Cannot Process Multiple Boundaries Because the Outer Polyline Includes Loops (Using the Multiple Option with a Hatch)

Issue

You saw the following error message when attempting to exclude internal areas from a hatch using the Multiple option:

Cannot process multiple boundaries because the outer polyline includes loops.

Try redrawing the polyline boundary without loops or self intersections.

Would you like to see more information?

You might be seeing this error when attempting to exclude internal objects from a planting (groundcover), site, hardscape, or irrigation hatch.

Cause

The outer boundary of the hatched area includes one or more loops or self intersections, which can easily be added accidentally to hastily drawing polylines. The Multiple option for excluding internal objects from hatches works by converting this outer polyline boundary of the hatched area into a Region.

If the outer boundary does include loops, it cannot be converted into a Region, and the Multiple option will fail as a result, which will in turn apply the hatch to the internal objects you wanted to exclude.

Solution

For the Multiple option to work correctly, you'll need to redraw the polyline boundary of the hatched area so it doesn't include loops.

Note that loops in polyline boundaries can be difficult to detect. You'll often need to zoom in to see them, as in the example to the left.

 

After locating the loop in the hatch boundary, you can either move the vertices to remove the loop or completely redraw the polyline so it doesn't include the loop(s).

 

Once you've removed the loop(s), the Multiple option should work correctly and exclude the internal objects from the hatch without generating the error.