Geography Reference
In-Depth Information
9.
Run through the same exercises with cole_rock_polygon as you did with cole_soil_polygon,
looking at different levels of zoom:
❏
Summarize (on the NAME field) calling the resulting table Summary_NAME
❏
Identify some polygons
❏
Label polygons (use the NAME field)
❏
Display the polygons with different colors
Using the Identify tool, indicate what sort of rock the river bed is made of __________.
10.
In the Layer Properties window for cole_rock_polygon, click the Labels tab and change the size
of the labels to 10 points. Experiment with different scales by typing into the text box on the
Standard toolbar. (You only need to type the denominator of the scale fraction—the software
will understand the scale you mean.) Notice that with scales smaller than about 1:30,000 (like
1:50,000), the labels are pretty much useless. And annoying! Select the Labels tab from Layer
Properties, and then click the Scale Range button. Activate the radio button for “Don't Show
Labels When Zoomed. In the Out Beyond text box, type 30000. Click OK, Apply, and OK. Now
notice that a zoom level of 1:30000, you see labels. At 1:30001, you don't.
The concept of showing details of layers only between specified scale levels applies to feature
as well as labels. Suppose that you didn't want to see the streams when the data frame was
zoomed out beyond 1:80,000.
11.
Turn on all TIGER streams. Right-click TIGER_streams and click Properties. Under the General
tab, in the Don't Show Layer When Zoomed Out Beyond field, type 80000. Click Apply, then OK.
Using the Magnifying glass icons and/or the Fixed Zoom In and Out tool on the Tools toolbar,
zoom in and out on the data frame. Observe the scale text box for the scale and observe the
map for the presence (or absence) of streams. Also notice that when the streams aren't being
displayed, the on-off check box next to TIGER_Streams changes to checked but grayed out.
Rasters of Land Cover Data
Of considerable interest to urban and regional planners is what is called “land cover” (or the allied but
somewhat different concept of “land use”): the vegetation, water, natural surface, human activity on the
land surface, and so on. In the following, you will load a data set that describes land cover in Fayette
County Kentucky at a high-level of resolution.
12.
Load as a layer fyttelc06alii, which is a raster, you can find in [___]IGIS-Arc\Kentucky_wide_
data. If asked, do not build pyramids. Turn all other image and polygon layers off. Zoom to the
full extent of the data set to get an idea of the amount of data. Zoom to the GPS track. See
Figure 2-41. Based on the color of the cells and looking at the legend, what would you say the
code for open water is? ______. What is the code cultivated crops? _______. Verify each of
these using the Identify tool. Zoom further in so that you can measure the width of a cell. What
are the dimensions of the cells in this data set? _____________ feet. Which is __________
meters. How much area in each? ____________ square feet. An acre would contain how many
cells? ____________. As I said, this is a high-resolution data set.
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