GEOG101 Chapt02 lecture
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GEOG101 Chapt02 lecture

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    GEOG101 Chapt02 lecture GEOG101 Chapt02 lecture Presentation Transcript

    • 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
    • Maps as the Tools of Geography
      • Maps are the primary tools of spatial analysis
      • Cartography
        • The art, science and technology of making maps
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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