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EMR21 Lab 3

This lab session focuses on essential GIS skills, including downloading GIS data from the web and manipulating this data in ArcGIS. Participants will export their maps to AI format for further design in Adobe Illustrator. The session covers map projections, explaining how to represent a 3D sphere on a 2D plane, and the inherent distortions of distance, direction, shape, and area. Students will learn to choose the appropriate map projection based on specific needs, with practical examples from cylindrical to conic projections.

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EMR21 Lab 3

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Presentation Transcript

  1. EMR21 Lab 3 October 2 - 4 Objectives: • Download GIS data from the web • Manipulate the data in ArcGIS, export to AI format • Design in Adobe Illustrator

  2. End of lecture 1 Map projections: Taking a 3d object and modeling it in 2 dimensions

  3. A common analogy: peeling an orange

  4. Map projections – representing a 3d sphere on a 2d plane.Map projections distort at least one of these: distance, direction, shape, or area.Every projection has its own set of advantages and disadvantages.The mapmaker must select the one best suited to the needs, reducing distortion of the most important features for the area of interest.

  5. Map projection – representing a sphere on a 2d plane.A light source projected through a sphere.

  6. Cylindrical projection – projected onto a cylinder tangent to the globe. E.g. the Mercator projection created by Gerardus Mercator in the 1500s.

  7. Map projection: Cylindrical • Distances along the Equatorare true • Moving poleward, shape is significantly distorted.

  8. Conic projection – projected onto a cone which passes through the globe.

  9. Albers Equal Area Conic projection – All areas on the map are proportional to how they are on the globe. Map projections are designed to minimize distortion for specific areas on Earth. The conic projection shown here minimizes distortion for the lower 48 US states.

  10. Cubic projection

  11. Fuller projection (polyhedron)

  12. Human Migration • Thousands of years • before present

  13. Winkle-triple projectiona good choice for global maps

  14. Most GIS software allows one to changes the map’s projection to best suit the needs of the map to be made.

  15. Let’s do the lab…. Download the Lab3_US_Map.docx on the class website, Lab3 page.

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