Some Concepts That Underpin GIS - Introducing Geographic Information Systems with ArcGIS - page 59

31. Create a thumbnail of the hydrants layer: 21 On the Geography tool bar, find the Create
Thumbnail icon. (Remember: You can determine what an icon does by looking at the ToolTip
that appears when you mouse over the icon.) Click it, then click the Contents tab and observe.
Where there was before a blank rectangle, there is now an image of the layer. See Figure 1-28.
Suppose that you want only a portion of the image to be represented in the thumbnail. Go back
to the Preview tab. Use the zoom tool to focus on the six hydrants in the northeast corner.
Make a thumbnail sketch of these. Check that it worked by clicking the Contents tab. Now make
the thumbnail a third time with all the points shown.
FIGURE 1-28
A First Look at Metadata
Meta comes from Greek, where it means “after” or “beyond.” You can generally assume that it means
“about.” So “metadata” is information about data, or data about data. There are so many things to
know about geographic data sets that those experts who work with them have established standards
for describing such data sets. You will look at metadata in more detail later, using some real data sets.
The lesson from what follows is just that metadata exists, that it consists of many elements, and that
it can be presented in different formats. A warning: The ways in which metadata is handled changed
considerably between ArcGIS versions 10.0 and 10.1. To really explore metadata you should use the help
files, or perhaps better, a search engine, to make effective use of the form of metadata you choose. There
are too many options and intricacies to go into here.
32. Click Fire_Hydrants again in the Catalog Tree. Click the Description tab. (If an Upgrade Metadata
window appears click No.) Scroll down to the bottom of the Fire_Hydrants window. There you
should see the two “sections” ArcGIS Metadata and FGDC Metadata. 22 The little triangles should
be pointing down, indicating that there is hidden information below them, as in Figure 1-29. If not,
click on the text; the arrows will change direction. If you do not see both sections, first check to
make sure the options you set in Exercise 1-4 are still the same (Customize > ArcCatalog Options
and the Metadata tab). If there is still a problem check with your instructor or the manager of your
computer system or network.
Under Description you see the thumbnail of the data set that you created and textual information that the
creator of the data set provided about the general nature of the data. Some of the metadata comes about
because ArcCatalog has inspected the data set and written it into the description.
21 As mentioned earlier: When bold italic follows the check box (e.g., __30), it constitutes a general direction.
You should read what follows the bold italics to see what specific actions you are to take.
22 FGDC stands for the Federal Geographic Data Committee of the United States government. The Web site Internet
address is www.fgdc.gov. The Committee coordinates the development of the National Spatial Data Infrastructure (NSDI).