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Projection/Coordinate System/Datum Exercise

Projections, coordinate systems, and datums continue to be the bane of even experienced GIS professionals and students. This topic is confusing even to people who have been active in GIS for years. In my experience in a decade and a half of working with GIS, I have continued to encounter students and professionals who appear to be clueless about this extremely important topic in GIS.

Here is a short list of questions that anyone claiming to be a GIS student, instructor, or professional should be able to answer definitively:

Under typical circumstances, one should be able to

To this end, I have put together a short exercise that will help you master this skill. There are 4 data sources, each in a different projection/coordinate system/datum combination. Some of them may have a projection defined, some may not. Some of the projection definitions may be incorrect.

The data: projection_exercise_data.zip

The four data sets are:

  1. counties (a shapefile representing counties in Washington State)
  2. tiger (a feature class in a personal geodatabase representing TIGER/Line census tracts for King County, Washington State)
  3. xycoords.txt (a comma-separated ASCIII file representing nodes for PLSS sections in the western half of the Seattle 1:100,000 scale USGS digital line graph data series)
  4. wabd (an ArcInfo interchange file representing administrative boundaries for Washington State, from the 1:2,000,000 scale USGS digital line graph data series)

Your challenge: create a set of new data sources from these, where all the output data are stored in Washington State South Zone (FIPS 4602), NAD83/HARN, units feet.

You can use any GIS application at your disposal. You can use any additional data sources you can get your hands on. I suggest using the projection checker data sets I compiled several years ago: http://gis.washington.edu/phurvitz/gis_data/projection_checker/, which includes statewide data sets for Washington State in the most common projections, coordinate systems, and datums used for this area.


Phil Hurvitz, GIS Specialist

Copyright © Phil Hurvitz, 1998-2007