This presentation describes the geometric tools used to display the surface of the earth on a flat piece of paper. As it turns out, all the available techniques introduce distortion (e.g., tearing, compression/expansion(changing distances), shearing (changing angles)) into parts of a map. To be responsible map makers we need to be aware of these distortions so that we can choose techniques most appropriate for the job at hand. To be adept map readers we need to know what distortions have been introduced by choices made by the mapmaker. We'll just scratch the

surface in this one session on the topic so that we have enough background to proceed. We'll return later to beef up our level of expertise.

GTK 331-337

Map Projections Delve as far as your interest will take you into Carlos A. Furuti's trully excellent website, http://www.progonos.com/furuti/MapProj/Normal/TOC/cartTOC.html Cartographical Map Projections]. This [http://www.btinternet.com/%7Ese16/js/mapproj.htm" applet] demonstrates different map projections. Tissot's Indicatrix with this applet.

In ArcGIS help, look over the entries for the following:

Projection, definition of

Projection Basics Overview

Projection Types, conic (and the others on that page)

Supplementary Materials

http://kartoweb.itc.nl/geometrics/Introduction/introduction.html Geometric Aspects of Mapping by Richard Knippers

http://geology.isu.edu/geostac/Field_Exercise/topomaps/map_proj.htm Map Projections at the Geospatial Training and Analysis Cooperative

Review http://www.geometrie.tuwien.ac.at/karto/ Gallery of Map Projections at Technical University Wien

http://topomaps.usgs.gov/drg/mercproj/index.html Transverse Mercator Projections and U.S. Geological Survey Digital Products by Larry Moore (USGS)

Great explanation of how to get from projection to rectangular coordinate system

http://demonstrations.wolfram.com/WorldMapProjections/ Mathematica also has a projection applet