3.2 Create Exclusion Zones
Level of expertise required for this Chapter: Intermediate; general Map Maker training
There are three alternative approaches to create an ‘exclusion zone’, i.e. an area within another area (internal polygon surrounded by an external polygon, or ‘island’).
A) You first digitize the internal polygon, then the external. Use the Subtract island command (see Chapter 2.15 for the procedure to define larger unit surrounding islands).
B) You first digitize the external polygon, then the internal. Use the Cutter-tool (toolbar left) from within the larger unit (see Chapter 2.14 for the procedure to insert an island).
C) You digitize in any sequence and use the Intersect option to extract them from each other.
Main menu > Utilities > Vector utilities > Intersect / Unite files > Intersect lines and polygons window: Add file > Select folder > Select file (only one) > Open > Tick ‘Find intersections’ > Tick ‘Tidy boundaries’ > Execute > Save result as > Select folder > Give new temporary filename > Save > Quit
See Chapter 7.5.3 for integration of exclusion zones in the Structure Plan.