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

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

World Vegetation

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

NC Satellite Image

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

GPS receivers

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 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.” Marble and Pequet (1983)

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

20 Computer hardware Software  Data management and analysis procedures Spatial data People needed to operate the GIS Components of a 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 –1 st in the world Interested in more history? See 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 Comparing traditional cartography & GIS: Inputs 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 DLGs  DEMs DEMs  Digital orthophotoquads Digital orthophotoquads Data recorded as points, lines, areas using electronic devices

DLGs LayerFeature Type Public Land Survey System (PLSS)Township, range, and section lines Boundaries State, county, city, and other national and State lands such as forests and parks Transportation Roads and trails, railroads, pipelines and transmission lines HydrographyFlowing water, standing water, and wetlands

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

DOQs Digital rep. of aerial photographs Corrected for image distortions Stored digitally

29 Comparing traditional cartography & GIS: Storage & Retrieval 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

30 Comparing traditional cartography & GIS: Analysis & Output 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

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