Characteristics and Examples of Spatial Data - Introducing Geographic Information Systems with ArcGIS - page 122

Right-click the gray box at the left end of Record 0. Click Identify on the drop-down menu. The
resulting Identify window is a quick way to see all the values of a record.
What is the GPS height shown in this record? _____________.
In the same way, identify the last record in the table.
What is the GPS Height shown in this record? ________________.
Dismiss the Identify Results window.
Note the wide variation of altitudes; since the river is usually very placid and almost level, this gives you an
idea of what you can expect in the way of vertical accuracy for individual GPS fixes—even those that have
been adjusted through a process called differential correction. On the other hand, this data set was created
a long time ago—things have improved considerably, with the addition of more and better satellites, and
more advanced receivers, but GPS vertical measurements will always be worse than horizontal ones.
10. Note the icons across the top of the table. Referring to ToolTips, type the names of the these
icons in your Fast Facts File.
Done? ( ) Yes. ( ) No.
11. If any records have been selected, click the Clear Selected Features button on the Tools
toolbar. (Alternatively, you can select the Table Options drop-down button and pick Clear
Selection.) Engage the capabilities that let you obtain statistics and see a graph (the same
capabilities that you used in ArcCatalog) to determine the average elevation (to the nearest
foot). ______________ feet. Look at the graph to see where most elevation values are
clustered. Dismiss the Statistics of Boat_SP83 window. What is the difference between the
highest elevation recorded and the second highest? _________ feet (Hint: use sort). Dismiss
the attribute table for Boat_SP83.
Looking at the GPS Track in the Context of a Variety
of GIS Data
A GPS receiver gives position, not location, information. To recognize a location, you need contextual
information. You have available, on the DVD, part of which you copied to your personal folder, several
digital maps and images of a portion of the Kentucky River plus a couple of vector datasets of a few
arcs from two USGS quadrangle maps. The county to the north of the river is Fayette; that to the south is
Madison. Of the two USGS 7.5-minute quadrangles that cover the area, the westernmost is COLETOWN;
the other is FORD.
A Potpourri of Types of Geographic Data
The data exist in two folders:
[___]IGIS-Arc\River
[___]IGIS-Arc\Kentucky_wide_data