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GUS: 0262 Fundamentals of GIS

GUS: 0262 Fundamentals of GIS. Lecture Presentation 2: Cartography in a Nutshell Jeremy Mennis Department of Geography and Urban Studies Temple University. Maps as Models. Maps are models of reality .

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GUS: 0262 Fundamentals of GIS

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  1. GUS: 0262Fundamentals of GIS Lecture Presentation 2: Cartography in a Nutshell Jeremy Mennis Department of Geography and Urban Studies Temple University

  2. Maps as Models • Maps are models of reality. • They emphasize some aspects of reality in a cartographic representation while ignoring or greatly simplifying other aspects of reality.

  3. Scale the amount of reduction in the representation of a real world geographic phenomenon on a map. or, the ratio of map distance to earth distance 1:24,000 1 inch = 2000 ft verbal scale representative fraction bar scale 1 2000 ft

  4. Geometric Representation Points Lines Polygons

  5. Generalization

  6. Generalization

  7. Measurement Levels Nominal: equivalence eg. land cover (residential, industrial) Ordinal: ranking e.g. city size (small, large) Interval: ratio assuming an arbitrary 0 value e.g. temperature in degrees F Ratio: ratio assuming a true 0 value e.g. temperature in degrees K

  8. Map Projections • a means to depict the spherical earth on a two dimensional medium • cannot simultaneously preserve all of these properties of the earth in two dimensions: • shape (of a region) • distance (between two points) • direction (bearing from one point to another) • area (of a region)

  9. Map Projections

  10. Map Projections • Conformal projection • preserves direction • e.g. Mercator • Equal area projection • preserves area • e.g. Alber’s equal area

  11. Geoid and Datum Geoid: a model of the earth’s shape Clarke 1866 GRS80 Datum: reference point for establishing horizontal control NAD27 uses Clarke 1866 NAD83 uses GRS80

  12. Coordinate Systems • provide a spatial referencing system to locate points on the earth surface • spherical coordinate system • coordinates that describe locations on a sphere • planar coordinate system • coordinates that describe locations within a two dimensional Cartesian space

  13. Spherical Coordinate Systems • latitude and longitude • parallel: lines parallel to equator • meridian: lines going from pole to pole

  14. Planar Coordinate Systems • rectangular grid with X and Y axes • X: easting • Y: northing • point is defined by X,Y coordinate

  15. Planar Coordinate Systems • Universal Transverse Mercator (UTM) • units in meters • transverse cylindrical projection • 60 vertical zones cover globe • northing in meters from equator • easting in meters from false origin 500,000 meters west of zone central meridian

  16. Planar Coordinate Systems Universal Transverse Mercator (UTM)

  17. Planar Coordinate Systems • United States State Plane Coordinate System • units in feet • projection in transverse Mercator or Lambert’s conformal conic • tied to U.S. datum • one or more zones for each state with a false origin southwest of the zone

  18. Planar Coordinate Systems United States State Plane Coordinate System

  19. Types of Maps Reference Map Thematic Map Qualitative Quantitative Dot Map Isarithmic Map Cartogram Proportional Symbol Choropleth Map

  20. Dot Mapping

  21. Isarithmic Mapping

  22. Cartogram

  23. Choropleth Mapping

  24. Choropleth Mapping

  25. Choropleth Mapping Breast Cancer Incidence by County in North Carolina

  26. Classification in Choropleth Mapping Constant Intervals Equal Interval Standard Deviation Variable Intervals Quantile Arithmetic Progression Geometric Progression Natural Breaks Visual Maximum change in slope Optimal (Jenks)

  27. Classification in Choropleth Mapping

  28. Thematic Map Elements Title Legend Scale Credits Mapped and unmapped areas Borders and neatline Map symbols Place names and labeling

  29. Thematic Map Elements For more on choropleth mapping: http://www.personal.psu.edu/faculty/c/a/cab38/GEOG321/05_choro02/choro1_02.html

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