Introduction to Geographic Information Systems in Forest Resources

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Syllabus Schedule Class Meetings Assignments Course Data Internet Search Current Grades Contact Us CFR 590 Internet-only section Lab Locations

Objective:

• Become familiar with ArcView 3.x 's basic functionality and user interface.

READ AND UNDERSTAND THIS BEFORE YOU CONTINUE:

All of the pre-built projects used in the course will be available on the web at the course web site. In order to use any of these projects, you must

1. have the course CD loaded into the CD drive
2. have your removable disk loaded into the removable drive (or USB drive in the USB port), and know what drive letter it is assigned to.

Assuming you have these disks loaded, then you must open the cfr250.apr ArcView 3.x project file on the CD.

Failure to use the cfr250.apr project will cause problems, such as not being able to open projects, not being able to load data, or not being able to save your class projects in a way that they will be able to be opened later.

Even when you build projects from scratch in this course, you should use the cfr250.apr ArcView 3.x project file on the CD.

Steps:

1. Download a few files
2. Start ArcView 3.x
3. Open the with the Startup Project
4. Switch active windows
5. Alter drawing properties
6. Identify features
7. Use help for dialogs
8. Use context-sensitive help
9. Measure distances and areas
10. Get information about features
11. Display and modify a table
12. Display and modify a chart
13. Create a layout
14. Close the project

1. Download the site_index.dbf file into the main (root) directory of your removable drive. (Note: make sure the file you downloaded has the name site_index.dbf. Web servers and browsers can arbitrarily rename files. If the file has a different name, rename it to the correct name. If you do not know how to view file names and extensions, go through this short tutorial.)
   
   
2. Download the avsmpl.apr file and save it in the main (root) directory of your removable drive. (Note: make sure the file you downloaded has the name avsmpl.apr. Web servers and browsers can arbitrarily rename files. If the file has a different name, rename it to the correct name.)
   
   These files will be used a short time later in the exercise.

1. The location of the ArcView 3.x shortcut may vary from system to system. It should be in a path similar to this:
   
   
   
   
2. During the first lab session, you will be shown where the ArcView 3.x shortcut is on the computers in the lab.
   
   
3. When ArcView 3.x opens, a dialog may open with choices for what to do next. Click the radio button for as a blank project or close the dialog.
   
   
   
   The project will open with a single window (the Project Window, with Untitled in title bar) containing a few icons, a few menu choices, and a few buttons.
   
   
   
   If ArcView 3.x opens with the Welcome to ArcView 3.x GIS dialog, as shown below, cancel the dialog.
   

1. Make sure that the data CD is in the CD drive, and your removable disk is in the removable drive.
   
   
2. From ArcView 3.x 's File menu, select Open Project.
   
   
3. Navigate to the CD (note to change drives, use the Drives: dropdown list at the lower right of the Open Project dialog), and select the cfr250.apr project file.
   
   
   
   
   
4. If you do not have your removable disk loaded, you will see an error message:
   
   
   
   Insert your removable disk and click Try Again.
   
   
5. If there are more than 2 removable drives on the machine, you will need to select the drive you will be using:
   
   
   
   
   
6. If there are more than 2 CD drives on the machine, you will need to select the drive you will be using:
   
   
   
   
   
7. When the project opens, you will first be prompted to choose whether to create a new project or to open an existing project.
   
   
   
   Select Open an existing project (because you will be opening the project you just downloaded) and then click the OK button.
   
   
8. Navigate to the removable drive's root directory (you will need to change drives again). You should see the avsmpl.apr file that you just downloaded.
   
   
   
   Double-click the filename, or single-click and then click the OK button.
   
   
9. The avsmpl.apr project will open and automatically load data sets from the CD. You will see the project window on the left, containing several icons for the different document types. On the right side, you will see a View containing several different features.
   
   

Summary: You have just downloaded a few files from the course web page, including an ArcView 3.x project file and a dBASE table. You used the cfr250.apr project to open the downloaded project. This set of tasks will be performed during nearly every lab exercise during this course.

When the project opens, you will notice that the Pack Forest view is active. This means that its title bar is shaded in, and if there are multiple windows, it will be on top of the stack. Note that the GUI at the top of the ArcView 3.x application window has a specific group of menus, buttons, and tools. As you get more familiar with ArcView 3.x, you will instantly recognize the document type that is active by simply looking at the GUI menus, buttons, and tools.

1. Click on the title bar for the Project window (avsmpl.apr).
   You will notice that the menus, buttons, and tools are completely different from before. Each set of GUI components is specific to the type of document or window that is active.
   
