USING ARCVIEW

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Step 5: Changing Legend Colors and Display

Sometimes it is necessary to change the colors and symbols in your map to improve its ability to communicate spatial information. You can change the color, symbols, and shadings used to draw a theme.

First, drag the theme "bpkprcl.shp" so that it appears below the theme "Bpkcrops.shp" in the Table of Contents

We are going to work first with the theme Bpkcrops.shp. We want to change the color used to illustrate Bpkcrops.shp on our map, a very simple task. Double-click right on the theme name Bpkcrops.shp in the Table of Contents to bring up the "Legend Editor" dialog box.

In the Legend Editor dialog box, you will see the heading "Symbol" on the left side. Below the word "Symbol" is a blue-colored rectangle; the rectangle is blue because that is the color that is now used to represent the theme Bpkcrops.shp in our map. Now double-click on the blue rectangle ; this will enable us to change the color for Bpkcrops.shp from blue to another color.

The Fill Palette window will now appear over the Legend Editor dialog box.

Note that there are six icons across the top of this small window, the first representing the Fill Palette (which is now visible). The tools associated with these six icons across the top of this palette can be used to alter the colors, symbols, and text used to represent a theme on a map.

In the Fill Palette window, you can change the patterns within polygons drawn on the map.

Notice that the black solid square in the middle of the first row of symbols is highlighted by a square around it, which indicates that we are using a solid fill pattern (in this case, solid blue) to represent our theme Bpkcrops.shp on our map.

To change the color of the fill pattern, click on the fifth icon from the left at the top of the Palette window, which looks like a paintbrush

It brings up the Color Palette window.

Here you can change the color that you use to represent our theme.

Notice that next to the word "Color:" is a drop-down list. The current choice is "Foreground" which indicates that you want to change the foreground color of a polygon, line, or point--in this case the polygon representing Bpkcrops.shp. Click on the color light blue, which will produce a black outline around the light blue color chosen in the window.

Note also that the rectangle below "Symbol" in the Legend Editor dialog box has also changed to the light blue color we have chosen.

Now click on the Apply button at the bottom right of the Legend Editor dialog box and close both the Color Palette window and the Legend Editor dialog box. Your map should look like this with the new color displayed.

What if you want to display two polygon themes of the same place at the same time, in this case both themes bpkprcl.shp and Bpkcrops.shp? Both cannot have solid fill patterns. Here is one solution.

Double-click on the theme name Bpkcrops.shp in the Table of Contents to bring up the Legend Editor dialog box again and double-click on the light blue rectangle below the word "Symbol," which brings up the Fill Palette window.

Go ahead and click once on the white square to the left of the black solid square so that it is highlighted by the square around it.

This choice removes the solid fill pattern with a clear one. Notice that the light blue color in the small rectangle in the legend editor has also disappeared and is now clear. Close the Fill Palette window, click on the Apply button on the bottom right of the legend editor dialog box and close the legend editor dialog box. Also, check the small box next to the theme name "Bpkprcl.shp" so that it is drawn beneath the theme "Bpkcrops.shp." Your map should look like this.

Although we are actually seeing both Bpkcrops.shp and bpkprcl.shp at the same time, it is difficult to discern the new clear pattern of Bpkcrops.shp above bpkprcl.shp because the lines used to demarcate the boundaries in the two themes are so similar. We want to make the lines for the boundaries in Bpkcrops.shp much thicker to see where they are in relation to the boundaries of bpkprcl.shp.

To do so, double click on the theme name Bpkcrops.shp in the Table of Contents to bring up the Legend Editor dialog box again and then double-click on the clear rectangular box below the word "Symbol" to bring up the Fill Palette window. Notice at the bottom of the Fill Palette window is the word Outline: and the number "0.1" in the drop-down list to the right. This number indicates the thickness of the lines used to draw the boundaries. We want to make the boundaries thicker to reveal their shape. Click on the down-arrow to reveal the drop-down list and select the number "2" from the list.

and then release the drop-down list. Note also that the thickness of the edge of the rectangle below the word Symbol in the Legend Editor dialog box is now thicker.

