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Coordinate Systems, the frameworks used to reference geographic locations, are one of the most important, but least understood, topics for GIS users. This workshop begins with a thorough examination of the fundamentals of Coordinate Systems, including their four main components: map projection, ellipsoids, datums, and units of measure. With this background information, we will cover a variety of exercises exploring how Coordinate Systems are handled in ESRI’s ArcMap. Participants will leave the workshop with the know-how to answer familiar Coordinate System questions such as, “why doesn’t my data line up?”, “what projection should I use to do X?”, and “my data has no coordinate system defined…what should I do?”

Prerequisites	Prior GIS experience, such as our Intro to GIS workshop, is highly recommended.
Outline	Importance of Coordinate Systems Components Reference Ellipsoid (Spheroid) Geodetic Datum Map Projection Unit of Measure Projection Classes According to Projection Geometry According to Properties Preserved On-the-fly Projection in ArcMap Changing a Data Frame’s Projection Define Projection vs. (re)Project Dealing with Common Coordinate System Problems
Materials	All Workshop Materials (.zip archive)
Additional Resources	Map Projections – A Working Manual (1987), USGS Professional Paper by John P. Snyder [pdf] Datum Transformations in ArcGIS [web link]