Select this option on the Settings tab if you want AutoGEM to modify or delete existing elements as required. AutoGEM does not modify or delete existing wedge or brick solids.

AutoGEM sometimes cannot create a full set of elements on a surface or volume having complex features. If you select Modify or Delete Existing Elements, AutoGEM is more likely to fully cover each surface or volume with elements.

In general, you should select Modify or Delete Existing Elements. If you want to keep any existing elements, you should deselect this check button.