Spring Term 2006
In this assignment you will examine the effect of different projections on a simple spatial object, the circle. You will also increase your understanding of using the ArcCatalog and Editor to create data.
Open Arc Catalog
In the directory that you have chosen to do do this exercise create a new shapefile of type polygon. Define the coordinate system to be WGS84. Add a field called area and one called perimeter, make them Type Double.
In ArcMap add this newly created layer. Also, for context, add some counties so you can tell where you are.
Turn on the Editor, and choose Start Editing. Be sure that the Target is set to your shapefile.
Create a circle using the New Feature tool, use Advanced Editting to get to the Circle Tool.
Stop editing.
Use the field calculator to calculate the area and perimeter.
Use Toolbox->Data Management->Projects and Transformations->Features->Project to project your data to a variety of coordinate systems, including:
In each case append a code to the filename that will help you keep track of what coordinate system it is in. Also make sure that you keep track of what HORIZONTAL UNITS each coordinate system uses, feet or meters.
Compare the area and perimeter values that you get between NAD 1983 StatePlane Oregon North FIPS 3601 Feet Intl and NAD 1983 Oregon Statewide Lambert Feet Intl
Similarly compare all of the values from the metric coordinate systems.
Make a table comparing your results. You can find a formula for converting m^2 to feet^2 and then compare all values...
Look at the results, think about them, and discuss your confidence in measurements.