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Intro to ArcView Hands-on Demo

From DataLinks page download Demo8

ArcView Basics

A. Projects, views, themes, tables

Projects basically store paths. When you open files, they can stay in their original places and in different folders. The project keeps track of where everything is stored.

• This is in contrast to IDRISI, which likes to have everything all in the same place that is indicated in ENVIRON.
• Also, we will not create nearly the number of output files in ArcView as we created in IDRISI, because in ArcView changes are saved to the existing files and most manipulation is done in attribute tables.

Projects contain views, tables, charts, layouts, scripts – all possible components of the project.

• Views: Combinations of themes and their display characteristics (legends, colors, text annotation, etc.). They are interactive map displays.
• Themes: This is a layer (like in Idrisi). Each theme is composed of features and its associated attribute table.
• You can display one map per view but compose this map from multiple themes (layers) that describe the same territory.
• Tables: Attribute data associated with map layers (themes).
• Charts: Graphic representations of tabular data (pie charts, bar charts, etc. that have been saved).
• Layouts: A combination of any other components for display or printing (e.g. a view of map alongside a table of attributes set up nicely for output to a printer). You can insert several views into one layout.
• Scripts: Similar to macro commands. In ArcView they let you not only string together commands but also customize the interface and other functions.

The project lists all of the components associated with the project and lets you display any one or all of them.
NOTE: Menus in ArcView are context sensitive (in Idrisi - constant), which means that they change depending upon which component is in focus (view, table, layout, chart, etc.).

B. Displaying multiple themes and an image

Launch ArcView and open a new THEME

· Double click on the ARCVIEW icon

· Maximize the ARCVIEW Window by using the middle icon on the upper left of the window

· Notice that a PROJECT opens automatically. It is untitled and has no components (highlighting each component should show the list of that component).

· The main menu is very limited at this point (FILE, PROJECT/PROPERTIES, HELP). Check out HELP on PROJECTS (project components, project properties).

· Click the NEW button in the UNTITLED Project Window to make a new view (or double click on icon).

· A new VIEW appears titled VIEW1. It is empty (no themes/layers yet). Go to HELP on VIEWS (various topics).

· Notice how the menu items change. Now there are menu headings for both VIEWs and THEMEs.

Display map layers in the Map View (now called VIEW1).

· In the main menu choose VIEW/ADD THEME (remember, a theme is the spatial data for some set of features).

· Let’s us select where to get feature source data. Change directory to D:\idrisi32 tutorial\classdata.

· Hold the shift key down and click on the following files: BLDGS, LIGHTS, SEWERS, WATERLN. Click OK.

· All 4 themes are now listed in the VIEW (on the right). The names of each theme are listed along with the legend (note that there is a legend for each theme: lines, point symbol, and polygon).

· One of the four themes will be "active." The active theme will look "popped up." This means commands/actions in the THEME section of the main menu will operate on the active theme. In other words, this theme is in focus.

· Make buildings active. THEME/PROPERTIES (source, comments, etc.)… THEME/HIDE SHOW LEGEND…

· THEME/TABLE shows the associated attribute table for the active theme. Close table…

· To see the theme itself (displayed using the legend) click the check box next to the name of the theme in the VIEW (or VIEW/THEMES ON). You can display themes whether they are active or not.

Zooming, etc. (interactive display features)

· You can examine your displayed themes by zooming in a variety of ways…

· First you can change the size of the VIEW box itself (maximize?).

· In menu VIEW/ZOOM IN, ZOOM OUT, ZOOM TO THEMES, FULL EXTENT…

· Icons that are similar: magnifying glass lets you point and zoom or draw a box and zoom. Also hand icon is useful…

Add an image as a theme.

· You can add a raster image as a theme. However, it cannot be used for analysis, only visualization (opposite of Idrisi?). A special fairly new ArcView extension Spatial Analyst makes use of raster files for analysis.

· VIEW/ADD THEME and select where to get image source data. Select AIRPHOTO.BIL as the theme.

· Display the airphoto layer by checking the box.

