One of the least fun freelance jobs I ever did was helping an interior designer measure out a recently-shuttered dot-com office. The space was massive, and while the designer had the original blueprints, the real deal didn't quite jive; there were surprise soffets, new partition walls and of course nothing was square. It took a day and a half using our tape measures and a laser and we still hadn't gotten it quite right.
Augmented Reality Measuring Apps for Designers