This indicates that if you apply this choice, the lines for boundaries will be just as thick as indicated around the rectangle. Click on the Apply button on the bottom right of the Legend Editor dialog box and close both the Fill Palette window and the Legend Editor dialog box. Your map should display both themes clearly now.

This method enables you to display two polygon themes of the same area at the same time.

While we can see the boundaries of both themes clearly at the same time now, a problem remains. How do we see spatial variations in values of the two themes at the same time? In such cases, we cannot use a clear pattern to represent a theme.

We will discuss illustrating spatial variations in values of themes in another lesson, but here we will perform a crucial step. Displaying a theme in a transparent pattern will enable us to see spatial variations within a theme as well as variations in the theme drawn underneath it.

Double-click on the theme name Bpkcrops.shp in the Table of Contents to bring up the "Legend Editor" dialog box and double-click on the rectangle below the word "Symbol" to bring up the "Fill Palette" window.

Then select one of the transparent hatched patterns, as I have done.

Then click on the Color Palette button to bring up the Color Palette window. Next to "Color:" it should indicate "Foreground." Select black, which is a useful color for transparent fills when examining overlapping themes, as we are doing here.

Then, next to "Color:", change from "Foreground" and select "Background" from the drop-down list. Then click on the box on the far left of the top row with the "X" in it, which is used to represent transparent patterns.

Click on the "Apply" button in the Legend Editor dialog box and close both the Color Palette window and the "Legend Editor" dialog box. Your map should look like this:

Now we can see shadings clearly in both themes. Thus, we will be able to illustrate variations in two polygon themes at the same time later, when necessary. This is particularly useful when you want to examine and compare the spatial distribution of two polygon themes, such as soil drainage and pest populations, as illustrated below.

Such visual comparisons help in interpreting relationships. Do you see any spatial similarities in the two patterns?

We are now going to use another tool to alter the display of themes--in this case the thickness of lines used to represent themes. First, change the display of Bpkcrops.shp back to a clear pattern. Then, click on the box for the theme Jarivers in the Table of Contents so that it appears in the map.

Note that the rivers now appear just as very thin lines. Let us make them thicker so that they are easier to see.

Now double-click on the name Jarivers in the Table of Contents to bring up the Legend Editor dialog box.

Notice now that under the word Symbol we no longer have a rectangle but a line instead, which represents the line used to depict the theme Jarivers on the map. We want to change both the thickness and color of the line used to represent the rivers. Double-click on the wavy line in the box below the word Symbol to bring up the Pen Palette window. Here you can change both the size and shape of lines. Note that there is a drop-down list for Size at the bottom of the window, which represents the thickness of the line. The current size is "0.1." Click on the down arrow to bring up the drop-down list and select size "2."

Note also that the thickness of the line is now wider in the box below the word Symbol in the Legend Editor dialog box.

But we also want to change the color of the line to deep blue to better represent a river. To change the color, click on the fifth icon from the left at the top of the Pen Palette window to bring up the Color Palette window.

Click on the color blue, which will produce a white outline around the blue color chosen in the window.

Note also that the color of the line in the box below the word Symbol in the Legend Editor dialog box has also changed color.

Now click on the Apply button at the bottom right of the Legend Editor dialog box and close both the Color Palette window and the Legend Editor dialog box. Your map should look like this, with the rivers more clearly displayed.

(Some notes about colors are important. First, it is best not to choose yellow because ArcView uses that color to portray items that you have selected when performing certain types of analyses, as we will discuss in another lesson. Second, changing colors is not just for the sake of art. ArcView randomly chooses colors for themes and sometimes the colors that ArcView produces for two different themes are too similar to be displayed clearly together; in such circumstances it is necessary to change the color of one of the themes.)

To demonstrate your ability to use some of the tools that we have examined, display both polygon themes "Stcath_s" and "Bpkcrops.shp" at the same time. Display "Stcath_s" with a solid fill pattern and "Bpkcrops.shp" with a transparent one, with the outline boundaries for "Bpkcrops.shp" set at "2." What is the relation between them?

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