Geografiske informasjonssystemer GIS SGO1910

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Geografiske informasjonssystemer (GIS)SGO1910
SGO4930 Vår 2004
Foreleser Karen OBrien (karen.obrien_at_cicero.uio.
no) Seminarleder Gunnar Berglund
(gunnarbe_at_student.sv.uio.no)
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Course Objectives

• To provide students with a basic understanding of
  geographic information science
• To provide students with practical experience in
  using ArcGIS software
• To apply both theory and practice to a real
  research project (Oslo project).

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Readings

• Longley, P. A., Goodchild, M. F., Maguire, D. J.,
  and D. W. Rhind. 2001. Geographic Information
  Systems and Science. Chichester John Wiley and
  Sons, 454 pp.
• Reading for Oslo Project
• Wessels, T. 2001. Losing control? Inequality
  and Social Divisions in Oslo. European Planning
  Studies, 9, 7, 889-906. Wessels, T. 2000.
  Social polarisation and socio-economic
  segregation in a welfare state the case of Oslo.
  Urban Studies, 33, 11, 1947-1967.

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Grading

• 30 Six laboratory assignments (5 points each)
• 20 Two mid-term quizzes (10 points each) (Uke 6
  Uke 10)
• 25 Final Project (25 points)
• 25 Final Exam (25 points)

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Lab Assignments

• Submitted on your own home page
• Due dates two weeks after each lab
• Criteria for evaluation will be provided with
  each lab

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GIS Labs

• ArcGIS 8.0 (GIS)
• Excel (data base files)
• Hot Metal (web pages)
• Adobe Photoshop (sizing maps and pictures)
• WinZip (decompressing files)

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Mid-term quizzes

• Each quiz worth 10 points
• Multiple choice, true-false questions based on
  readings and lectures
• 45 minutes to complete the quiz

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Project

• Identify a problem or question to address related
  to Oslo
• Collect and edit data (including new data with a
  GPS)
• Use GIS to map and analyze data
• Present results.
• Due May 3rd, 2004

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Final Exam

• 28. mai kl. 0900  (3 timer)
• Essays, short answer, multiple choice, true-false
• Based on lectures, readings, and labs

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Masters Students

• a brief review of two academic articles that use
  GIS in relation to the students field of
  interest (urban geography, development geography,
  political geography, etc.)
• a discussion of potential ways that GIS can
  contribute to their masters thesis (e.g.,
  mapping, analysis, etc.)
• identification of data sources related to their
  thesis (this can be general if no thesis topic
  has been chosen)
• an outline of the steps that need to be taken to
  use GIS in the thesis (for example, an outline of
  the steps involved in making a map of Ghana
  showing population density and road networks).

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Questions

• My office hours Tuesdays, 9.30 11.00 (Room
  321)
• (or by appointment, at CICERO)
• Lab assistance Thursdays, 9.30 11.00

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Why take this course?

• GIS is a useful tool with a wide range of
  applications
• GIS is a skill that is in demand, with a growing
  market
• Geographers have numerous advantages related to
  GIS
• GIS is challenging (but fun!)

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What is a GIS?

• A computer system capable of holding and using
  data describing places on the earths surface.
• An organized collection of computer hardware,
  software, geographic data, and personnel designed
  to efficiently capture, store, update manipulate,
  analyze, and display all forms of geographically
  referenced information.

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Geographic Information System

• Organized collection of
• Hardware
• Software
• Network
• Data
• People
• Procedures

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A GIS by any other name

• Land Information System
• Delivery Routing System
• Emergency Response System
• Disaster Planning System
• Crime Monitoring System
• Real Estate Homefinder System

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Why is GIS Important?

• Provides a consistent framework for integrating
  spatial and other kinds of information within a
  single system (ideal for interdisciplinary work).
• Permits manipulation and display of geographical
  (digital) data in new ways.
• Makes connections between activities based on
  geographic location.

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What can a GIS do?

• Location (Where is it...)
• Condition (What is it...)
• Trend (What has changed...)
• Pattern (What is the pattern...)
• Routing (Which is the best way ...)
• Modeling (What if...)

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A Brief History of GIS

• GISs origins lie in thematic cartography.
• Many planners used the method of map overlay
  using manual techniques.
• Manual map overlay as a method was first
  described comprehensively by Jacqueline Tyrwhitt
  in a 1950 planning textbook.
• HcHarg used blacked out transparent overlays for
  site selection in Design with Nature.

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Map Overlay
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A Brief History of GIS (cont.)

• The 1960s saw many new forms of geographic data
  and mapping software.
• Computer cartography developed the first basic
  GIS concepts during the late 1950s and 1960s.
• Linked software modules, rather than stand-alone
  programs, preceded GISs.
• The Harvard University ODYSSEY system was
  influential due to its topological arc-node
  (vector) data structure.

