ARCHIVED: Basics of digitizing in ArcGIS

This document presents simple instructions for digitizing features in ArcMap. The examples in this document assume the existence of a background raster data set (named source) which depicts features to be digitized, and a new Geodatabase/Feature Class (named forest) in which the new digitized features will be created.

Important: Save your edits frequently during your edit session. To do so, from the Editor toolbar, select Editor, and then Save Edits.

Note: Selecting File and then Save from the main ArcMap menu does not save your edits; rather, it saves the settings only in your current work session (i.e., the list of features in your Table Of Contents and Data Frame, the symbols you've used to draw them, and the extent to which you are zoomed). Saving the session in this way helps save you time when you set the symbolization for a Data Frame that will have a lot of features, but does nothing to modify, save, or edit the data.

1. To add source and forest to your ArcMap session, begin with a new ArcMap session.
2. To turn on the Editor toolbar in ArcMap, from the View menu, select Toolbars, and then Editor. Note: If you cannot select the feature class you want to edit, you may be modifying it in ArcCatalog or in another session. Close all other Arc Modules (ArcCatalog) to see if you can then proceed.
3. To select the layer to which you wish to add features, on the Editor toolbar, set the "Target:" to forest.
4. Zoom to the feature to be digitized, and from the Editor toolbar, select the Sketch Tool (the pencil icon).
5. Choose from the following options to create and modify the new feature:
   • To create a polygon feature, left-click once in the Data Frame to start a new polygon. Successive single left-clicks will create vertices. Double-click at the last vertex to create a closed polygon.
   • If you are editing a point feature class, left-click to add a single point location.
   • If you are editing a line feature, left-click to start a new line and add vertices with successive single left-clicks. End the line with a double left-click.
   • If you are in the middle of editing a line and realize that you want to make a correction to a part of that line you have already completed, double-click to finish the line segment. Then select the Edit Tool (the black arrow just to the left of the pencil icon in the Editor toolbar). Use this tool to select a feature by double-clicking it, and move the vertices individually.
   • Use the Esc key to get out of a particular step if you get stuck in it.
   • The Undo option can be quite helpful. To use it, press Ctrl-z; alternatively, from the Edit menu, select Undo. If your polygon gets too complicated to fix, you can use the Edit Tool to select it, and then delete it by pressing the Del key.
   • For instructions on how to create island polygons, see ARCHIVED: In ArcGIS, how do I create an island polygon?
   
   
6. Repeat Step 5 as needed until all features are digitized.

   Note: You can pan and zoom while in the middle of digitizing a feature. Another handy feature is the magnifier window. To open this, from the main ArcMap menu bar, from the Window menu, select Magnifier.... This allows you to have a separate window zoomed into a portion of the main Data Frame. You can pan and zoom this window around your Data Frame, which is a convenient way to follow the path of a long feature.

7. Once you have digitized all the features, to save your edits, from the Editor toolbar, select Editor, and then Save Edits.
8. To stop editing, from the Editor toolbar, select Editor, and then Stop Editing.

For more information on editing in ArcGIS, see:

  http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=An_overview_of_editing_and_data_compilation