MI Digitising Common Boundary

Method

When digitising polygons (regions) with common boundaries, to easily pick up the boundary of an existing polygon, use the Ctrl and Shift keys whilst Snap is on (toggle the S key to turn snapping on and off). When digitising, after snapping to the existing polygon, move the cursor further along the existing polygon’s perimeter and hold the cursor over a vertice (node) so the Snap cross-hairs appear. Hold the Shift key down to pick up all of the vertices between the last digitised point and the cursor. Hold the Ctrl key down to pick up all of the vertices in the other direction (you can see which sides of the existing polygon are picked up on the screen). Decide whether the Shift or Ctrl direction is the one required, and click the left mouse button to digitise all the intermediate vertices in one click.
Effective use of this feature can save a lot of time!