I am looking to gather all model elements that have been placed in a project. In working through this, I used a FilteredElementCollector to filter all walls, and then delete them. This resulted with *ALL* walls being deleted, even the unplaced wall families in the Project Browser. I then checked to see is the wall was on a level. This worked for walls, and some other element types, such as floors and ceilings, but a lot of other types are showing that they aren't on a level. So this method won't work. Is there a sure fire method to filter to placed elements in the Revit file? Am I overlooking something. I tried searching through the API.chm, but unfortunately couldn't find what I am after.
Thanks