ArcView Start-up

FREC 480 -- Getting Started in ArcMap
Download and unzip the data for Project 1 to your data stick. This geodatabase file contains five minimally-processed shapefiles: US counties, lakes, rivers, highways and cities.

To start an ArcMap session, double click on the ArcMap shortcut icon. Start with a new empty map. Click the "Add Data" button (plus sign on the yellow diamond) to add the shapefiles from the geodatabase to your map.

Your layers will be displayed in arbitrary colors in the map, points on top of lines on top of polygons. The map paints each of the checked layers in bottom-to-top order. To turn the display of a layer on or off, click the check box. To hide or unhide a layer's legend, click the plus/minus box next to the check box. Left-click the icon below the layer name to change how it displays. If the Table of Contents is in "Display" mode you can rearrange the display sequence of the different layers by dragging a layer up or down in the legend box with the left mouse button.

Each of these layers includes the coordinate data used to display the individual geographic features within the layer, as well as some attribute data. For example, the Counties layer include lots of census data on population, housing, etc. By default, Arc will display all the features in a layer the same way, but you can have the features represent the values of any attribute field. An example is shown below.

But first, this map needs a projection! These shapefiles have spherical lat-lon coordinates that are treated like planar coordinates, so the map looks pretty distorted. ArcGIS can reproject your map to make it look a lot better, using any number of projections. Under View--Data Frame Properties, click the "Coordinate System" tab and navigate through "Predefined" "Projected Coordinate System" "Continental" "North America" and pick one of the North America or USA projections such as "USA Contiguous Albers Equal Area Conic." Once you select the projection and click "OK" the map will repaint in that projection.

Getting Oriented

You can pan or zoom your map any way you like with the Tools icons. (Placing the mouse over each tool identifies it.) The magnifying glass icons are interactive zoom tools: use the mouse to drag a zoom rectangle on the map. The arrow-in and arrow-out icons are fixed percent zooms. The hand icon is the interactive pan tool. The globe icon sets the map to its full extent.

The outlined arrow is an interactive feature select tool: click on individual map features or select all features within a drawn rectangle. The black arrow is for selecting map graphic elements such as titles, labels, etc.--not features. The information tool accesses the data associated with any map feature you click on. The measure tool measures incremental and total linear distances between successive points you click on the map; double-click to terminate this tool.

Zoom your map to the continental US only.

To manage the display of an individual map layer, double-click on the layer name or right-click on the name and select "Properties." The most useful Layer Properties tabs:

"Symbology" accesses all the thematic controls for the layer, allowing you to set display styles for different feature categories.
"Source" tells you the layer's native coordinate system and directory path.
"Selection" lets you specify how selected features in the layer should be displayed
"Display" lets you control the layer's degree of transparency.
"Labels" lets you format feature labels on your map.

Basic Thematic Mapping

In the Counties shapefile's Properties window and click the "Symbology" tab. The default displays all features with a single symbology. Click the symbol box to obtain a menu of color, fill and outline options, and start experimenting!

Try creating a thematic map of income inequality by county. The GINI99 field at the end of the Counties attribute table is a standard economic measure of income inequality: a higher Gini coefficient implies more inequality. In the Counties layer's Properties window, click the "Symbology" tab, pick "Quantities" and "Graduated Colors." In the "Values" pulldown menu in the Fields section, select "GINI99" Choose the number of categories you want. Then pick a nice color ramp.

Creating new feature attributes

Right-click on the Counties layer and open its attribute table. This table includes fields MALE65UP and FEMAL65UP from which you can add to obtain total "Elderly" in a new field. field. First, click the Table Options icon at the upper left of the table, and click "Add Field..." Give it a name like "Elderly" and specify a "Short Integer" field Type; then click "OK." Scroll to the far right of the table to make sure the new field was created.

Right-click on the Elderly field name, and access the Field Calculator. Enter FEMAL65UP + MALE65UP in the expression field (using the mouse avoids typos) and click "OK." Now create a thematic map of Elderly normalized by POP2000 to show percent elderly.

Classification Methods

Now you can "spin" the story your map is telling. Click the "Classify" box to access the Classification menu window. The default choice is "Natural Breaks," which is a often a useful compromise between "Equal Interval" and "Quantile." Specify the number of categories you want the counties grouped into; you can specify category ranges manually if you like. The histogram shows the distribution of counties across the range of data values. Click "OK" to close the Classification and Layer Properties windows, and you should now have a thematic map showing population densities by county.

The three maps below illustrate three different classification methods applied to identical data. In each map the counties are assigned to 10 categories, and the same green-to-red color ramp is applied. The distribution of counties appears pretty normal (in the statistical sense) with few c ounties on the tails and most counties concentrated symmetrically around the mean.

The equal-interval mapping assigns most counties to mid-range categories, and has relatively low color contrast. On the other hand, the quantile mapping assigns 10% of the counties to each category, so the categories on the tails have much larger ranges than the categories near the mean, and the map may overdramatize the "geezer crisis" in the heartland (red is a good "crisis" color!). The natural breaks classification is a compromise.

The point here is that your choices of colors and classification method really shape your map's message.

Try out some of the alternative thematic mapping techniques: graduated symbols, dot-density, etc.

Once you get an appealing thematic map created, you can Edit--Copy Map to Clipboard or File--Export it as a GIF image. To make this a proper map, you would need to add a titles, labels, north arrow, scale bar or ratio, projection information, legend, etc. You can add some these elements to your map in Data View. Others can only be added via the Layout View, which is ArcGIS's formal cartographic composition environment. You can switch between Data and Layout Views by clicking the little earth and page icons at the bottom left of your map.

Note that the Layout View is live-linked to the Data View so that when you zoom or pan the map in the Data View, the map in the Layout View will be zoomed or panned the same way.

To quickly label the features in a map layer using some attribute field, use the "Labels" options in Layer Properties. To add a data frame, text or graphics to your Map View, use the Insert menu. Anything you add in the map view will also appear in the Layout View. If you switch to the Layout View, the Insert menu also lets you add additional map elements such as title, neatline (box around the map), legend, scale bar, and north arrow or compass rose.

Rather than providing you with lots of step-by-step directions in this course, I want you to explore this software and its capabilities for yourself. Your initial progress may be a little slower, but this exploratory approach will give you a better mastery of tools and techniques that you can apply to your own projects later on.