The information in this article applies to:
In X5 and above, I should be able to see the floor below in stairwells and other open below room areas in a floor overview, but mine has somehow been turned off. How do I turn it back on?
A new feature introduced in X5 was the ability to see lower floors in floor overviews. This feature makes it possible to see down the stairs or over a railing, gazing into the room below. Since this is a new feature in X5, plans brought forward from an earlier version will not have this enabled by default.
When checked, the current floor plus any floors beneath it are included in the view. Since the program is generating multiple floors it may slow down the render unsatisfactorily. If it becomes problematic, it may be more efficient to only enable this feature in the Floor Overview Camera Specification dialog of the individual camera.