TEACHING GEOG 385.02/GTECH 785.02 
GIS APPLICATIONS IN SOCIAL GEOGRAPHY
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Intro to ArcGIS Hands-on Demo

This demo consists of two parts. Part I explains ArcGIS basics. Part II includes tutorial exercises that came with ArcGIS. Part III includes displaying the data set that later will be used in vector competency exercises.

 

Part I. ArcGIS basics

 

General structure

 

ArcGIS consists of several components.

ArcCatalog is a database management utility. It allows to organize spatial layers, the attribute tables and other parts of a geographic database.

ArcMap is a display or visualization utility. It helps to display layers and their attributes. It also allows to query the database and compose maps.

ArcToolbox is the analytical block. It allows to perform spatial analysis on the geographic layers (geoprocessing). Toolbox functions can be accessed from ArcCatalog and ArcMap.

ArcInfo Coverages are topologically encoded vector files. Shapefiles are feature encoded, with a spatial index added. Each shapefile consists of several files: geometry of features is in *.shp; attribute table is in *.dbf file, and spatial index is in *.shx.

Maps (map documents), views, themes, tables

Map documents (*.mdx) store paths to displayed data layers and their graphic rendition. The layers can stay in their original places and in different folders. The map document keeps track of where everything is stored and how it should be displayed.

      • This is in contrast to IDRISI because Idrisi map compositions store graphic information and not the paths. Idrisi likes to have all files in the same place that is indicated in ENVIRON. Only default palettes and symbol files are stored in Idrisi own folders and it knows where to find them.
      • We will not create nearly the number of output files in ArcGIS as we created in IDRISI, because in ArcGIS changes are saved to the existing files and most manipulation is done in attribute tables.

 

Map document lists all of the components associated with the project and lets you display any one or all of them.

NOTE: Menus in ArcGIS are context sensitive (in Idrisi - constant), which means that they change depending upon which component is in focus (view, table, layout, chart, etc.).

Part II. Exploring ArcCatalog and ArcMap

Data sets are in:

C:\arcgis\arctutor

 

Exercises:

C:\ESRI_Library\ArcGIS_Desktop\Getting started with ArcGIS.pdf

 

And

 

\scratch\GISSG\ Getting started with ArcGIS.pdf

 

Open the text of the exercise Getting started with ArcGIS.pdf. Read Chapter 1 and do the tutorial from Chapter 2. The data for tutorial is in C:\arcgis\arctutor.

Part III. Hands-on demo

Download CompExAv.exe data from BB (right-click save as… then double-click to explode the compressed file). Make sure it is in your U: drive.

Data DISPLAY

Explore the layers that will be later used in competency ArcGIS exercises. You will practice displaying of data and working with symbolism in ArcGIS. The data consists of the following layers of information for one area of New Jersey:

Landuse (LANDUSE)
Political units/municipalities (MUNICIP)
Streams (STREAMS)
Lakes (LAKES)
Roads (ROADS)
Factory locations (FACTORIES)
Public school locations (PUBLIC)

 
Begin by launching the ArcGIS program and creating a new map document.

    • Go to Programs: ArcGIS: ArcMap icon to begin the program.
    • When ArcGIS opens it displays an empty map document window called UNTITLED. Any map document can have several data frames into which you place layers of information. These are within the window on the right. The window on the left contains the table of contents for your map document. Other items can also be added to map documents (e.g. charts, graphs, text boxes, etc.). You will be working with only single data frames.

Adding and Displaying Data Layers:

You now have a new (empty) map document open called untitled. Within the default data frame within that map document you can display several layers. Do the following to explore the data (layers) provided:

    • Go to ADD DATA in the main file menu (or use the add data icon).
    • Locate the data provided by connecting to the root directory c:\ and then navigating to c:\_scratch_gis.
    • Select the layer called LANDUSE.SHP (note the rest of the data). The landuse layer is now within the data frame called LAYERS and displays with a default symbol.
    • Repeat this procedure to add these other map layers: FACTORIES, STREAMS, LAKES, PUBLIC, and MUNICIP.
    • View each theme one by one by turning off all other themes (click off the check mark to the left of theme names that you do not want to see and click the check mark on for just one theme).

