TEACHING GEOG 385.02/GTECH 785.02
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.
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.
Map document lists all of the
components associated with the project and lets you display any one or all of
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.).
Data sets are in:
C:\ESRI_Library\ArcGIS_Desktop\Getting started with ArcGIS.pdf
\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.
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.
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
Political units/municipalities (MUNICIP)
Factory locations (FACTORIES)
Public school locations (PUBLIC)
Begin by launching the ArcGIS program and creating a new map document.
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:
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).
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.
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.
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.