Animation problem

[Devin Johnston]

I'm doing a motion tracked animation of a large site, there are two existing buildings on the site that my model is surrounding. In order to cut out the existing buildings I'm using a rough geometric object with a matte shadow material applied. This works great and I woulden't have a problem except for the fact that I'm developing this model from a single PDF site plan and the scale and location of it is questionable and as a result the building isn't being cut out properly. I'm looking for a way to get around this, is it possible to somehow map or project the image of the building from my background video onto the rough geometric object I've created?