Note that "checked" Layers will be displayed in the order they are listed. So, if you display 2 layers at one time, the one closer to the top of the list will display on top of the layers that is lower on the list. You can change the order of the layers by clicking on the name of a layer and dragging it to another position in the list. 

 

Try placing the LAKES at the top of the layer list and then displaying LAKES and LANDUSE at the same time. Also, practice zooming in and out using the magnifying glass icons and other options under the TOOLS toolbar item (if the tools toolbar does not automatically display, click on VIEW/TOOLBARS and turn on the TOOLS toolbar).

 

Symbology:

The layer LANDUSE is displayed using only one color even though it is made up of several different landuse categories. It would be better to create a legend that displays the names of each class/category within this landuse layer and then assign a unique color to each. To do this you will use the Symbology dialog.

    • Right click on the word LANDUSE in the table of contents and then select  Properties to see all of the properties associated with the selected layer.
    • Click the Symbology tab. The Symbology tab shows what is being displayed and what symbol is being used to represent what is being deplayed.
    • There are five groupings of what can be displayed with particular symbols. They are the vector features themselves, some categorical data from a attribute table, quantitative data from an attribute table, charts, and multiple attribute schemes that use combinations of symbols.
    • The first, features, is the default. On our map, all landuse features are represented in the same way using a single symbol.
    • The categories option is for qualitative or categorical data where unique categories are given unique symbols designed to differentiate (similar in concept to the use of qualitative palettes in Idrisi). The quantities option is for quantitative data and the assignment of symbols denoting change in value (similar in concept to quantitative palettes in Idrisi). The chart option is used to place small charts in each feature showing several attributes and the multiple attributes option uses multiple symbols for multiple attributes for each feature.
    • On our landuse map we wish to map categories of landuse and give them unique symbols. Select the first of the categories options, unique values.
    • Select a values field that will be the basis for the map. Now click on the values field down arrow. Note that there are several value fields (attributes) you could choose to display in the legend. These are attributes stored in a separate table that are linked to each landuse polygon (feature). The field with the names of each landuse category/class is called CLASS. Change the values field (the field with the values that you wish to display) to CLASS.
    • Now that the field is chosen, we need to choose which CLASS values do we wish to display. Choose to map/display all possible CLASS values by clicking on ADD ALL VALUES.
    • 6 classes of landuse appear with unique colors associated with each. You an change the COLOR SCHEME to some palette of your choice. The color scheme choices appear to be a mixture of qualitative and quantitative palettes. Be sure to choose a qualitative palette.
    • Click on APPLY and then OK.

Like the landuse layer, you can also select any attribute from the MUNICIP theme to display using Symbology. In this case, however, we are interested to explore the display of quantitative data.

o   In the table of contents check off your landuse layer and check on the municipalities layer.

o   All features are displayed using the same feature.

o   We wish to display the quantitative attribute data POPDEN90_S which represents population density in 1990 for each municipality (people per sq. mile).

o   Since this is quantitative data, select to the symbology for quantities. There we will use graduated colors to symbolize the population density data by municipality.

o   Again choose the field that you wish to map (i.e. POPDEN90_S) and select a color ramp that is appropriate (color ramps are continuous color palettes for quantitative data representation).

o   Finally, specify a classification scheme. The classification scheme is the method by which the continuous data will be grouped into categories or classes (this is equivalent to RECLASS in Idrisi but here the underlying data is not altered, only the display).

o   Click on CLASSIFY and a new dialog box appears with a histogram of your data, basic statistics relevant to the data, and how the data is to be classified.

o   There are several methods of classification. Explore the differences between Equal Intervals and Natural Breaks (note were breaks occur in the histogram). Also, explore changing the number of classes.
 

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