FREC 480 -- ArcMap Quick and Dirty

Getting oriented

The easiest way to learn ArcMap is to play with it and experiment with its capabilities.  Check out the menu options and tools; see what left and right mouse-clicks bring up. Since ArcMap uses a lot of system resources, do not run more than one ArcMap session at a time. 

When you launch a new ArcMap session you get a blank window with legend on the left and map frame on the right. 
When you add a geodatabase or individual data layers to a data frame, they are listed in the Table of Contents and (unless you uncheck them) displayed in the map frame. 

arcmap window

As shown here, you will usually see the "standard" and "tools" toolbars below the menu. If you mouse-over the icons you will see their names. You can access many other specialized toolbars via Customize-Toolbars or 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 or as a frame that you can pin in the main window.  It lets you manage your geodata files and access the ArcTools menu as well. If you check an individual shapefile or raster with MS-Explorer, you will see that it is actually many files; do not mess with these component files! ArcCatalog lets you copy, move or rename geodata files safely. Multiple geodata layers can be combined and managed in a single Personal Geodatabase file, basically an MS-Access-format database.



ArcTools is a large customizable library of specialized GIS modules.  Beyond that, there are additional functions that you can run at the Python window which has replaced the old ArcINFO-style command line.


Many commonly-used functions are available in the basic menu:

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: copy map to clipboard (can paste into Adobe Photoshop or Paint).  ArcMap's un-do capability is limited.
View: Switch between Data and Layout views (same as little tabs at the bottom left corner of the map frame); create charts or reports; access dataframe Properties (same as right-clicking on the dataframe in the Table of Contents).
Bookmarks: create a particular zoom area of your map and re-zoom your map to it.
Insert: 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. 
Geoprocessing: buffer, clip, intersect, merge, union, dissolve and other feature manipulation tools.
Customize: access toolbars; activate extensions such as Spatial Analyst (for raster data) or 3D Analyst (for TIN's and 3D viewing).
Windows: activates separate map overview (full extent) and/or magnifier (zoom) windows; restores your Table of Contents frame if you accidentally close it.
Help (or use F1 key): Contents tab provides informatoin hierarchically by topic, or use the Index tab to research a specific utility or term.


An ArcMap session uses multiple map layers in a single dataframe. The default name of the dataframe is "Layers" (at the top of the Table of Contents). Right-click on "Layers" in the Table of Contents to access the tabbed Data Frame Properties window in which you can set the coordinate system and other properties of the entire dataframe.


Right-click on any individual layer's name in the Table of Contents to access a tabbed Layer Properties window in which you can set the Symbology, layer transparency level, label formats, method of displaying selected features, etc.



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.  Unless it is embedded into a geodatabase, 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." 

Each shapefile has an associated attribute table that contains one record (row) for each individual geographic feature in the shapefile. The attribute table typically contains multiple attribute data fields (columns) describing the features.

Each raster has an attribute table that contains one record for each raster category value.  (All the raster cells in a particular attribute category are treated 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. 


One of the really useful things about ArcMap is that you can join an external table such as an Excel spreadsheet to a layer's attribute table, based on matching fields in the two tables.  This makes it easy to create thematic maps from external data.   You will be doing this in the first project.

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 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
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 some shapefile features are selected...
  • When you export shapefile features or attribute records to a new file, only the selected elements will be be exported.
  • When you calculate summary statistics on an attribute field, the statistics are only calculated for the selected features.
  • When you use the shapefile features as targets for Spatial Analyst's Distance module, only the selected features will be used as targets.
So it is good practice to "Clear Selected Features" when you no longer need them selected. 

A note on projections and coordinate systems.

You will be required specify an appropriate coordinate system (via the data frame Properties tab) for every map image that you include in your submitted projects.  Do not submit unprojected maps!   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 data frame.  But be careful about calculating distance or area measures based on unprojected features, even if they are displayed in a projected coordinate system.

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 ArcMap. 

To create a new version of a shapefile in the coordinate system of the dataframe, use Data--Export Data to create a copy of the shapefile in the data frame's coordinate system. .  (This is often quicker than using Arc's formal reprojection modules.)