USING ARCVIEW

NOTE: The materials on these pages--both in printed form and on the World Wide Web--are to be used only in association with the Virginia Tech IPM CRSP. Reproduction or use of these pages, in part or in full, for commercial purposes is strictly prohibited. Those wishing to reproduce or use these pages for non-profit, educational purposes should contact the author at LGROSSMN@VT.EDU for permission.

Step 3: Navigating in ArcView

Notice that you can hardly see the addition to the map. The theme actually appears as a very small dot near Kingston. The reason for this is that the theme "bpkprcl.shp" represents only a very small area--in this case the gardens in Bushy Park.

Next, go ahead and click on the box to the left of the theme name "Stcath_s" in the Table of Contents.

Notice that a larger area appears around the Bushy Park area.

This indicates that in GIS we can have themes at different spatial scales (area of coverage) all tied to the same spatial database. How do we get to see a closer view of the themes of "bpkprcl.shp" and "Stcath_s" on our map?

There are several tools that enable us to navigate through different spatial scales.

We need to examine several buttons in the first row of buttons at the top to illustrate how we can navigate in ArcView.

First, go to the top of the screen to the top row of buttons below the menu. There are a group of three button in the top row of buttons that look very similar. Do not do anything yet, but for your information we will want the one in the middle. This is the "Zoom to Active Theme(s)" button.

(You know if you have the correct button by placing your cursor on top of the button and then looking at the description of the button's purpose in the status bar, the rectangular area at the bottom of the ArcView window. Also, if you hold your cursor over the button, a brief description of the button's function will appear in a yellow box below the button.)

Before using it, we need to make the theme we want to inspect active. Themes must be "active" for ArcView to work with them (we will discuss this more fully later).

To make the theme Stcath_s "active" simply click once directly on the word "Stcath_s" (not on the check box to the left) and notice that a raised rectangle has appeared around the theme's name.

This indicates that the theme "Stcath_s" is active.

Now click on the "Zoom to Active Theme(s)" button.

Notice that we have zoomed in to the St. Catherine area.

How do we get back to our original map of Jamaica?

We know that our map of all of Jamaica, represented by the theme "Ja_coast", has the widest spatial range of all the themes, so we want a tool that will let us zoom back to the widest extent possible. To do so, click on the Zoom To The Extent Of All Themes button, which is just to the left of the "Zoom to Active Theme(s)" button. This button tells ArcView to zoom out to the farthest extent possible to the outer boundaries of the theme that covers the biggest area.

Note that you do not have to make the theme with the widest spatial range "active" for the "Zoom To The Extent Of All Themes" button to work.

Let us get a close-up view of the map for the theme "bpkprcl.shp." To do so, first with your cursor click once on the box to the left of the theme name "Stcath_s" so that the check mark disappears. When you do so, the theme "Stcath_s" no longer appears displayed on our map.

Go ahead on your own and produce a close-up view of the theme "bpkprcl.shp."

Now we will use other tools to navigate in ArcView. Go ahead and click on the box to the left of the theme name "Stcath_s" in the Table of Contents so that it reappears on our map.

To see any small portion of the map in a close-up view, you can zoom in on that portion of the map. Click on the zoom-in button located at the top of the screen below the menu and then hold down the left mouse button and drag your cursor to create a rectangle around the area of St. Catherine that you want to examine. Release the mouse button when you have covered the area that you want to examine. The small area that you outlined with your cursor will now expand to fill the entire map view. You can repeat the process until you see the exact area you want.

Similarly, you can zoom back out in the map by clicking on the zoom-out button at the top of the screen and then clicking your cursor in the center of the map. After you click on the map, the map will be redrawn to show a larger area. You can keep on clicking to show progressively larger areas.

These two zoom tools ( and ) will zoom in and out at 2X by holding them over the center of where you wish to zoom in and out and by making a single click with your cursor.

You can also move the map in any direction without changing the scale of the view. Click on the pan tool button located at the top of the screen below the menu and then place your cursor--which should now look like a hand--on the map. Drag the cursor in any direction and you will move the map in that direction as well and see areas previously hidden from view.

Two other buttons are important.

The Zoom to Selected button redraws the map out to the farthest extent of features that have been selected (if selected, they will appear in yellow, as will be explained in another lesson).

The Zoom to Previous Extent button allows you to zoom back to the previous view.

[Return to beginning]

[GO TO STEP 4]