A common way to create new features is to trace their shapes on screen using another layer for reference. This technique is called heads-up digitizing, or sometimes screen digitizing. When you digitize a feature, each time you click a location on the screen, an x,y coordinate pair is recorded and stored as part of the feature shape.
The layer used for reference during heads-up digitizing is called the base layer. Scanned paper maps, digital aerial photos, and other GIS layers are typically used as base layers.
To digitize a feature, you follow the steps below:
- Start an edit session and set your editing environment (target layer and task).
- Zoom to the feature you want to digitize on your base layer.
- Create the feature's sketch by tracing the outline of the feature, clicking to create each vertex.
- Save your edits, which saves the sketch as a new feature.