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GEOG101 Chapt02 lecture
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GEOG101 Chapt02 lecture

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Transcript

  • 1. Overview
    • Maps as the Tools of Geography
    • Locating Points on a Sphere
    • Map Projections
    • Scale
    • Types of Maps
    • Geographic Information Technologies
    • Integrating Technology: Geographic Information Systems
  • 2. Maps as the Tools of Geography
    • Maps are the primary tools of spatial analysis
    • Cartography
      • The art, science and technology of making maps
  • 3. The Geographic Grid
    • Set of imaginary lines that intersect at right angles to form a system of reference for locating points on the surface of the earth
    • Key reference points
      • North and South Poles, equator, prime meridian
    • Latitude
      • Angular distance north or south of the equator
        • Measurements ranging from 0 ° (equator) to 90° (poles)
      • Lines (parallels) are parallel and run east-west
      • Distance between each degree ≈ 69 miles
      • Can be subdivided into minutes and seconds
  • 4. The Geographic Grid
    • Prime meridian
      • Starting point for east-west measurement
      • Passes through Greenwich, England
    • Longitude
      • Angular distance east or west of the prime meridian
        • Measurements ranging from 0 ° (prime meridian) to 18 0 °
      • Lines (meridians) are farthest apart at the equator and converge at the poles
      • Can be subdivided into minutes and seconds
  • 5. The Geographic Grid
    • Time depends on longitude
    • Greenwich mean time (GMT)
      • Time at the prime meridian
    • International Date Line
      • Where each new day begins
      • Generally follows the 180 th meridian
  • 6. Land Survey Systems
    • Long-lot system
      • Long, narrow rectangles of land partitioned by early French settlers
    • Metes and bounds system
      • Used physical features, along with directions and distances, to define and describe parcel boundaries
    • Township and range system
      • East-west base lines and north-south meridians
      • Township consisted of 36 mi 2
        • Further divided into 36 sections of 1 mi 2 (640 acres)
          • Subdivided into quarter-sections of 160 acres
  • 7. Map Projections
    • Earth can be represented with reasonable accuracy only on a globe
    • Globe properties
      • All meridians are equal in length
      • All meridians converge at the poles
      • Lines of latitude are parallel to the equator and to each other
      • Parallels decrease in length as one nears the poles
      • Meridians and parallels intersect at right angles
      • The scale on the surface of the globe is the same everywhere in all directions
  • 8. Map Projections
    • Map projection
      • Method of representing the curved surface of the globe on a flat map
    • All flat maps distort some or all of the four main properties of actual earth surface relationships:
      • Area
      • Shape
      • Distance
      • Direction
  • 9. Types of Map Projections
    • Equal-area (equivalent) projections
      • Areas are in correct proportion to earth reality
      • Shape is distorted
    • Conformal projections
      • Shapes of small areas are accurately portrayed
        • No projection can provide correct shapes for large areas
      • Area is distorted
  • 10. Types of Map Projections
    • Equidistant projections
      • Distances are true in all directions from one or two central points
        • Distances between all other locations are incorrect
      • A map cannot be both equidistant and equal-area
    • Azimuthal projections
      • Directions are true from one central point to all others
        • Directions from other points are not accurate
    • Robinson projection
      • Compromise between equal-area and conformal
  • 11. Scale
    • Ratio between the measurement of something on a map and the corresponding measurement on the earth
    • Represented in three ways
      • Verbal
      • Graphic
      • Representative fraction
  • 12. Scale
    • Can range from very large to very small
    • Large-scale maps
      • Ratio of map to ground distance is relatively large
      • Considerable detail
    • Small-scale maps
      • Ratio of map to ground distance is smaller
      • Less detail; generalized
  • 13. Types of Maps
    • General-purpose (reference) maps
      • Display one or more natural and/or cultural features
    • Thematic (special purpose) maps
      • Show a specific spatial distribution or category of data
        • Natural and/or cultural phenomena
  • 14. Topographic Maps and Terrain Representation
    • Topographic maps are general-purpose maps
      • Depict the shape and elevation of terrain
      • Natural and human features
    • USGS topographic map series
    • Depicting relief (variation in elevation)
      • Spot heights
      • Contour lines
        • All points along line are of equal elevation above a datum plane, usually mean sea level
        • Contour interval is the vertical spacing between contour lines
      • Shaded relief
  • 15. Thematic Maps and Data Representation
    • Qualitative maps
      • Show the distribution of a particular class of information
    • Quantitative maps
      • Show the spatial characteristics of numerical data
    • Point symbols
      • Various symbols represent features that occur at a particular point in space
      • Dot maps
        • Each dot represents a given quantity
      • Graduated symbol maps
        • Size of symbol varies according to quantities represented
  • 16. Thematic Maps and Data Representation
    • Area symbols
      • Different colors or patterns represent features found within defined areas of the earth’s surface
      • Choropleth maps
        • Data are grouped into classes, each represented by a distinctive color, shade, or pattern
      • Area cartograms
        • Areas of units are drawn proportional to the data they represent
  • 17. Thematic Maps and Data Representation
    • Line symbols
      • Various symbols represent features that have length but insignificant width
      • Isoline maps
        • Lines of constant value
      • Flow-line maps
        • Portray linear movement between places
  • 18. Map Misuse
    • Message conveyed by a map reflects the intent and, perhaps, biases of its author
    • Techniques for making misleading maps
      • Lack of a scale
      • Simple design that omits data or features
      • Colors with a strong psychological impact
      • Bold, oversized, and/or misleading symbols
      • Action symbols
      • Selective omission of data
      • Disinformation
      • Inappropriate projection
  • 19. Remote Sensing
    • Obtaining images of an area from a distance
    • Aerial photography
      • Standard photographic film
      • Infrared film
        • False-color images
    • Nonphotographic imagery
      • Thermal scanners
      • Radar
      • Lidar
      • Satellites
        • Landsat satellites
  • 20. The Global Positioning System (GPS)
    • Network of satellites orbiting the earth that continuously transmit positions and time signals
      • Maintained by the U.S. Department of Defense
    • GPS receivers
      • Record positions of multiple satellites simultaneously to determine latitude, longitude, altitude, time
    • Numerous applications, including:
      • Precision-guided weapons
      • Navigation
      • Mapping
      • Environmental assessment
  • 21. Virtual and Interactive Maps
    • Maps are widely available on the internet
    • Google Earth
      • Combines aerial photos, satellite images, and maps with street, terrain, and other data
    • Mashups
      • Digital maps merged with data from other sources
      • Interactive mapping
  • 22. Geographic Information Systems (GIS)
    • Computer-based set of procedures for assembling, storing, manipulating, analyzing, and displaying geographically referenced data
    • Geographic database
      • Digital record of geographic information
        • Maps, surveys, aerial photos, satellite images, etc.
      • Purpose of study determines data
    • Spatial analyses
    • Map generation
  • 23. Applications of GIS
    • Various fields for a variety of purposes, including:
      • Biologists and ecologists: studying environmental problems
      • Epidemiologists: studying diffusion of diseases and entomological risk factors
      • Political scientists: evaluating legislative districts
      • Sociologists: examining patterns of segregation
      • Private sector companies: site selection, analyzing sales territories, calculating optimal driving routes
      • Government: transportation planning, analyzing patterns of crime, responding to disasters