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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
• 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
• 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
• 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
• Record positions of multiple satellites simultaneously to determine latitude, longitude, altitude, time
• Numerous applications, including:
• Precision-guided weapons
• Mapping
• Environmental assessment
• 21. Virtual and Interactive Maps
• Maps are widely available on the internet
• 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