio.no)

Making Maps With GISMaking Maps With GIS

What is a map?What is a map?

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of all or part of a geographic realm in which the real-world geographic realm in which the real-world features have been replaced by symbols in features have been replaced by symbols in their correct spatial location at a reduced their correct spatial location at a reduced scale.”scale.”

power line

Map function in GISMap function in GIS

StorageStorage Temporary communicationTemporary communication Intermediate check of dataIntermediate check of data Final reportFinal report

To be effective, To be effective, a map a map must be must be correctly designed and correctly designed and

constructed.constructed.

The Parts of a Map: Map ElementsThe 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

Text: Selection and PlacementText: Selection and Placement

Kristiansand

BM 232

US Route 66

200

L ak e

M u d

POINT LINE AREAFigure 7.2 Some cartographic label placement conventions. Points: right and above preferred with no overlap.Lines: Following the direction of the line, curved if a river. Text should read up on the left of the map anddown on the right. Areas: On a gently curved line following the shape of the figure and upright.

Bæ

rum

Osl

o

Choosing a Map TypeChoosing a Map Type

Cartographers have designed hundreds of Cartographers have designed hundreds of map types: methods of cartographic map types: methods of cartographic representation.representation.

Not all GISs allow all types.Not all GISs allow all types. Most have a set of basic typesMost have a set of basic types Depends heavily on the dimension of the Depends heavily on the dimension of the

data to be shown in the map figure.data to be shown in the map figure.

Choosing the Wrong TypeChoosing the Wrong Type

Fairly common GIS error.Fairly common GIS error. Due to lack of knowledge about Due to lack of knowledge about

cartographic options.cartographic options. Can still have perfect symbolization.Can still have perfect symbolization. Possibility of misinformationPossibility of misinformation Definite reduction in communication Definite reduction in communication

effectiveness.effectiveness.

Map TypesMap Types

Point dataPoint data Line dataLine data Area dataArea data Volume dataVolume data Time dataTime data

Choosing TypesChoosing Types

Check the dataCheck the data– ContinuousContinuous– DiscreteDiscrete– Accuracy & PrecisionAccuracy & Precision– ReliabilityReliability

Dimension (Point, Line, Area, Volume)Dimension (Point, Line, Area, Volume) Scale of MeasurScale of Measureement (Nominal, ordinal, etc.)ment (Nominal, ordinal, etc.) GIS capabilityGIS capability Is there aIs there a need to supplement GIS software need to supplement GIS software? (e.g. with a ? (e.g. with a

drawing package)drawing package)

The Need for DesignThe Need for Design

To appear professional and avoid errors, To appear professional and avoid errors, GIS maps should reflect cartographic GIS maps should reflect cartographic knowledge about map design.knowledge about map design.

A map has a visual grammar or structure A map has a visual grammar or structure that must be understood and used if the best that must be understood and used if the best map design is desired.map design is desired.

Cartographic conventionCartographic conventions should be s should be followedfollowed (e.g. forests should be green). (e.g. forests should be green).

Map DesignMap Design

Good map design requires that map Good map design requires that map elements be placed in a balanced elements be placed in a balanced arrangement within the neat line.arrangement within the neat line.

A GIS map is designed in a process called A GIS map is designed in a process called the design loop.the design loop.

The Design LoopThe Design Loop

Create map layout as macroCreate map layout as macro Draw on screen (proof plot)Draw on screen (proof plot) LookLook Edit macroEdit macro Repeat until happyRepeat until happy Make final plotMake final plot

Map DesignMap Design

Visual balance is affected by:Visual balance is affected by: the "weight" of the symbolsthe "weight" of the symbols the visual hierarchy of the symbols and the visual hierarchy of the symbols and

elementselements the location of the elements with respect to the location of the elements with respect to

each other and the visual center of the map.each other and the visual center of the map.

Visual centerVisual center

5% of height

5% of height

Landscape Portrait

Visual LayoutVisual LayoutTitle Here

Title Here

Eye expects (1) balance and (2) alignment

Symbol “weight”Symbol “weight”

Line weight Pattern Shading Hue

Text placementText placement

TrondheimTrondheim

Trondheim

Trondheim

Bogstadvann

Path right

Path Down

Map Design and GISMap Design and GIS

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

The map is what distinguishes GIS as a The map is what distinguishes GIS as a different approach to the management of different approach to the management of information, so extra care should be taken information, so extra care should be taken to improve the final maps that a GIS to improve the final maps that a GIS generates in a GIS task.generates in a GIS task.