Geografiske informasjonssystemer (GIS) SGO1910 & SGO4930 Vår 2004 Foreleser: Karen O’Brien Seminarleder: Gunnar Berglund

Making Maps With GIS

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 n “A graphic depiction of all or part of a geographic realm in which the real-world features have been replaced by symbols in their correct spatial location at a reduced scale.”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

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

The Parts of a Map: Map Elements The United States of America Alaska Lambert Conformal Conic Projection Source: U.S. Dept. of State hundreds of kilometers Washington,D.C. National Capital Legend Scale Credits North Arrow Place nameInset Ground Figure Neat line BorderTitle Hawaii

Text: Selection and Placement Kristiansand BM 232 U S R o u t e L a k e M u d POINTLINEAREA Figure 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 and down on the right. Areas: On a gently curved line following the shape of the figure and upright. Bærum Oslo

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 n Point data n Line data n Area data n Volume data n Time data

Choosing Types n Check the data –Continuous –Discrete –Accuracy & Precision –Reliability n Dimension (Point, Line, Area, Volume) n Scale of Measurement (Nominal, ordinal, etc.) n GIS capability n Is there a need to supplement GIS software? (e.g. with a drawing package)

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 conventions should be followed (e.g. forests should be green).

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

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

Map Design n 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.

Visual center 5% of height Landscape Portrait

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

Symbol “weight” Line weight Pattern ShadingHue

Text placement Trondheim Bogstadvann Path right PathDownPathDown

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.