Introduction to cartography geography1

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Introduction to cartography geography1

  1. 1. CartographyTypes of maps, their uses and symbols
  2. 2. What is a map?• A 2-dimensional representation of a 3- dimensional object• A generalized representation of the world• No map is ever completely accurate or complete
  3. 3. General maps• Show a variety of base information• E.g. coastlines, settlements, rivers, landforms• Showing the base data is the chief function of the map
  4. 4. Thematic maps• Show a particular theme• Other irrelevant information is filtered out• Settlements, landfor ms, coastlines etc may also be show as points of reference
  5. 5. Thematic maps – choropleth maps• Use colour to show differences in values between various areas• Advantage: easy to read• Disadvantage: can be too generalized
  6. 6. Thematic maps – proportional symbol maps• Symbols are place on the map to indicate the location of specific data• The size (proportion) of the symbols represents the quantity of the data• Advantage: data is more location-specific• Symbol sizes can be missleading
  7. 7. Using symbols that add meaning
  8. 8. Using 3D 0bjects
  9. 9. Proportional symbol map using pie charts
  10. 10. Thematic maps – isopleth maps • Also known as contour maps • Lines are used to connect data of the same value • E.g elevation (height), temperature , pressure, humidity
  11. 11. Thematic maps – dot maps• Dots are used to show the specific location of phenomena• E.g settlements, shops, deaths, earthquakes
  12. 12. John Snow’s cholera map, 1854
  13. 13. Cartograms• Thematic map• Area is substituted for another value• Therefore shapes are distorted• Not a true map since scale is variable
  14. 14. Greenhouse gas emissions 2008For more cartograms: http://www.worldmapper.org/index.html
  15. 15. Topographic maps• Show a lot of detail• Show elevation (height) above sea level• Useful for town and country planners and hikers
  16. 16. Typical symbols on topographic maps• Settlements• Communications• Natural features• Cultural features
  17. 17. All maps need:• A scale• A compass, or at least an arrow showing north. (not necessary on world maps)• A key• Without these it is not a map, it is instead a diagram or a figure
  18. 18. Scale • Shows how large objects on the map are in the real world • A map scale is therefore a ratioSource: http://www.nrcan.gc.ca/earth-sciences/geography-boundary/mapping/topographic-mapping/10091
  19. 19. Scale• Problem with small and large• Small numerical scale e.g. 1:1000 = large scale map – Large scale maps show a smaller area but greater detail• Large numerical scale e.g. 1:500,000 = small scale map – Small scale maps show a larger area but less detail
  20. 20. Ways of writing scale1. As a ratio: for example 1/10,000 or 1:10,000 – Advantage: easy to read – Disadvantage: becomes inaccurate when a map is copied2. As a scale bar: for example – Advantage: easy to visualize – Remains accurate when map is copied – Disadvantage: some scale bars do not start at zero and may be misinterpreted
  21. 21. The compass• Cardinal points: North East South West• N = 00• E = 900• S = 1800• W = 2700• Convention: north normally points straight up on a map (but not always)
  22. 22. True or magnetic north? Magnetic north True north All maps use true north Which corresponds to the Earth’s axis
  23. 23. Review• Using your course-book, find 2 examples each of the following:1. A general map*2. A choropleth map*3. A proportional symbol map*4. A dot map*5. An isopleth map*Then describe the main function of each map*most of the maps in the course book are figures, since they do not have a compass, scale etc, but ignore this

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