Cartography – plotting the world


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Cartography Fundamentals, GIS and Mapping, How to create good maps, training module

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Cartography – plotting the world

  1. 1. Cartography – Plotting the world The foremost cartographers of the land have prepared this for you; it’s a map of the area that you’ll be traversing Dr. Nishant Sinha
  2. 2. Spatial is Special “Everything is related to everything else, but near things are more related than distant things” Tobler, W. 1970. A computer movie simulating urban growth in the Detroit region. Economic Geography 46, 234–40. Sometimes called the First Law of Geography (because it is generally true!).
  3. 3. Capturing Details
  4. 4. The creativity to potray
  5. 5. Cartography – amalgam of art, science and technology ▪ The art, science and technology of making maps ▪ Help to produce and analyze maps to enable communication of ideas ▪ Basic principles of map making – Has a clear motive or goal – Is directed toward an audience – Uses appropriate design elements to clearly convey its message
  6. 6. Cartography dynamics – An example ▪ Phone call Cartography
  7. 7. Cartography – a communication bridge The geographic environment Compile Recognize Select Classify Simplify Symbolize Read Analyze Interpret Imagine Map user MapMap CartographerReality Reality?
  8. 8. Cartographic elements ▪ Maps show how different features are related ▪ All maps, however, share the same common elements – Title – Legend – Scale – Directional Indicator – Inset Maps – Projection System Beauty is NOT the MAIN objective
  9. 9. The Elements of a Map: Title ▪ Most important element of the map for acquiring information efficiently is the title ▪ Identifies the map area and the type of map ▪ Cartographers may list the title simply or artistically ▪ Typically appear at the top of the map, but not always Map of Indiana Showing Its History, Points of Interest,1967, GRMC, Ball State University Libraries
  10. 10. The Elements of a Map: Legend ▪ Another important feature on a map is the legend or map key ▪ Contains information needed to read a map ▪ Most maps use symbols or colors to represent different geographic features, the meaning of which is determined by legend This legend simply identifies the roads ofTexas, but the cartographer chose to be creative in the design of the legend to add character to the map. (Texas Guide Map, 194-, GRMC, Ball State University Libraries).
  11. 11. The Elements of a Map: Scale ▪ Almost all maps have scales ▪ Scales compare a distance measured on the map to the actual distance on the surface of the earth. ▪ Scales appear on maps in several forms, but most cartographers draw a line scale as a point of reference This scale from a historical map of Kentucky features an image of GeorgeWashington surveying the land. (Kentucky:The Dark and Bloody Ground, An Historical and Geographical Map of the State of Kentucky, 1933, GRMC, Ball State University Libraries).
  12. 12. The Elements of a Map: Directional Indicator ▪ A directional indicator on a map helps determine the orientation of the map. ▪ Some cartographers place an arrow that points to the North Pole on the map.This is a “north arrow.” ▪ Other maps indicate direction by using a “compass rose,” with arrows pointing to all four cardinal directions Ancient cartographers drew elaborate, artistic directional indicators—most commonly a compass rose. (Floridae Americae Provinciae: Recens & Exactissima Descriptio, 1564, engraved reproduction, GRMC, Ball State University Libraries).
  13. 13. The Elements of a Map: Inset Map ▪ Some maps feature inset maps - smaller maps on the same sheet of paper. ▪ Provide additional information not shown on the larger map ▪ Drawn at a larger, more readable scale ▪ Usually feature areas of interest related to the larger map The larger map above is a modern map of the NileValley.The inset map shows the ancient Egyptian Empire in the same area.(National GeographicThe NileValley: Land of the Pharaohs, 1963, GRMC, Ball State University Libraries).
  14. 14. ▪ Earth is round and maps are flat, getting information from a curved surface to a flat one involves a mathematical formula called a map projection , or simply a projection ▪ This process of flattening the earth will cause distortions in one or more of the following spatial properties and No projection can preserve all these properties: – Distance – Area – Shape – Direction ▪ Type of projections based on different types of distortion – EQUIVALENCY Correct representation of area – CONFORMALITY Correct representation of shapes – EQUIDISTANCY Correct representation of distance – AZIMUTHALCY Correct representation of direction ▪ Type of projections according to the projection surface – CONIC – CYLINDRICAL – PLANAR In simple terms where the ‘paper touches the Earth’ there are no distortions. But the further the ‘paper’ is away from the surface of the Earth the greater distortions. The mathematics in different projections attempt to overcome this problem – but none remove all distortions. The Elements of a Map: Map Projections
  15. 15. G e oid E ll ips oi d S p he re S e a Le v el H e igh t F igur e 2.4 E le vat ions def ine d w ith r ef er e nce to a sphe re , el lipsoid, ge oid, or loca l se a le vel w il l al l be dif fe re nt. Eve n l oca tion a s l ati tude and longitude w ill var y som ew ha t. W hen linking fie ld da ta suc h as G PS w ith a GI S, t he use r m ust know w hat ba se to use . T errai n Earth Models and Datums
  16. 16. Standard parallels
  17. 17. Geographic Coordinates Parallels Equator PrimeMeridian PrimeMeridian Meridians
  18. 18. Type of projections according to the projection surface Standard parallel Central Meridian Polar Equatorial Oblique
  19. 19. No flat map can be both equivalent and conformal.
