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Introduction to Geographic Information

Introduction to Geographic Information. Fall 2006 Instructor: Christine Erlien. Overview. What is geography? What is geographic information? How do we get it? What do we do with it? What is a GIS? Difference from CAC, CAD, analog mapping GIS applications Tool versus science.

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Introduction to Geographic Information

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  1. Introduction to Geographic Information Fall 2006 Instructor: Christine Erlien

  2. Overview • What is geography? • What is geographic information? • How do we get it? • What do we do with it? • What is a GIS? • Difference from CAC, CAD, analog mapping • GIS applications • Tool versus science

  3. Geography = Place names only?

  4. What is geography? • The scientific study of the locational and spatial variation in physical and human phenomena • Where things are located on the earth’s surface • Why things are located where they are • How places differ from one another • How people interact with the environment

  5. Geographic Information • Examining patterns & processes of human and physical phenomena on the surface of earth • Examples of geographic information: • Spatial distribution of world population totals or growth rates • Location of Chapel Hill • Interstate I40’s spatial pattern • Urban sprawl/development of Raleigh over time

  6. http://sedac.ciesin.columbia.edu/gpw/

  7. World Vegetation http://www.miamisci.org/ecolinks/mapbiosphere.html

  8. http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_world.htmlhttp://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_world.html

  9. Geographic Information (GI) • GI - static or dynamic? • Static: Does not change position • Benchmarks • Locations, such as city/town, lake, park • Dynamic • Car with On-Star recording its position • Cell-phones used to track children’s locations • Studying population change at a particular location over time

  10. How do we obtain geographic information? Aerial photographs Digital remote sensing Surveying Censuses Global Positioning System Digitizing maps

  11. Aerial photograph from http://terraserver.microsoft.com

  12. NC Satellite Image www.geology.com

  13. Surveying: benchmarks • Geodetic control points • Mark a point of known vertical elevation • Height calculated from height of nearby benchmarks

  14. GPS receivers

  15. Digitizing

  16. We’ve collected GI, now what do we do with it? • Analyze the data • Make maps to present the data to others • How? • By using a GIS

  17. GIS: Geographic Information Systems • GIS is built on collective knowledge • Geography • Cartography • Computer science • Mathematics • Many definitions, depending on whom you ask • Demers (our textbook) cites Marble & Pequet (1983), who talk about what we do with a GIS and how we do it 

  18. Marble and Pequet (1983) Data: Both spatial and temporal Spatial: Related to the space around us Temporal: Related to time The what and how of GIS: Data input subsystem: Collecting & preprocessing data Data storage & retrieval subsystem: Retrieval, updating, editing Data manipulation & analysis subsystem: Analysis & modeling Reporting subsystem: Display What this boils down to:  “GIS is an information system that allows for capture, storage, retrieval, analysis and display of spatial data.”

  19. GIS • An information system that allows for • Capture • Storage • Retrieval • Analysis • Display

  20. Components of a GIS • Computer hardware • Software • Data management and analysis procedures • Spatial data • People needed to operate the GIS

  21. The rise of GIS • Canada, early 1960s, Dr. Roger Tomlinson • Need: inventory & map natural resources • A huge task, aided by advances in computing technology • Computers: vacuum tubes  transistors • Faster, more reliable, cheaper • Larger memories  information storage as well as calculations possible • Mainframe used had 512K of memory!!!! • IBM develops the drum scanner to scan lines on maps –1st in the world Interested in more history? See http://www.casa.ucl.ac.uk/gistimeline/ for an interactive timeline

  22. How does GIS differ from CAC and CAD? • Computer-aided cartography (CAC): • Primarily used in map-making (display) • Examples • Global Mapper • MapMaker • ArcExplorer

  23. How does GIS differ from CAC and CAD? • Computer-aided drafting (CAD) • Used by architects to produce graphic images (display) • Images not linked to descriptive files • What key capability of GIS is lacking in both CAC and CAD?

  24. Traditional Data sources Aerial photography Digital remote sensing Survey Census & statistical data Data recorded as points, lines, areas on paper or Mylar GIS Data sources Same, plus DLGs DEMs Digital orthophotoquads Data recorded as points, lines, areas using electronic devices Comparing traditional cartography & GIS: Inputs

  25. DLGs

  26. DEMs • Digital elevation models • Usually 30 m resolution • Used to determine terrain attributes (slope aspect)

  27. http://www.ngs.noaa.gov/RESEARCH/RSD/main/yakutat/yakori_full.htmlhttp://www.ngs.noaa.gov/RESEARCH/RSD/main/yakutat/yakori_full.html

  28. DOQs • Digital rep. of aerialphotographs • Corrected for image distortions • Stored digitally

  29. Traditional Storage: points, lines, areas drawn on map Retrieval: Map reading GIS Storage: Points, lines, areas stored with spatial reference data (coordinates) & pointers Tables of characteristics (attributes) associated with coordinates Retrieval: Computer tracks where data are stored Comparing traditional cartography & GIS: Storage & Retrieval

  30. Traditional Analysis: Limited to data as presented on map Output: Mapping GIS Analysis: Allows access to raw data  can change aggregation or classification, or analyse further Output: May include maps, tables, charts Comparing traditional cartography & GIS: Analysis & Output

  31. GIS Application Areas • Government • Census Bureau: population • Dept of Agriculture: soils data • Dept of Defense/CIA: monitoring • Dept of Transportation: roads data • Political redistricting • Business • Researching retail markets • Evaluating site suitability • Evaluating health care resources • Education & Research • Land use change research • Environmental monitoring • Seismological research • Population research

  32. Reasons for GIS applications • Information Management • Data input • Data editing • Updating • Data output and display • Maps • Spatial information queries • Time series of maps (tracking storms, population growth, etc.)

  33. Reasons for GIS applications (Cont.) • Spatial Analysis • Shortest Distance • Buffer analysis • Classification

  34. The Role of GIS within Geography • GIS is an effective tool that integrates human and physical geography • GIS can combine (and overlay) human and physical data • Tool v.s. science • GIS is a tool for those who use it to conduct research on other subjects • GISci: Study of the fundamental issues arising from the creation, handling, storage, and use of geographic information

  35. To wrap up • What is geographic information? • How do we get it? • What do we do with it? • What is a GIS? • Difference from CAC, CAD, analog mapping • GIS applications • Tool versus science

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