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Geographic Information Systems

Geographic Information Systems

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Geographic Information Systems

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  1. Geographic InformationSystems Ted Sickley 18 February 2003 Principles of Landscape Ecology

  2. Definition(academic) • The organized activity by which people • measureaspects of geographic phenomena and processes; • representthese measurements, usually in the form of a computer database, to emphasize spatial themes, entities, and relationships; • operate upon these representations to produce more measurements and to discover new relationships by integrating disparate sources; and • transformthese representations to conform to other frameworks of entities and relationships. • These activities reflect the larger context (institutions and cultures) in which these people carry out their work. In turn, the GIS may influence these structures. GIS course notes, University of Washington

  3. Definition(on-line computer dictionary) (GIS).A computer system that has maps and geographic information, and sometimes analyses of geographic data. Geographic information systems have many uses including government, tourist information, education, environmental information, engineering, marketing. From “High-Tech Dictionary” at

  4. Definition(GIS software vendor) A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on earth. ESRI GIS stands for Geographic Information Systems. A Geographic Information System is a combination of elements designed to store, retrieve, manipulate, and display geographic data - information about places. It is a package consisting of four basic parts: hardware, software, data and a thinking operator. ESRI Canada

  5. SPATIAL DATA IN ANALYZE/ PROCESS DATA OR GRAPHICS OUT Scanner Network Screen Digitizing Table Computer CD CD Spatial Database Printer FTP

  6. Vegetation Distribution Climate y x1 x2 x3 Probability of Model Soils = f(c, s, t) Topography SPATIAL DATA IN ANALYZE/ PROCESS DATA OR GRAPHICS OUT

  7. In practice HardwareSoftwareDatathe Thinking Operator

  8. Hardware Computer Global positioning system (GPS) Input scanner digitizing table PDA, data logger Output printer or plotter export data or digital image Network connection SoftwareDatathe Thinking Operator

  9. Hardware Software GIS software image processing analysis packages spreadsheets relational databases statistical (SAS, S-Plus, Oracle have GIS and spatial statistics modules) Datathe Thinking Operator

  10. HardwareSoftware Data spatially referenced information land cover, elevation, population density, utility networks, rare species locations the Thinking Operator Images from

  11. On a more conceptual level Data model how the world is represented digitally Cartographic and analytical tools display spatial data manipulate, analyze data

  12. Data model – how the world is represented digitally Geographic features streams census blocks bird nesting sites, etc. Database containing attribute information width, order, invertibrate fauna, flow age, income, number of bathrooms species, success, habitat Cartographic and analytical tools

  13. Spatial Data Components Spatial Data Geographic Component Attribute Component Qualitative Quantitative Vector: point, line, polygon topology Raster: pixel Ordinal Interval Ratio Categorical

  14. Vector vs. Raster Advantages of vector: • Good representation of entity data models • Space efficient storage of data • Topology can be described explicitly and be easily manipulated • Efficient query operation Advantages of raster: • Simple data structure • Efficient representation of highly variable data • Mathematical modeling easier because all entities have simple, regular shape

  15. Data sources Project generated Historic maps/documents Government agencies Dane County MN Data Deli USGS Private vendors Internet Geography Network Spatial data clearinghouses

  16. Data model – how the world is represented digitally Cartographic and analytical tools Mapping Visualization Spatial overlay Spatial modeling Pattern analysis Interpolation Statistical analysis Network analysis Data management Images from


  18. y = 0 y = 30 y = 50

  19. Issues, concerns Generalization, simplification Scale Accuracy, precision Error Metadata

  20. Users Landscape ecology research labs Land management agencies USFS, NPS, DNR, TNC forest products, petroleum companies Governmental agencies: all levels land records, facilities/utilities management, environmental regulation Business demographic analysis marketing site selection the press

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  24. Hall, M.H.P. and D.B. Fagre. 2003. Modeling climate-induced glacier change in Glacier National Park, 1850-2100. BioScience 53, 131-140 1850-1993, 73% reduction in glacial cover in Glacier NP Important as evidence of changing climate Digitized terminal moraine positions 1850-1979 Related glacial extents to physiographic factors and climatic drivers

  25. Hall, M.H.P. and D.B. Fagre. 2003. Modeling climate-induced glacier change in Glacier National Park, 1850-2100. BioScience 53, 131-140 Assigned a probability of melt factor to each cell in their study area Modeled glacial distribution into the future under 2 warming scenarios Also ran companion vegetation distribution model to assess reaction of vegetation to changes in soil moisture and increasing temperature