   
2. Make a mental note of the change in the GUI. As you go through the exercises for the rest of the course, if you find yourself searching for a GUI control (menu, button, or tool) that does not appear to exist, make sure the correct document window is active.
   
   
3. When switching active windows, always click on the title bar for the window rather than in the body of the window. If you click in the body of a window, especially a table or view window, you may inadvertently cause some kind of action you do not want to perform, such as altering a selection on a table or changing the extent of a view.
   
   You can also switch active windows by selecting Window from the menu and selecting the name of the window you want to switch to.
   
   
4. Click back on the title bar for the Pack Forest view document window. Note how the GUI changes back to the way it was before.

Summary: You have just learned to switch active document windows. Much confusion will be spared if you learn to always be aware of which document is active, and what document type that window belongs to. Because GIS applications integrate different types of data, some of the different data types are stored in different document windows. You will need to learn to switch back and forth with ease. If you do not see a menu, button, or tool control you are looking for, make sure that the correct document is active.

1. The project opens with a map of Pack Forest. Notice that there are several themes (in this case, Streams, Roads, Stands, Boundary, Culverts) in the view document. Also note that streams do not display, since the theme is not checked "on."
   
   
2. Click on checkbox to the left of the Streams theme in the View Table of Contents to display the theme.
   
   
3. Now that all themes are turned on, notice that the points for the theme Culverts is not displayed. This is because themes draw in order, from bottom to top of the list of themes in the Table of Contents. Click on the Culverts theme name and holding the mouse button down, drag it up the list (above Stands). Now the points representing culverts should be visible.
   
   If you have themes loaded in a view and some do not appear visible as you think they should, check the drawing order.
   
   
4. Many of the Culverts are spaced so closely together that they are not discernible from each other at this scale. In order increase the scale to see the individual Culverts, click the Zoom In tool . The pointer will change to a magnifying glass when placed over the map display.
   
   Note that the cursor will always change to match the type of tool used. When you become familiar with ArcView 3.x, you will be able to tell which tool is active by looking at the cursor.
   
   
5. Click and drag a rectangle (click the mouse button down at one corner of a rectangle, and drag to the opposite corner, then release the mouse button) near the center of Pack Forest. Now you will see the individual culverts when the map redraws at the new scale.
   
   
   
   Now you can see the individual culverts, roads, and streams.
   
   
6. Click the the Pan tool . Place the cursor on the map view, then click and drag in any direction. When you release the mouse button, the view will redraw in its new position. You can use this to move to a different area of interest without zooming out and back in. A lot of time is wasted by zooming in and out unnecessarily, because after each zoom, the view needs to completely redraw.
   
   
   
   
7. There is a bank of 6 buttons on the button for controlling zoom. You have just used the Zoom tool. Now examine the zoom buttons:
   
   
   
   In order from left to right, these perform
   
   1. zoom to full extent of all themes
   2. zoom to full extent of active theme(s)
   3. zoom to selected features of active theme(s)
   4. zoom step in
   5. zoom step out
   6. go to previous extent.
      
      
8. Click the Zoom to active themes button , and you will zoom to the full extent of the Culverts theme. Because Culverts is the active theme, you will zoom to the extent of this theme. If several themes are active, you will zoom to the combined extent of all active themes.
   
   
   
   All the culverts are visible, but the rest of the view is truncated.
   
   
9. Now click the Zoom to full extent button () and the view will zoom to contain the full extent of all themes. If you have several data sets that represent the same area of the earth, but not all the data sets display as you think they should, zooming to full extent can show you if the data sets were built with the same spatial referencing framework.
   
   
   
   
   
10. Click the Zoom to previous extent button a few times to see how you can return to a previous display extent. You can only do this five times until the saved extents are used up.
    
    
11. Experiment with the Zoom in and Zoom out buttons to see how they are used.

Summary: You have learned to turn themes on and off, to make themes active, to alter drawing order, and to navigate around the view by zooming and panning. The more themes you have displayed, and the more complex those themes, the longer it will take to draw your view. For this reason, you should get very familiar with these zooming tools and buttons so that you can work efficiently.

1. To find out some cursory information about individual features, first make active the theme you are interested in (do this by single-clicking the name of the theme so that it appears raised). In this case, let's find out some information about the Stands theme.
   
   
2. Make the Stands theme active by single clicking somewhere on the Table of Contents in the area of the legend for the Stands theme. You will see that the Stands theme legend now has a "raised" or "chiseled" look. This is what is meant by the active theme.
   
