Getting oriented

When you launch a new ArcMap session you get a blank window with legend on the left and map frame on the right. 
The easiest way to learn this software is by playing with it.  Check out the menu options and tools; see what mouse-clicks bring up.
Since this software uses a lot of system resources, you should not run more than one ArcMap session at a time. 

When you add data layers to a data frame, they are listed in the legend and displayed in the map. 
The properties menus contain tabbed settings windows. 
Access the dataframe properties by right-clicking on the map or the dataframe name in the legend; use it to select an appropriate coordinate system for your map. Access each data layer's properties by right-clicking on the layer name; use it to set appropriate symbology for each layer. 


You will usually see the "standard" and "tools" toolbars, and can access many other specialized toolbars by right-clicking on any blank area of the project frame.  You can drag and drop toolbars wherever you want.

ArcCatalog launches as a separate window.  Because each shapefile is actually many files, you should use ArcCatalog to copy, move or rename shapefiles, rasters or or to edit their properties.  If you use Windows directory listings to mess with individual component files you will likely corrupt your data.  Likewise, you should use ArcCatalog to manage rasters, which are actually subdirectories full of mysteriously-named files. 

ArcTools is a large library of specialized GIS modules.  If you launch it, the ArcTools directory will typically appear in a frame between the legend and map. 

Some long-time GIS'ers who cut their teeth on the old ArcINFO still work off the command line, where you type in module name and their relevant parameters. The Help menu includes the module syntaxes and extensive documentation, and some specialized functions may only be available only via command line.  We won't be needing the command line in this course. 

Most useful basic menu elements

File menu: save the current state of your project; open a saved project; export your map as a graphic file (for inclusion in your project web page). 
Edit menu: copy map to clipboard (can paste into Adobe Photoshop or Paint).  ArcMap's un-do capability is limited.
Insert menu: add cartographic elements (text, legend, scale bar, north arrow, etc.) to your map.  You must be in "Layout" view, not "Data" view, to add most of these.
Selection menu: select particular features from one or more layers by their attributes and/or by their spatial relationship to other features. 
Tools menu: activate extensions such as Spatial Analyst (for raster data) or 3D Analyst (for TIN's and 3D viewing); generate graphs or reports.
Window menu: activates separate map overview (full extent) and/or magnifier (zoom) windows; restores your legend frame if you accidentally close it.
Help (F1) ...if it works (in prior years it has sometimes causes lab machines to crash).  The Contents tab has information arranged by topic; otherwise use the Index to research a specific term.

GIS data formats

The successive projects in this course will introduce various types of map data that ArcMap can handle:

• The first project uses vector shapefiles.   Each shapefile contains discrete data features of a single type, either points, lines, polylines or polygons (as shown in the graphic above). 
  
• The second project will use lots of raster data that represent map features as sets of uniformly-sized grid cells or pixels.  Rasters require use of Arc's Spatial Analyst extension, accessed through the Tools menu.  Rasters are most appropriate for modeling continuous surfaces, such as terrain elevations.  You will also use georeferenced airphotos, which can be used as multi-band rasters.  The Spatial Analyst lets you convert data from raster to shapefile or shapefile to raster.
  
• The third project involves some fieldwork with a GPS receiver, and you will download your field data as shapefiles and edit these as necessary.  This project introduces some 3D formats supported by the 3D Analyst extension, including 3D shapefiles and Triangulated Irregular Networks (TIN's) that model terrain as connected triangular facets.
  
• The fourth project uses all of these formats.  It involves analyzing a watershed, georeferencing and analysis of a satellite image, and development of efficiently-targeted runoff control strategies to protect stream quality. 
  

Shapefiles are the most commonly-used GIS data format.  Each shapefile is actually a set of files on your disk; for example, the "states" shapefile has component files "counties.avl," "counties.dbf," "counties.prj," "counties.sbn," "counties.sbx," "counties.shp," and "counties.shx."  The three most essential components are the ".shp" file which stores the basic cartographic data, the ".shx" file which indexes the cartographic data as features, and the ".dbf" file which is a dBase-format attribute table for the geographic features.  

