data visualization - texas a&m university · 2014. 9. 22. · data visualization . francisco...

Texas A&M University 1 Department of Civil Engineering

Data Visualization

Francisco Olivera, Ph.D., P.E. Srikanth Koka Lauren Walker

Aishwarya Vijaykumar Keri Clary

Department of Civil Engineering Texas A&M University

April 21, 2014

Contents Brief Overview of ArcMap ............................................................................................................... 1

Goals of the Exercise ....................................................................................................................... 2

Computer and Data Requirements ................................................................................................. 2

Procedure ........................................................................................................................................ 2

1. Displaying and Navigating Maps ......................................................................................... 2

2. Feature Attributes and Statistics ....................................................................................... 10

3. Symbolizing Features ......................................................................................................... 16

4. Classifying Features ........................................................................................................... 23

5. Making Maps for Presentations ........................................................................................ 25

Brief Overview of ArcMap ArcMap is an application for displaying and analyzing GIS data. Data Frames are ArcMap document objects where the geographic information of the digital spatial datasets in displayed in the form of layers. A Layer is a digital spatial dataset that has been added to a data frame and has specific properties. Tables are arrays of data organized in rows and columns (i.e. fields). Tables can be stand-alone arrays of data with no geographic information included or components of digital spatial datasets in which each row includes a feature shape and a unique identification number for each feature called ObjectID.

Texas A&M University Department of Civil Engineering 2

Goals of the Exercise This exercise introduces you to the following topics:

• Displaying and navigating maps • Viewing feature attributes • Creating graphs • Changing default symbology • Symbolizing features by categorical attributes • Classifying features by standard methods • Creating layouts

Computer and Data Requirements This exercise was completed using ArcGIS 10.2. The only component of ArcGIS used was ArcView. The data used in this exercise is available on the class webpage.

Procedure

1. Displaying and Navigating Maps

(1) Open ArcMap. (2) Click File/Open. (3) Navigate to the folder the data for this exercise is saved, and open ex03a.mxd.


(4) You can see that the ArcMap document contains three layers – Flight Path, Countries, and Cities. A check mark is not inserted in the checkbox beside the name of the Cities layer in the TOC making it invisible.

(5) Make the Countries layer disappear by clicking on the check box and turning it off.


(6) Now turn it back on by clicking in the check box again. Also, turn on the Cities layer by inserting a check in the box located beside its name. The Cities layer is behind the others, out of view. To make it visible, drag the Cities layer to the top of the TOC windowpane.


(7) Open the Cities layer properties by right clicking on the Cities layer and then on Properties; the Layer Properties window appears. Select the General tab of it is not already chosen.

(8) Rename the layer by changing the name from “Cities” to “Cities Viewed” in the Layer

Name: field and then click OK to close the window.


(9) You will now learn how to use the Tools toolbar. If the toolbar is not already available, open it by going to the View dropdown menu and selecting Toolbars/Tools.

(10) On the toolbar, click on the Zoom In tool . Using the new cursor, draw a square on the part of the world of interest.


(11) You can now adjust the zoomed layer using the Pan tool, i.e., move up, down, right or

left. Click on the Pan tool , click on the map using the new cursor, and move the cursor in any direction you want.

(12) Now you are going to label the features. You can label the features of any layer with

one of the attributes associated with it. For example, the Cities layer can be labeled with names of the cities. Before going into labeling the Cities layer, you will have to set the properties for labeling.

(13) With the layer zoomed, right-click on the Cities Viewed layer and then click on

Properties. In the Layer Properties window, click on the Labels tab. You can select what attribute of the layer should be used for labeling and the properties of the labels. Make sure that a check mark is inserted for Label Features in this layer, select Label all the features the same way for “Method:” and select NAME for “Label Field:.” Finally, click Apply and then OK to close the window.


(14) To see the attributes of a feature on the map, use the Identity tool. Pick any city, click

on the Identity tool , and select any city in the Cities Viewed layer.

(15) Now make the entire map appear by clicking on the Full Extent tool . Do not close this tutorial document because you will need it for the next section of the exercise.


2. Feature Attributes and Statistics

(1) You will now learn how to handle the attribute table associated with the layers. In the TOC, right click on the Cities Viewed layer and then click on Open Attribute Table.