   
3. Click the Identify tool in the tool bar. Move the cursor onto the map display of the view. You will see the cursor change from the pointer to the Identify cursor. The active area of the identify cursor is a 3-by-3 pixel window centered at the intersection of the crosshairs.
   
   
4. Click on one of the forest stand polygons. The Identify Results dialog will appear, listing the attributes of the stand you just selected. Click on a few more stands, and each successive stand will be added to the identify results window. You can click up and down in the Identify Results dialog to view attributes of already identified features.
   
   Using the identify tool is a good way to get a brief look at the attribute values for a selection of features in your spatial data sets.
   
   
   
   
5. Click the Clear button to remove the selected record. This allows you to remove the selected record from the identified set.
   
   
6. Next, click the Clear All button to remove all records.
   
   
7. Make another theme active (hold the <SHIFT> key down and click the name of another theme in the Table of Contents. You should see that both Stands and your other theme are active.
   
   
8. Perform another Identify. What do you see?

Summary: You have use the Identify tool to browse attributes for individual features. Use this whenever you are curious about the type of data you have, and what those data sets represent. If you are interested in the attributes of features at a particular location, the Identify tool is the right tool for the job.

Note: the active area of the identify pointer is a 3-by-3 pixel window. Any features that fall within this window will be identified. If you are zoomed out to a very small scale, a single click of the identify tool will result in many features being identified; in this case you may need to zoom in to a smaller area.

1. While the Identify Results dialog is still active, hit <F1> on the keyboard.
   
   
2. The Help topic for the Identify tool will open.
   
   
   
   
3. Read through the help topic.
   
   
4. Close the Identify Results dialog.

Summary: You have just opened the Help topic for an active dialog. Whenever a dialog is open, you can use the <F1> key to open the help topic describing the dialog and all of its options. We will be dealing with a large number of dialog boxes that server many different purposes. Some of these dialogs are quite complex, with multiple controls. You should always read help topics on dialogs if you have any confusion or questions about functionality.

1. Click the context-sensitive help button and then click anywhere on the view. Help will open with the topic "What is a view?"
   
   
   
   
2. Follow the hyperlinks to move forward, and use the Back button to return to your original topic.
   

Summary: You have just learned how to open context-sensitive help. Use this whenever you want to know more about different parts of ArcView 3.x, such as a document or button.

Here we will cover how to measure distance and area in a view. We will start by measuring the distance from one end of the forest to another.

1. To go back to a smaller scale extent, make Stands the active theme (single-click in the theme's name in the Table of Contents) and click the Zoom to active themes button .
   
   
2. Click the Measure tool . The pointer will change to an L-square, and when you click on a location, you will see a line between the place you clicked and the pointer. You will also notice that the status bar reports the length of the line.
   
   
3. To change the line's shape, single click again on the view. As you keep clicking, the shape of the line will change, adding a vertex at each point where you click.
   
   
4. As you click, glance frequently at the Status Bar at the bottom of the application window. The status bar will report the length of the current segment as well as the total length of the line.
   
   
   
   
5. To finish the line, double-click on the view, or hold the <CTRL> key and single-click the mouse.
   
   
6. You can also measure area of shapes by creating shapes using the Draw tool . The draw tool is a composite tool containing a dropdown list of individual tools, which allows you to add various different graphical primitives to the view. When you add polygonal shapes to the view, their measurements are reported in the status bar.
   
   
7. Click and hold the draw tool until it drops down, then select the Rectangle draw tool , add a box, and watch as its area changes as the size of the box changes. Press the <DELETE> key to delete the box. You can also use the Polygon draw tool to estimate the area of irregularly-shaped areas, or the Circle draw tool to estimate the area of circular regions.
   
   
8. If you have created a large number of graphical objects, you can delete them all by selecting Edit > Select All Graphics from the menu, and then hitting the <DELETE> key.

Summary: You have just measured lengths and areas on a view. This is similar to using a measuring wheel or a dot grid or planimeter on a map, but this method is faster, easier, and potentially more accurate. One of the biggest differences between using this method and using a planimeter or other manual tool is that the line or polygon you have used to measure length or area is visible; after using a map wheel or planimeter, there is no traced outline on the paper map. Making simple measurements is one of the basic functions of a GIS. We will work later at getting more precise areas of polygonal features such as vegetation patches.

Next, we will find features within themes based on text-formatted attribute values in the theme tables.

1. With the Stands theme active, click the Find button . The Find Text in Attributes dialog will open. Search for a stand whose name contains the word "bethel" (one of the formed Deans of the College of Forest Resources was named James Bethel, for whom the stand is named).
   