  20. 20. The Datum ▪ An ellipsoid gives the base elevation for mapping, called a datum. ▪ Examples are NAD27 and NAD83 Everest ▪ The geoid is a figure that adjusts the best ellipsoid and the variation of gravity locally. ▪ It is the most accurate, and is used more in geodesy than GIS and cartography.
  21. 21. Geographic Coordinates as Data
  22. 22. Equivalency ▪ Also known as Equal area Projection, that preserves the area of displayed features ▪ Shape, distance and angles are distorted ▪ The meridians and parallels may not intersect at right angles but they are marked in such a way that the area represented in each quadrangle is same with the adjacent one ▪ Shapes of the features are generally distorted for a larger area ▪ in smaller areas it is difficult to visualize unless it is measured Example: Albers Equal-Area Conic projection
  23. 23. Conformality ▪ Also known as Conformal Projection, which preserves the local shape ▪ To preserve the individual angles describing the spatial relationship this projection must show the perpendicular graticules intersecting at right angles ▪ Issue - Shapes of the larger areas cannot be preserved ▪ Used for smaller regions i.e. for large- scale maps ▪ Useful for navigational charts and weather maps Example: Mercator projections
  24. 24. Equidistancy ▪ Also known as Equidistant Projection, which preserves the distance between two points ▪ Scale is not maintained correctly throughout an entire map ▪ There are one or two lines on a map along which the scale is maintained correctly irrespective of the fact that whether they are great or small circles and straight or curved Example:
  25. 25. Azimuthalcy ▪ Also known as True direction Projection ▪ Preserves or maintains some of the great circle arcs, giving the directions or azimuths of all points on the map correctly with respect to the center Example: Azimuthal Equidistant projections
  26. 26. Conic Projections ▪ Based on the concept of the ‘piece of paper’ being rolled into a cone shape and touching the Earth on a circular line – Tip of the cone is positioned over a Pole – Line of latitude where the cone touches the Earth is called a Standard Parallel ▪ Used for regional/national maps of mid- latitude areas – such as Australia and the UnitedStates of America. ▪ Characteristics – Fan shaped when used to map large areas – Have distortions increasing away from the central circular line (the ’touch point of the paper‘) – Have very small distortions along the central circular line (the ’touch point of the paper‘) – Shapes are shown correctly, but size is distorted – Usually have lines of longitude fanning out from each other and have lines of latitude as equally spaced open concentric circlesThis is a typical example of a world map based on the Conic Projection technique. This map is centred on central Australia and the Standard Parallel is 25° South. Note how the shapes of land masses near the Standard Parallel are fairly close to the true shape when viewed from space – see the images at the beginning of this section. This includes Australia, South America and the ’tip‘ of Africa. Also note how land masses furthest away from the Standard Parallel are very distorted when compared to the views from space. Particularly note how massively large northern Canada and the Arctic icecaps look.
  27. 27. Cylindrical Projections ▪ Based on the concept of the ‘piece of paper’ being rolled into a cylinder and touching the Earth on a circular line – Cylinder is usually positioned over the Equator, but this is not essential ▪ Usually used for world maps or regional/national maps of Equatorial areas – such as Papua New Guinea ▪ Characteristics – Rectangular or oval shaped – but this projection technique is very variable in its shape – Have lines of longitude and latitude at right-angles to each other – Have distortions increasing away from the central circular line (the ‘touch point of the paper’) – Have very small distortions along the central circular line (the ‘touch point of the paper’) – Show shapes correctly, but size is distorted.. his is an example of a cylindrical map projection and it is one of the most famous projections ever developed. It was created by a Flemish cartographer and geographer – Geradus Mercator in 1569. It is famous because it was used for centuries for marine navigation. The sole reason for this is that any line drawn on the map was a true direction. However, shapes and distances were distorted. Notice the huge distortions in the Arctic and Antarctic regions, but the reasonable representation of landmasses out to about 50° north and south.