Each shapefile has an associated attribute table that contains one record for each individual feature, and one or more data fields that store attributes of the features.  Each raster has an associated attribute table that contains one record for each raster category value.  This means that ArcMap treats all the raster cells in a particular attribute category as a single feature, even if they are geographically dispersed. 

Access a layer's attribute table by right-clicking on it and choosing "Open Attribute Table."  You can create new data fields in the "Options" menu.  Field types include short and long integers (no digits to the right of the decimal point!), single- or double-precision numbers (including digits to the right of the decimal point) and text.  If you right-click on a field name, you can sort the records according to that field, summarize the data by field value, calculate new field values or extract summary statistics for that field. 


Selecting features

You will often want to focus your analysis on specific features in a shapefile, or specific cell categories in a raster.  There are multiple ways to select individual features or sets of features from the map or attribute table:

• Click the select tool  and use the mouse to click individual featurs or drag a box touching multiple displayed features on the map.  Hold the Shift key down to make multiple selections.  If you are using multiple shapefiles, use "Set Selectable Layers" in the Selection menu to specify which shapefile you are selecting features from. 
  
• Use "Select by Attribute" to select features whose attributes meet some specified criterion.  For example, to select the five Great Lakes you could select the lakes with AREA >= 7500 square miles.  Click the "Get Unique Values" button to see all the field values.
  
• Use "Select by Location" to select features in one layer that have some positional relationship to features in another layer, e.g., contain, are contained by, intersect, are within a specified distance of, etc. 
  
• Select a feature from the attribute table by clicking the little box to the left of the feature's attribute table record.  Hold the Ctrl key down to make multiple selections.   Selecting by attribute records is easiest when you can sort on a field so the desired records are all grouped together.
  

And note that there are multiple selection strategies:

• create a new selection
• add features to an existing selection
• select a subset of features to retain from an existing selection
• select a subset of features to remove from an existing selection

So if you wanted, you could select all states with areas greater than 50,000 square miles that are not within 500 miles of the Mississippi River, and have names that begin with the letter "A."  [Select by attributes from states (new selection): AREA > 60000; select by attributes from rivers NAME = "Mississippi"; select by location (remove from currently selected) states that are within 500 miles of (selected) rivers; open states attribute table, click "Show: Selected" box, sort by name.  Answer: just Alaska and Arizona.]

Pay attention to which features you have selected.  If some of the features in a shapefile are selected, many modules will operate on those features only.
For example, if you...
Export the shapefile's features or attribute records to a new shapefile, only the selected features or their attribute records will be exports;
Calculate summary statistics on an attribute field, the statistics are only calculated for the selected features;
Use the features as targets for Spatial Analyst's Distance module, only the selected features will be used as targets.
It is good practice to "Clear Selected Features" when you no longer need them selected. 

A note on projections

You will be required specify an appropriate coordinate system (via the data frame Properties tab) for every map you include in your submitted projects.   We will discuss projections and coordinate systems soon.   Briefly, a projection translates spherical (lat-lon) coordinates to a planar coordinate system such as UTM or State Plane.   ArcMap can display unprojected (lat-lon) data in any specified coordinate system, and can even reconcile shapefiles in different specified projections within the same map.  But projection inconsistencies can confuse some analytical modules.

The actual coordinates of a shapefile are stored in the ".shp" file.  There may be a companion ".prj" file specifying what coordinate system that is; otherwise ArcMap may guess.  A lot of shapefiles use lat-lon decimal degree coordinates, since that was the default coordinate system for ArcView 3, the popular precursor to Arc 9. 

To create a new version of a shapefile in a different coordinate system, you can specify that coordinate system for the data frame and then Export the shapefile using the same coordinate system as the data frame.  ArcTools also contains formal data projection/reprojection modules.