Hi Lee,
The PM function is typically for box shaped buildings. In our historic downtown area, we hardly have a building with a rectangular plan so I cannot even use PM for those - not to speak about organic shapes like valleys and rocks. I doubt that it could ever be successfully used for those.
There are other techniques/applications but generally they involve more photos taken from different angles so that the software (like TGi3D PhotoScan) can create the 3D shape from those different shots. Just like our two eyes that see two, different images of the same object and our brain puts those together into a 3D image (or something)