Geografiske informasjonssystemer Geografiske informasjonssystemer (GIS)(GIS)
SGO1910 & SGO4930SGO1910 & SGO4930 Vår 2004 Vår 2004
Foreleser: Karen O’Brien ([email protected])Seminarleder: Gunnar Berglund ([email protected])
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of all or part of a geographic realm in which the real-world geographic realm in which the real-world features have been replaced by symbols in features have been replaced by symbols in their correct spatial location at a reduced their correct spatial location at a reduced scale.”scale.”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.