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A Brief History of GIS (cont.)

• GIS was significantly altered by (1) the PC and
  (2) the workstation.
• During the 1980s, new GIS software could better
  exploit more advanced hardware.
• User Interface developments led to GIS's vastly
  improved ease of use during the 1990s.
• During the 1990s, new GIS software could better
  exploit more advanced hardware.
• So far in the 2000s
• Internet becomes major deliver vehicle for GIS
• More than 1 million active users of GIS
• GIS is linking to other technologies (e.g. mobile
  phones, palmtops, etc.)

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Interest in GIS is Rising

• Applications via Internet
• Price reductions
• Greater awareness
• Improved ease of use
• Better technology
• Proliferation of data
• Commercial software packages
• Real applications
• Proven costbenefit cases

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Business of GIS

• GIS industry is worth over 7 billion
• Software
• Data
• Services
• Publishing
• Education

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GISystems, GIScience and GIStudies

• GISystems
• Emphasis on technology and tools
• GIScience
• Fundamental issues raised by the use of GIS and
  related technologies
• Spatial analysis
• Map projections
• Accuracy
• Scientific visualization
• GIStudies
• Systematic study of the use of geographic
  information

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Sources of Information on GIS

• The amount of information available about GIS can
  be overwhelming.
• Sources of GIS information include journals and
  magazines, books, professional societies, the
  World Wide Web, and conferences.
• GIS has Web Home pages, network conference
  groups, professional organizations, and user
  groups.
• Most colleges and universities now offer GIS
  classes in geography departments.

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GIS Resources Conferences
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GIS Konferans Oslo Plaza 4.-6. februar 2004

• Geodata og ARCen ønsker for 15. gang alle
  GIS-interesserte velkommen til tre fullspekkede
  og interessante dager! Konferansen henvender seg
  som vanlig til alle våre brukere, men også til
  deg som er ny i GIS verdenen.Programmet består
  av fire parallelle sesjoner hvor det presenteres
  et bredt spekter av tema innenfor blant annet
  innsamling, forvaltning, analyse og presentasjon
  av geografiske data. Her får du muligheten til å
  skape kontakter og få inspirasjon fra andre innen
  samme interesseområde. For den som er interessert
  i teknikk, byr vi på rundt 30 minikurs hvor du
  får opplæring av konsulenter fra Geodata.
• Pris 150 NOK ( dagsbesøk)
• Se http//www.geodata.no/custom/program2004.htm

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GIS Resources Glossies
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Major GIS-Only Journals

• International Journal of Geographical
  Information Systems
• Geographical Systems
• Transactions in GIS
• Geo Info Systems
• GIS World

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Specialty Journals

• Business Geographics
• GIS Law
• GrassClippings
• GIS Asia/Pacific
• GIS World Report/CANADA
• GIS Europe

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Regular GIS Papers

• Annals of the Association of American Geographers
• Cartographica
• Cartography and GIS
• Computer Computers, Environment, and Urban
  Systems
• Computers and Geosciences
• IEEE Transactions on Computer Graphics and
  Applications
• Photogrammetric Engineering and Remote Sensing

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Occasional GIS papers

• Cartographic Perspectives
• Cartographica
• Journal of Cartography
• Geocarto International
• IEEE Geosciences
• International Journal of Remote Sensing
• Landscape Ecology
• Remote Sensing Review
• Mapping Science and Remote Sensing
• Infoworld

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Popular Distribution Magazines

• Business Geographics
• Geo Info Systems
• GIS Law
• GIS World
• GPS World
• GEODATA

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Part II Thinking Spatially

• What is spatial data?
• How can spatial data be represented digitally?
• Rasters and vector models

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• Geographic problems usually involve location.
• GIS A special class of information systems that
  keep track of events, activities and things, but
  also where these events, activities, or things
  happen or exist.
• The difference between GIS and basic mapping and
  spreadsheet programs lies in its ability to
  handle spatial data.

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The Nature of Spatial Data

• Distributed through space
• Can be observed or described in the real world
  and identified by geographical location
• Change through space and time

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Spatial and non-spatial data
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Map of Bosnia and Heregovina
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Spatial is Special

• Geographic Earths surface and near-surface
• Spatial any space (including geographic) e.g.
  medical imaging
• Geospatial synonymous with geographic

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Sensing the World

• Personal experience limited in time and space
• One human lifetime
• A small fraction of the planets surface
• All additional knowledge comes from books, the
  media, movies, maps, images, and other
  information sources
• From indirect or remote sensing

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Representations

• Are needed to convey information
• Fit information into a standard form or model
• In the diagram the colored trajectories consist
  only of a few straight lines connecting points
• Almost always simplify the truth that is being
  represented
• There is no information in the representation
  about daily journeys to work and shop, or
  vacation trips out of town

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Representations Occur

• In the human mind, when information is acquired
  through the senses and stored in memory
• In photographs, which are two-dimensional models
  of light received by the camera
• In written text, when information is expressed in
  words
• In numbers that result from measurements

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Digital Representation

• Uses only two symbols, 0 and 1, to represent
  information (e.g., 1111 15)
• The basis of almost all modern human
  communication
• Many standards allow various types of information
  to be expressed in digital form
• MP3 for music
• JPEG for images
• ASCII for text
• GIS relies on standards for geographic data

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Why Digital?

