GIS LAB 1—GETTING AROUND IN ARCGIS
This lab is to introduce you to some of the features in ArcGIS. We’ll build on this knowledge in the labs to come.
On the transfer disk you will find a folder called lab 1. Drag it into the folder you have created for yourself on the C: drive of your PC.
Open ArcCatalog and navigate to the folder into which you downloaded lab 1. Open the lab 1 folder in ArcCatalog. In it you should see 5 .shp files and a file with a small blue earth in the upper left-hand corner called California_basic.mxd. This is an ArcMap map document, the others are ESRI shapefiles. Click once on the map document and use the preview tab in the right side of the window to preview the data.
Now open Arc Map from Arc Catalog using the Launch ArcMap button on the ArcCatalog toolbar. Tell it to open a new empty map.
Note that ArcMap is divided into 2 main windows with toolbars at the top, bottom and, sometimes, in between the windows (some of the toolbars are moveable and can be docked in various places. Therefore, your view may not look exactly like the one below).
The window on the left (as you view it) will contain the Table of Contents. The table of contents lists the layers that are grouped under the data frame heading. The layers have titles and legend and are grouped under the dataframe (currently just called Layers). The right hand window is the map view that will display your data.
Go back to ArcCatalog and click ONCE on the California_basic.mxd file to select it. Now drag it and drop it into the map window of ArcMap.
You should see a map of the state of California with cities on it (your colors may not be the same as mine—of course, you’re reading a black-and-white copy of this lab so what the heck am I talking about?). What shape types (points, lines or polygons) are represented by the 3 layers (California cities, California and California_coutnies) shown in the table of contents?
Let’s look at some of the tools on the uppermost toolbar.
Under the File drop down menu you can open and close map documents, add data layers, save your maps and print your documents. Most of these functions can also be accomplished by the first 4 icons in the tool bar below the drop down menus the Add Data icon used to add layers—the black ‘plus’ sign on a bright yellow field is found farther along on the toolbar). Under the File drop down menu you can also import and export data (i.e. you can export your map as a JPEG image that can be opened by a colleague who is not GIS-enabled. JPEG’s can also be imported into powerpoint presentations).
The Edit dropdown menu lets you copy, paste and delete. The icons 5-8 (read left to right) on the toolbar will also perform these tasks.
The View menu lets you do a number of things like switch from data frame to layout view (we’ll talk more about layouts later) and display various toolbars.
The insert menu lets you insert pictures, text or a new data frame into your ArcMap view.
The Selection menu contains commands useful for querying the dataset to find features that have specific attributes or a specific location. We will use this menu more in a later lesson. Tonight you’ll just learn how to select and clear features in views and tables.
The Tools menu is an important one—it allows us to turn on ArcView extensions like Spatial and 3D analyst as well as generate graphs and reports and do geoprocessing tasks like building buffers. We will use many of these features in the weeks to come.
The Windows menu shows your dataframe in both enlarged and reduced views and the help menu is just that—help for problems you are trying to solve. It also contains information about the version of the software you are using in case you need to turn to technical support.
On the toolbar below the drop down menus you can also find a few other important tools such as Undo and Redo.
and the box that contains the scale of the view.
You can change the scale of the view by using the drop down menu or by typing in the scale you want. For example, most USGS quadrangle maps in general use are 1:24,000. Type this value into the scale box. What happens?
Don’t panic! Instead go to the toolbar containing the + and – magnifying glasses and click on the symbol that looks like the earth.
This is the Full Extent button and will show you the entire area covered by your data.
Let’s play with some of the other features for now.
Start by turning off the California layer so that you can see the California counties layer. To do this, remove the check mark (by clicking on it) in the box in from of the name of the California layer in the table of contents. Practice turning layers on and off.
Now let’s reposition the layers. Using the left mouse button, click on the California counties layer in the table of contents and drag it to the top of the table of contents. What happens?
Go ahead and put the counties layer back on the bottom of the table of contents. Unlike the previous version of ArcView (3.x), the new ArcGIS automatically positions point and line layers above polygon layers.
Notice that the California layer completely covers the counties layer but doesn’t show as much detail. Let’s delete the California layer so that the counties layer shows as the background. To do this, select the California layer in the Table of Contents using a right mouse button click and select Remove from the pop up menu.
