Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition

Looking at Reference Systems

____ 8. In the Catalog Tree contract the ArcGlobeData entry. Expand Reference Systems. Here are 10 plus ways of dividing up the planet’s surface that are scientifically, if somewhat randomly, devised. Click usgs250q.shp. These are polygons that represent the United States Geological Survey 1-to-250,000-scale quadrangle maps. Zoom in on one quadrangle. Using the coordinate values shown in the lower-right corner of the window determine how many degrees it is from west to east? ____________. How many degrees from south to north? ____________. Zoom back to the full extent. Pick a quadrangle at random with the Identify tool, and look at the attributes. Why do you think there are four possible state names? _______________________________________________________________________________.

____ 9. Look at the table of usgs250q.shp. Select the QUAD_NAME column. Click Table Options > Find. Find Boston. Parts of what states would you think would appear on that quadrangle, based on the ST_NAMEn columns? __________________, ___________________, ___________________, ___________________. Select the ST_NAME1 column. How many quads are contained completely by Washington State? _________. Just for a diversion, click Globe View. Spin it around a little. Also notice that a quadrangle in the northern United States covers less land area than one in the southern United States, since the “rectangles” are defined in terms of meridians and parallels. Now bring back the Geography. ...