(2) Scroll down through the table. There are 28 records – one for each city – and scroll across the table to look at the attributes. There are 10 attributes (fields). Observe the field OBJECTID, which contains a unique identification number for every record. See the Shape field, which has the entry Point for all the records because all the cities are represented by points on the map. The NAME field contains the names of the cities.

(3) Scroll back all the way to the left so that you can change the width of the NAME field.

Do this by moving the cursor to the vertical bar that separates NAME and CAPITAL so that the cursor changes from a single arrowhead to a double arrowhead. Start dragging the vertical bar on to the left until you begin to cut off the names.


(4) Now you will relocate the entire column. Highlight the entire column by clicking on the field name. Release the mouse button. Click and hold the mouse button on the NAME field and note that the cursor has changed. Drag the NAME field to left of the COUNTRY field. Release the mouse button. All the fields can be rearranged in the table in this way.

(5) As you have already seen, columns can be highlighted. Similarly, rows can be highlighted. This is called Selection. Move the cursor so that it is between NAME and COUNTRY and appears as a double-arrow. Double click in place to adjust the column width automatically.

(6) Select the New Orleans city feature by locating it using the NAME attribute from the

attribute table. In the table, scroll up or down and try to find New Orleans in the NAME field. Once you have found it, click on the left edge, which is shaded on the corresponding row to see that the whole row is selected in blue.


(7) Because you have selected a row in the table that corresponds to a feature, the feature is also selected in the map. Now, minimize the table and go to the map.


(8) To look at the selected feature closely, click on the Selection dropdown menu and select Zoom To Selected Features.

(9) Now clear the selection by clicking the Selection dropdown menu and selecting Clear Selected Features. Zoom to full extent by clicking on the Full Extent tool.

(10) Rows in a table can be sorted in ascending or descending order based on an attribute.

Sort the Cities Viewed attribute table according to elevation values. If the table is not already open, right-click on the Cities Viewed layer and then on Open Attribute Table.

(11) In the table, scroll to the ELEVATION field. Right-click on the field name and then in

the dropdown menu select Sort Ascending.


(12) You can see the statistics of the ELEVATION field by right clicking on the ELEVATION field name and selecting Statistics… in the menu. Look at the window that appears to view the statistics for this field. You may now close the Statistics window and attribute table, but do not close the ArcMap document.


3. Symbolizing Features Look at the TOC in the ArcMap document. Observe that below each layer name is a symbol associated with it. In this section of the exercise, you will learn how to change the symbology. Symbology can be changed in different ways. It can be defined by assigning a unique symbol to each feature or you can group the features of a layer and define a unique symbol for each group. There are other ways of symbolizing features.

(13) In the ArcMap document that is already open, observe that for all the features in the Countries have the same symbol assigned. You will now change the color of this symbol from default to yellow.

(14) In the TOC under the Countries layer name, right click on the symbol and a color

palette will appear. Select yellow. Click OK. The change in color will be immediately reflected in the map.


(15) Now that you have changed the color of the map, you will change the thickness and color of the country boundaries. Left click on the Countries layer symbol; this displays the Symbol Selector window.

(16) In the Options frame, change the Outline Width to 1 and change the Outline Color to

brown. Once you have done this click OK. You can see the change in the boundaries thickness and color.


(17) You will now change the symbology of the Cities Viewed layer. Left click on the Cities Viewed layer symbol. This displays the Symbol Selector window.

(18) In the symbol palette, select the Circle 2 type.

(19) With the window open, in the Options frame, change the Color to red and change the

Size to 10. Once you have done this click OK.


(20) Now you will change the background color of the data frame from blue to Cretean Blue. Right-click on the data frame (background) and then click on Properties.

(21) In the Data Frame Properties window, select the Frame tab and then select Cretean

Blue in the Background section of the window. Then click on Apply and OK.


(22) With ArcMap open, change the background of the data frame to white by following the procedure explained in the previous part.

(23) You can also change the symbology based on attribute values. First, you will make the

symbology based on unique values. For example, each country can be assigned a different color from the others.

(24) To change the symbology based on a unique value for the Countries layer, right click

on it and then click on Properties. Then, in the window that appears, select the Symbology tab.