· Since the layers draw beginning with the bottom one in the list (so the one on top is on the top of the display) the airphoto covers everything up. You can re-order themes by clicking and dragging. Move the airphoto down to the bottom of the list. (Is it similar to our CARSI NYC map project?).

Show database (attribute table), note change in menu.

· Make BLDGS active.

· Choose THEME/TABLE. A table appears and says "attributes of bldgs.shp". Note the different fields in the table. Each row (record) corresponds to a feature. This table is relational - the integrity of rows and fields is preserved. They are associated with vector features in the theme.

· When the table is in focus, the menu is different than when VIEW is in focus…

· When table is in focus: TABLE/PROPERTIES… TABLE/CHART (this data set isn’t very good for that, we’ll do this later).

CLOSE EVERYTHING (asks to save project, no…)

C. Create a Legend that displays multiple classes and colors

Go to the FILE menu and choose NEW PROJECT. The project box opens and is empty.
Associating data with colors is called classification in ArcView. The concept is similar to autoscaling of data in Idrisi32. In both cases, data is divided into certain number of classes according to a selected color palette. Note that this is done for display only and the underlying data (in a raster image or in a vector attribute table) remain intact.

Create a new VIEW that contains the theme called COUNTIES.

• In the untitled project window, choose NEW VIEW
• VIEW, Add Theme, feature data source, D:\idrisi32 tutorial\classdata, COUNTIES.
• Display COUNTIES by checking the box. Note that all counties are displayed using the same color.
• Go to THEME/TABLE and note all the data associated with these counties (population, income, homes, race – all for several times).
• We could map any of these attributes using a variety of color schemes (palettes, both categorical and continuous/quantitative data in the table).

Select the Legend Editor

• Double click on COUNTIES or select THEME/EDIT LEGEND.
• The edit box opens. The theme and leged type are displayed. By default, ArcView displays all data with the same (single) symbol using randomly chosen color.
• Click on arrow to see other types of legend. Unique value offers a color scheme of contrasting colors (good for qualitative data). Graduated color offers a color scheme of blending colors (good for quantitave data).
• Select Unique value legend and NAME as the field from the drop-down list of fields. ArcView produces an automatic palette for categorical data.
• Select POP_98 as the field. Clearly, we need to change this to a quantitative palette. Select Graduated color as a legend type. Now population data is correctly displayed with a quantitative palette. ArcView also automatically assigns data ranges to each color (classifies that data into 5 bins by default).

Create unique value legend (categorical data/qualitative palette) showing county names

• Change LEGEND TYPE to Unique Value (categorical data).
• Change VALUES FIELD to Name (the field of data we are interested to display).
• Change COLOR SCHEME to MINERALS (or whatever one you like). This is a qualitative palette.
• Click on APPLY. Now you can see each county with a unique color as well as the names of each county in the legend (THEME/HIDE SHOW LEGEND…).

Create graduated legend (continuousdata /quantitative palette) showing population.

• In the Legend Editor select LEGEND TYPE to be Graduated Color.
• Set the CLASSIFICATION (not VALUES?) FIELD to be POP_93.
• Select a COLOR RAMP (not COLOR SCHEME?).
• APPLY. Now you can see the continuous data of population displaying using a quantitative palette.
• Note that ArcView automatically classified the data into 5 categories (like RECLASS in Idrisi but does not produce a new data layer of data or if you autoscaled data to 5 color range).

You can, using the Legend Editor, reclassify your data very quickly (for display).

• Click on the CLASSIFY button in Legend Editor.
• Change number of classes to 3, press OK, then press APPLY.
• Double click in the VALUE field and write in 0 - 49999, 50000 - 100000, 100001 – 663995.
• APPLY.

D. Cursor Inquiry to Explore Data

The cursor (like in Idrisi) can be used to explore data. In the case of ArcView we can use the cursor to see all of the attributes associated with a particular feature.

• Click on the icon that looks like the international symbol for information ("i").
• Your cursor should look like the same symbol.
• Go to a county you are interested in and click. The Identity Results dialog appears.
• It contains all attributes for county on the right and it will list all of your queries on the left…
• It lets us view all of the tabular data by feature (record)… This is data base query by location…

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