   
   
   
   ArcView 3.x searches for all attributes in the active theme's attribute table, and selects any features whose text attributes contain the text you typed in. You will see the stand selected (shaded in yellow) whose name contains the word "bethel," and the view will be centered on the selected feature. Searches using this method are case-insensitive, so this method will match any text string containing the letters "bethel," "Bethel," or "BETHEL.".
   
   
   
   Clicking the same tool finds the next stand matching the name search:
   
   
   
   Use the Identify tool to find out the names of these forest stands. You will see why they matched in the text attribute search.
   
   A third attempt will result in no more matches. The reason for this is that the Find button searches only once through the attribute table. When it reaches the end of the table, it does not start again at the beginning. This prevents you from continuously cycling through a large table.
   
   This method is good for finding features if you already know something about the data set's attribute values. The tool is only useful for searching for text attributes (numeric attributes cannot be searched in this manner). Of course, if you have no idea what text values are in the table, this method of finding features will be of little value.
   
   
2. Another way to select features is by using the Select tool . Click on single features or click and drag a rectangle. Any features that are clicked or which fall partially or completely within the rectangle will be added to the selected set. Your selection may vary, but it should look basically like this:
   
   
   
   When clicking features, the active area of the select pointer is a 3-by-3 pixel window. If you are zoomed to a very small scale, clicking on a single feature may result in too large of a selection, and you may need to zoom in closer.
   
   
3. Once you have selected a group of features, open the theme's attribute table with the Open Theme Table button . The theme's attribute table will open, with several records selected (the selected records, shown in yellow, represent the selected stands in the view). The table contains a single record for each single stand polygon. The records contain various pieces of data about the stand.
   
   
   
   
4. You may see only a few records selected, or none at all depending on what polygons you have selected. To view all selected records, click the Promote button . This will temporarily promote selected records to the top of the table (the file on the disk is not altered by the selection or the promotion).
   
   
   
   
5. The section of the course on tables will delve deeper into making selections using tabular queries. For now, unselect the selected records by clicking the Select None button .

Summary: You have just searched for features containing specific values, selected features and looked at their values, opened a theme table, and promoted records. This is the beginning of our exploration of the relationship between the coordinate features of a theme, and the tabular records of the theme's table. Nearly all of what we will do in GIS will take advantage of the relationship between theme coordinate and tabular databases.

Tables can be modified in their display properties. Fields can be hidden, renamed, resized, and the order of records can be changed. Often, data developers give fields cryptic names that are not easy to work with. If this is the case, you can change the text for a field's name display.

1. Make the Attributes of Stands table active, and select Properties from the Table menu.
   
   
2. The table's properties will be displayed in a dialog. Each field is listed, with a Visible check, the Field name, and field Alias. To hide fields, uncheck their Visible property check box. To change the display name of a field, enter text in the Alias box.
   
   
3. Uncheck several of the fields.
   
   
4. Scroll down to the item Age_class_2003, and enter "Current Age Class" in the Alias box.
   
   FIX THIS
   
   
   1. While you are here, hit the <F1> button on the keyboard. This will open the help topic on the Table Properties dialog. The help topic will describe the overall functionality of the dialog as well as the different controls on the dialog.
      
      
      
      
   2. Close the Help topic.
      
      
5. When you OK the change, you will see the table's display change accordingly. These changes are temporary to the ArcView 3.x project, and do not change the files on the disk. This means that if you open the data set in another project, or even again in the same project, it will appear the same as it did before you made these recent changes.
   
   This can be very handy if you get a theme with a table that contains many attribute fields, but you are interested in displaying only a few fields.
   
   
6. Now sort the table according to the Current Age Class item. Click on the item's name in the table to make it the active item (it will appear pressed in), and then click the Sort Ascending button . As you scroll, note how the table is sorted. You will see that the table is sorted by alphabetical value, rather than numeric value (e.g., 190 < 20 in alphabetical order). This is because the age class field is a character field, rather than a numeric field. Be aware that the field type will affect what type of functions can be performed on the field. We will look at fields in more detail later in the lesson on tables.
   
   
7. Make the Age_2001 field active, and click the Sort Ascending button again, and the records will be placed in the correct order.
   
   
8. Close the theme table, make the view active, and zoom to the full extent of all the themes by clicking the Zoom to Full Extent button . Now close the view by clicking the X at the upper right of the view window.

Summary: You have just opened a theme's table, and altered its properties (turned field display off, altered the field name alias) . You have also sorted the table's records. None of these changes affect the table's file source on the disk.

1. Make the Project window active, and single click the Views icon to highlight it. This will switch to the Views document list. (If you have double-clicked, this will create a new instance of a view, called View 1, View 2, and so on. Don't worry, just close any of these new views).
   