Never fear--this will not remove the layer from your computer—you can still find it using Windows and add it to the project again if you like. It simply deletes the layer from the data frame you are working in right now.
Now, let’s add a layer. Click the Add data button:
or go to File > add data using the drop down menus and add the layer CA_faults_unproj.shp. This adds a layer containing mapped major faults in California (trust me—there are many other faults that didn’t make the map!). Your map should look like this (although the colors—or shades of gray-- may vary):
In ArcGIS, you can change the names of layers and dataframe to make them more descriptive. Right click on the name CA_faults_unproj.shp and select Properties from the pop up menu. The Layer Properties box comes up. Select the General tab and change the name to CA_faults. And hit OK.
The name of the layer changes in the table of contents. It is still the older name (CA_faults_unproj.shp) in your hard drive however. The name has only been changed for this dataframe.
The name of the dataframe (Layers) is not very descriptive. Let’s change it as well. Right click on the word Layers and select Properties from the pop up menu. In the dataframe properties dialog box, select the General tab and change the name of the dataframe to Seismic Hazards. Say OK and watch the name change in the Table of Contents.
Next, use the Zoom In and Zoom Out tools (magnifying glasses) and the fixed zoom in, fixed zoom out tools (arrows) to practice zooming in and out.
(NOTE: whenever you want to change to the general pointer tool (Select elements tool), just select the black arrow on the toolbar! Otherwise you accidentally click on the map and it will zoom in or out depending on which tool is currently selected!)
The pan tool (hand) lets you move the map back and forth and up and down in the window. You can also use the “Go back to previous extent” and “Go to next extent” buttons (big blue arrows) to take you back to previous views or to return to the current view.
Now use the full extent tool (the earth icon) to view the entire map.
Zoom in on the area around Bakersfield by selecting the Zoom In tool (magnifying glass with a + inside) and dragging a box around KernCounty.
Use the identify tool to find Bakersfield.
The Identify Results box will pop up in the window. Examine the Fields column.
Now, open the theme table for CA cities by right clicking on the California_cities theme in the table of contents and selecting Open Attribute Table. Compare the field headings in the attributes of California_cities table with the field name in the Identify Results dialog box. How are they similar to or different from each other?
Now use the identify tool to click on the fault closest to Bakersfield. What is its FID value? Why don’t the names of the faults (i.e. San Andreas) appear in the identify results box?
Use the measure tool to determine how far it is from Bakersfield to the nearest point on the fault.
First click on Bakersfield and then double click on the fault. See the length (in miles) on the lower bar of the window below the table of contents (Segment: shows the length of the last line segment—if you clicked more than once—Total: shows the total length of the line segment from start to the end where you double clicked. Note the units in which the length is measured i.e. meters, miles, decimal degrees, etc.). How far is the fault from Bakersfield?
Use the full extent tool to view the entire map.
Now use the select feature tool to select KernCounty—
see a blue outline appear around the county. You can select more than one county at a time by holding down the Shift key and clicking on the counties with the Select feature tool. Try this by selecting 3 or 4 more counties.
Now, with the counties still selected, open the attribute table for CA counties. Scroll down and notice that some of the counties are highlighted in blue. Why?
At the bottom of the counties table you see a button that says All. Near it is one that says selected. Click on Selected. Now the table shows only your selected counties.
Click the All button so all counties are shown on your table. Scroll to the right on the table until you see the field labeled POP1999. Select this field by clicking on the header cell labeled POP1999. The column of cells should turn blue.
We are going to sort the California counties to find out which has the highest 1999 population and which has the lowest. Right click on the POP1999 column header and select Sort Descending from the pop up menu.
Now the records in the table are sorted in order of population from highest to lowest. Which county has the largest population? Why are there 3 entries for this county? (Hint: select all 3 entries by holding down the Shift key and clicking on the small gray square in from of each of the three records so they all turn blue. Now look at your map to see the features that are highlighted. The table and the map are interactive. To unselect the features, you can click off the map in the ocean somewhere or, on the table, go to the Options drop down menu and choose Clear Selection)
What county has the lowest population? Where does KernCounty rank? (Hint: select KernCounty on the map and then scroll through the table looking for the blue highlighted record to make it easier to find). Save your map document and exit ArcMap.