Geography 353 Cartography and Visualization

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Geog 353 Lecture Outline: Geographic Framework
Update: 10/5/16

Making Maps book: Chapter 5: Geographic Framework



Introduction


Geographic Framework



I. Introduction to Map Projections and Map Design

Map Projection: peel and flatten the earth...like an orange peel


Map projections are an important aspect of all mapping as all maps require the transformation of the surface of the spherical earth to a flat surface

This transformation always introduces some kind of distortion


We are used to seeing the world distorted: it looks natural


The goal is to select a map projection whose distortion does not interfere with the purpose of any given map.


Projections are important to mapping and GIS:


Vital Map Projection Issues:


Cool Free Map Projection Software (Download): G.Projector



2. What are the basic characteristics of the map projection process?


But globes are not that useful for most mapping tasks...so flatten the earth:


Map projection: transformation of the spherical surface into a plane surface



3. What are the basic kinds of map projections and distortions?

Mark Monmonier in How to Lie with Maps: map projection is a "white lie"

Map projection process always results in some kind of distortion



Tissot's Indidicatrix: perfect circles of equal size on the globe; reveal patterns of distortion on projected maps.



Importance of scale and map projection


Next:



3a Three Basic Kinds (Families) of Map Projections

Based on the idea of developable surfaces: attribute of the map projection process: what kind of flattenable surface are you projecting the sphere onto?




Azimuthal Family:


Cylindrical Family:


Conic Family:



Second major aspect of map projections


3b. Map Projections and what they Preserve from the Spherical Earth

Preserving Area: Equal Area or Equivalent Projections


  • Equal area projections very important to thematic mapping as much of thematic mapping consists of mapping area data

  • Equal area projections are a good general default for all thematic maps:


    Map Projections in ArcGIS

    1) Start ArcMap


    2) Add, to your data frame a base map Countries.lyr (in ESRIDATA_2000/world folders)


    3) Add a lat/long graticule as another layer


    Remember: equal area (equivalent) is best default: so change projection


    4) Right mouse click on the data frame your layers are in, and select Properties.


    5) Check out the characteristics of the Robinson in ArcGIS's desktop help.



    While the equal area map projections are the best default



    Preserving Shape: Conformal Projections



    Preserving Distance: Equidistance Projections



    Preserving Direction: Azimuthal Projections


    Compromise Projections


    4. Choosing Appropriate Map Projections


    Projection properties:




    Map Projection Center:




    Familiarity and Aesthetics




    Suggestions for Mapping the World


    Suggestions for Mapping Continents and Large Countries

    Projections suitable for world maps are usually not suitable for mapping continents.


    ...and for the United States...


    Suggestions for Creative Solutions to the Employment of Projections

    1. Using interrupted map projections



    2. Using hemispheric map projections: the view from space


    3. Enlarging the center of the map


    4. Showing rings of activity



    In all these cases you have to understand what is being distorted


    "The map projection provides the geometrical framework for all the points, lines, and areas compiled on the final map. Projection is a key element in the overall design. It controls the locational accuracy and final appearance of the mapped area and can be used to provide a focus for the map's message." (Borden Dent)




    II. Map Scale



    III. Map Coordinates



    Conclusions

    Lab project: setting up your state map in ArcGIS/ArcMap





    E-mail: jbkrygier@owu.edu

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