Tipster James J. Olszewski sent this trick to avoid internal closed areas when hatching in AutoCAD. “This tip concerns the frustrating scenario of choosing a location to be hatched that ends up going beyond the bordered area covering an internal object.
“I recently was hatching a bordered area that had an enclosed polyline inside it. I clearly did not want to hatch the internal area, but as often is the case, it covered that area anyway. I checked that it was a closed polyline and tried again with the same result. Finally, after trying a third time, when asked to pick a point after the area was covered over, I picked inside the polyline before completing the hatch, and AutoCAD removed the hatching within the polyline. (I seem to recall earlier versions having an remove option, though I may be mistaken.) It's a new trick for this old dog.”
Notes from Cadalyst tip reviewer Brian Benton: AutoCAD has three settings for what is called island detection, which is what we have in this example. Start your hatch and go to its settings. Turn on island detection and pick one of these settings:
- Normal will hatch inward when you specify the internal pick point; islands remain unhatched and islands within islands are hatched.
- Outer will hatch inward but ignore islands and islands within islands. Outer is the setting recommended by Autodesk.
- Ignore will hatch the entire selected object, including all islands.
If you have hatched an area and want to remove a section of it, use the Trim command and trim away the internal section. You can always draw an area to be removed and trim it. But picking the internal areas to be hatch/not hatched while creating the hatch will define the filled areas ahead of time.