   
2. Double-click on the Stands view to open it. The view shows Pack Forest's forest stands. The stands are classified into 5 natural-break classes based on the Site_index field in the feature attribute table. (For those of you that do not know, site index is an estimate of the height of a tree at 50 or 100 years for a particular area; the larger the site index, the more productive the location.)
   
   
   
   
3. Open the theme table for the Stands theme. Note the item Site_index. I have prepared a summary table of the theme attribute table, in which the area per site index value is summed. This table is saved as Site Classes. The actual file represented in the table is the site_index.dbf dBASE file you downloaded earlier.
   
   
4. Open this table by single clicking the Tables icon in the project window, and double clicking the Site Indexes table. I have also prepared a chart which graphically represents the tabular data.
   
   
5. Open the Site Index Summary chart as well. The chart shows the relative proportion of one class to the others. You can see the area (in both square feet and acres) of each site index class.
   
   
   
   
   
   
6. Change the format of the chart into a pie chart by clicking the Pie Chart button .
   
   
7. Select the first chart style at the left of the gallery and click OK.
   
   
   
   Now your data show the relative proportion of area of each site class to the entire forest.
   
   
   
   
8. The problem with this chart is that the colors on the chart do not match the colors on the map in the view. It is difficult to see the spatial arrangement of the classes summarized in the chart. Finally, you will change the display properties of the view to match the colors of the pie chart. Presently the view displays site classes in a green monochrome color ramp, but we want the colors in the view to match the chart.
   
   
   1. Download the file site_index.avl (place it in the root of the removable drive). (Note: using the Windows Explorer, make sure the file you downloaded has the name site_index.avl. Web servers and browsers can arbitrarily rename files that have been downloaded. If the file has a different name, rename it to the correct name.)
      
      
   2. Double-click on the Stands name in the view table of contents (or click the legend editor button ) to open the Legend Editor.
      
      
      
      Currently the legend displays the Site_index field in 5 classes, using a green monochromatic color ramp.
      
      The legend editor is used to alter the display of themes. It is used to change colors, symbols, and classes. We will use the legend editor extensively in this course for altering the display and symbolization of themes.
      
      
   3. Click Load in the Legend Editor, and select site_index.avl. Make sure the Field is Site_index, check the All checkbox, and then OK the Load Legend dialog.
      
      
      
      You are loading a pre-prepared ArcView 3.x legend file that will alter the colors of the display for the Stands theme. If you create a customized legend for a theme and you wish to use that legend over again, you can save it in one project, then load it in another. This saves the time of re-creating the legend from scratch.
      
      
   4. Click Apply in the legend editor, and then dismiss the Legend Editor.
      
      
9. Now you can see not only the relative proportion, but also where the different site indexes are distributed across the forest. White polygons are unclassified or are outside the administrative boundary.
   
   

Summary: You have just looked at a chart and altered its properties. Charts are used to make numeric data more easily understood. You have also downloaded a ArcView 3.x legend file to load a predefined classification and legend for a theme. Later, you will learn to alter the theme legends on your own.

In a map layout, you can place graphical elements containing views, charts, tables, and graphical primitives on a page. The layout can then be sent to a printer or plotter, or saved as a graphics file. This step will create a simple map from the site index view.

1. Make the Stands view active, and then select Layout from the View menu.
   
   
2. Double-click the Landscape icon in the Layout Manager.
   
   
   
   
3. The landscape layout template automatically places all of the map elements on the page, including the view, a title, legend, north arrow, and scale bar. The grid is used for placement of graphical elements.
   
   

Summary: You have just created a simple map layout using a built-in layout template. As you know, one of the main uses of GIS is to create maps. This automated method of creating a layout results in a map that is too generic for most purposes. We will spend one class session on creating and modifying layouts later in the course.

You can use the method described for creating PDF files to create PDF files of map compositions for distribution via e-mail or the web.

You have just experienced a cursory view of what ArcView 3.x has to offer. Each of the topics covered in this first exercise will be covered in greater detail later in the term.

For now, close the project by making the project window active, and selecting Close from the File menu. When asked if you want to save the project, click Yes.

Open a Windows Explorer and view the contents of the removable drive. You should see the project you just downloaded and modified (avsmpl.apr), the dBASE file you downloaded (site_index.dbf), and the legend file (site_index.avl). Get used to looking at the file system and knowing what files represent what data sets.

Syllabus Schedule Class Meetings Assignments Course Data Internet Search Current Grades Contact Us CFR 590 Internet-only section Lab Locations

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