• Economies of scale
• One type of information technology for all types
  of information
• Simplicity
• Reliability
• Systems can be designed to correct errors
• Easily copied and transmitted
• At close to the speed of light

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Accuracy of Representations

• Representations can rarely be perfect
• Details can be irrelevant, or too expensive and
  voluminous to record
• Its important to know what is missing in a
  representation
• Representations can leave us uncertain about the
  real world

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The Fundamental Problem

• Geographic information links a place, and often a
  time, with some property of that place (and time)
• The temperature at 34 N, 120 W at noon local
  time on 12/2/99 was 18 Celsius
• The potential number of properties is vast
• In GIS we term them attributes
• Attributes can be physical, social, economic,
  demographic, environmental, etc.

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The Fundamental Problem (cont.)

• The number of places and times is also vast
• Potentially infinite
• The more closely we look at the world, the more
  detail it reveals
• Potentially ad infinitum
• The geographic world is infinitely complex
• Humans have found ingenious ways of dealing with
  this problem
• Many methods are used in GIS to create
  representations or data models

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Discrete Objects and Fields

• Two ways of conceptualizing or modeling
  geographic variation
• The most fundamental distinction in geographic
  representation

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Discrete Objects

• Points, lines, and areas
• Countable
• Persistent through time, perhaps mobile
• Biological organisms
• Animals, trees
• Human-made objects
• Vehicles, houses, fire hydrants

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Fields

• Properties that vary continuously over space
• Value is a function of location
• Property can be of any attribute type, including
  direction
• Elevation as the archetype
• A single value at every point on the Earths
  surface
• The source of metaphor and language
• Any field can have slope, gradient, peaks, pits

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Examples of Fields

• Soil properties, e.g. pH, soil moisture
• Population density
• But at fine enough scale the concept breaks down
• Identity of land owner
• A single value of a nominal property at any point
• Name of county or state or nation
• Atmospheric temperature, pressure

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Rasters and Vectors

• How to represent phenomena conceived as fields or
  discrete objects?
• Raster
• Divide the world into square cells
• Register the corners to the Earth
• Represent discrete objects as collections of one
  or more cells
• Represent fields by assigning attribute values to
  cells
• More commonly used to represent fields than
  discrete objects

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A raster data model uses a grid.

• One grid cell is one unit or holds one attribute.
  
• Every cell has a value, even if it is missing.
• A cell can hold a number or an index value
  standing for an attribute.
• A cell has a resolution, given as the cell size
  in ground units.

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Generic structure for a grid
Grid extent
Grid cell
s
w
o
R
Resolution
Columns
Figure 3.1
Generic structure for a grid.
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Legend
Mixed conifer
Douglas fir
Oak savannah
Grassland
Raster representation. Each color represents a
different value of a nominal-scale field denoting
land cover class.
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Characteristics of Rasters

• Pixel size
• The size of the cell or picture element, defining
  the level of spatial detail
• All variation within pixels is lost
• Assignment scheme
• The value of a cell may be an average over the
  cell, or a total within the cell, or the
  commonest value in the cell
• It may also be the value found at the cells
  central point

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The mixed pixel problem
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Vector Data

• Used to represent points, lines, and areas
• All are represented using coordinates
• One per point
• Areas as polygons
• Straight lines between points, connecting back to
  the start
• Point locations recorded as coordinates
• Lines as polylines
• Straight lines between points

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The Vector Model

• A vector data model uses points stored by their
  real (earth) coordinates.
• Lines and areas are built from sequences of
  points in order.
• Lines have a direction to the ordering of the
  points.
• Polygons can be built from points or lines.
• Vectors can store information about topology.

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Raster vs Vector

• Volume of data
• Raster becomes more voluminous as cell size
  decreases
• Source of data
• Remote sensing, elevation data come in raster
  form
• Vector favored for administrative data
• Software
• Some GIS better suited to raster, some to vector

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Building complex features

• Simple geographic features can be used to build
  more complex ones.
• Areas are made up of lines which are made up of
  points represented by their coordinates.
• Areas Lines Points

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Areas are lines are points are coordinates
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Properties of Features

• size
• distribution
• pattern
• contiguity
• neighborhood
• shape
• scale
• orientation.

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Basic properties of geographic features