(25) In the left-most box that is located under Show, click Categories and then in the

options below it, click on Unique values. You have to select the name of the field that will have the unique values. To do this, select CNTRY_NAME in the dropdown for Value Field. Next, click on the Add All Values button and then click Apply and OK. You can now see that each country feature has a different color.


(26) In the TOC, observe that the Symbol legend has a long list of symbols where it previously had only one value. To make the legend invisible, click on the minus sign located beside the layer name.

(27) You can try out other options for symbolizing, such as Unique values, many fields and

Match to symbols in a style to learn more about symbolizing features. Keep this ArcMap document open for the next section of the exercise.

4. Classifying Features Classifying features involves assigning the same symbol type to features that are grouped together based on a criterion. Criteria can be based on natural breaks (which is the default method), defining equal intervals (which creates classes of equal value ranges), and more.

(1) You will now classify the country features based on the population values. To change the symbology by combining features into groups, right-click the Countries layer and then click on Properties. Then select the Symbology tab in the window that appears.


(2) In the left-most box that is located under Show, click Quantities. Under the options

below it, click on Graduated colors. (3) Select POP_CNTRY as the field that will be used for classification from the dropdown

list. Leave the Normalization as none. Normalization could be used, for example, to classify the feature based on population density instead of population.

(4) You can change the number of classes of classification in the Classification frame. Click

Apply and OK. You should see that all the features take one of the five colors shown in the legend based on the population value. A value equal to -99999 is seen in the legend because the population of some countries is unknown. If the Cities Viewed layer is still labeled, remove the labels by right clicking on the layer and then removing the check mark for Label Features in the dropdown.

(5) Similarly, there are other options such as Charts and Multiple Attributes. Explore them

to learn more about classification of features.


5. Making Maps for Presentations In this part of the exercise, you are going to create a layout, which is the way to display the information that you infer using GIS. Usually, this would be the final step in a project.

(1) Before going into the details of how to create layouts, change the background of the data frame from white to light blue as explained previously, i.e., by using the Data Frame Properties window.

(2) Click the View menu and then click Layout View.

(3) On the layout toolbar, click the Zoom Whole Page button to view the layout properly.


(4) It is important to set up the page orientation before building the layout. You will use landscape orientation. Click the File menu and then select Page and Print Setup in the dropdown menu.

(5) Select Landscape under Paper and Map Page Size then click OK.

(6) Resize the displayed map by first clicking on it and then dragging the corners.


(7) The next step is to add a title to this layout. Click on the Insert dropdown menu and then select Title. A text box appears on the page that contains the ArcMap document name.

(8) To change the title, double-click on the text box to see the Properties box. Enter

Countries of the World under Text:. To change the font and size of the text, click on Change Symbol…. In the Symbol Selector window, select the font and size you of your choice, then select Apply and OK.


(9) Now you will insert a North arrow on the page. Click on the Insert dropdown menu and then select North Arrow…. A North Arrow Selector window appears. Click OK after selecting the symbol you wish to insert into your map. Drag the arrow to the location where you want it in your document.

(10) Now you will insert a scale bar. Click on the Insert dropdown menu and then select Scale Bar…. A Scale Bar Selector window appears. Choose whichever type of symbol you want to insert. You can change the units of the scale bar in Properties… Then, click OK. Drag the arrow to the location where you want it in your document.


(11) The next step is to insert a legend. Click on the Insert dropdown menu and then select

Legend. In the Legend window that appears, remove all the layers except Countries from the Legend Items list by selecting the removable layers and then clicking the arrow that points towards the Map Layers: list. Click Next.


(12) In the next step in the Legend Wizard, enter a title for the legend and select the font and size that you want. Click Next.

(13) Select the Border and Background of your choice. Click Next.

(14) Click Next again.

(15) Finally, to insert the legend, click Finish.

(16) Give the layout finishing touches so that it looks as shown in the following image.

These materials may be used for research and educational purposes only. Please credit the

authors and the Department of Civil Engineering, Texas A&M University. All commercial rights reserved. Copyright 2014: Texas A&M University.

data visualization - texas a&m university · 2014. 9. 22. · data visualization . francisco...

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