Revit: Disclaimer: Overrides may actually not override in some situations.

Due to Revit's limited functionality regarding bitmap images (there are no decent transparency options for one), I often have to resort to some trickery to get my bitmaps showing properly.

In this instance I had modeled an existing building roughly and wanted to display the original hand-drawn floor plan overlaid on the mass model. I had to place the bitmap drawing on the background of my plan view so that its white background wouldn't obstruct my Revit-modeled floor plan (here's where some more advanced transparency settings would go a long way). Since the mass model now obstructed the drawing, I figured I could simply override the mass model's display settings to show only edges. Luckily overriding display settings such as transparency is made simple in Revit!

The setting worked nicely, and I now had the plan drawing showing right through the mass model.

 On the sheet view all looked good still...

 ...but the Print Preview window showed the ugly truth. The transparency override actually doesn't print at all, at least not in this particular case.

In another project I had successfully overridden the transparency of some objects, but it was a 3D camera view, not an orthographic projection. Maybe transparency just can't work in plan or elevation views, for reasons yet undisclosed?