  28. 28. Planar Projections ▪ Based on the ‘flat piece of paper’ touching the Earth at a point. The point is usually a Pole, but this is not essential – Cylinder is usually positioned over the Equator, but this is not essential ▪ Also known as Azimuthal or Zenithal Projection ▪ Characteristics – Have distortions increasing away from the central point – Have very small distortions near the centre point (the ’touch point of the paper‘) – Compass direction is only correct from the centre point to another feature – not between other features – Not usually used near the Equator, because other projections better represent the features in this area When the centre of the map is the North or South Pole maps produced using Azimuthal Projections techniques have lines of longitude fanning out from the centre and lines of latitude as concentric circles. These projections are often called polar projections.
  29. 29. What are my cartographic objectives? Why?Map objectives Convey information Illustrate analysis results Highlight spatial relationships Easier comprehension of complex events How? Design objectives Fulfill map objectives Assign meaningful symbology Ensure truthful depiction of reality Fulfill communication objectives
  30. 30. What are my communication objectives? PopulationSoils Focused information Importance can vary Symbols can dominate Variety of information Equal importance Subtle symbology General map Thematic map Qualitative Quantitative
  31. 31. ▪ More than 3000 ▪ No perfect projection ▪ All have distortions Cylindrical Conical Azimuthal Direction Distance Shape Area What projection should I chose?
  32. 32. Displace? Aggregate?Omit? Simplify? Collapse? Typify? Exaggerate?Classify?Refine? C E B C2 C3 E1 B1 E5C5 B4 How much detail should I include?
  33. 33. Color Shape Texture/Pattern Gray tone value Size Qualitative Quantitative What symbols should I use?
  34. 34. What colors should I use? ▪ Connotations ▪ Conventions ▪ Preferences ▪ For screen or paper R G B Y 100 70 40 10% 20 30 50 85% Hue Value Saturation Dimensions
  35. 35. 12 colors Maximum 7- 8 shades What are the eye limitations?
  36. 36. What about the color impaired? ▪ Avoid pure green / red ▪ Vary shapes, textures ▪ Use brightness contrast (not more colors) Normal eye Red defective Green defective Blue defective
  37. 37. How do I represent names on my map? ▪ Legibility issues – Text color vs background color – Uppercase vs lowercase – No fancy fonts River RIVER River Form Tigris Orlando Color Baghdad Basra Style Qualitative San Diego Redlands Size Redlands San Diego Value Tigris Orlando Color River RIVER River Form Quantitative
  38. 38. • Readability issues Makramville Jackville1 2 How do I label names? How do I place names at POINTS? • Ambiguity issues How do I place names at LINES? • Faster reading issues How do I label contours?
  39. 39. 0 3 ft Are these dog houses? Must be visually easy to read Correct? Easy to use? ? What about my scale?
  40. 40. Objective Map form Quantity of information Easy / Complex Quality Authenticity Symbol size, color Reality Audience Conditions of use Technical limits Scale Generalization What factors control my design?
  41. 41. ALWAYS THINK of the? ? ? USER
  42. 42. Some of the world’s Best Maps Map of ‘Pangea’ with Current International Borders Map by via Reddit Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras, forming about 300 million years ago. It began to break apart around 200 million years ago. The single global ocean which surrounded Pangaea is accordingly named Panthalassa.
  43. 43. Some of the world’s Best Maps 31. Earth’s Population by Latitude and Longitude Photograph by mrgeng on Reddit Where 2% of Australia’s Population Lives Map by e8odie on Reddit
  44. 44. Some of the world’s Best Maps Reversed Map with Southern Hemisphere at Top of Map (because position of North is arbitrary) Map via
  45. 45. Some of the world’s Best Maps World Map Tattoo with Countries Visited Coloured Countries That Do Not Use the Metric System Map via Wikimedia Commons
  46. 46. Some of the world’s Best Maps The Only 22 Countries in the World Britain Has Not Invaded (not shown: Sao Tome and Principe) Map by Stuart Laycock (via The Telegraph)
  47. 47. Some of the world’s Best Maps Where Google Street View is Available Map by Google
  48. 48. Some of the world’s Best Maps Global Internet Usage Based on Time of Day Map by Carna Botnet via Reddit
  49. 49. Some of the world’s Best Maps Visualizing Global Population Density Map by valeriepieris on Reddit
  50. 50. Shown you tools to use- Thanks a ton!
  51. 51. Acknowledgement These slides are aggregations for better understanding of GIS. I acknowledge the contribution of all the authors and photographers from where I tried to accumulate the info and used for better presentation.
  52. 52. Author’s Coordinates: Dr. Nishant Sinha Pitney Bowes Software, India