Company I work for in Canada does use a surveyor for stockpile measurements. A few years back they began using a company called Stockpile Reports and used their cell phones to take walk-around pictures of their stockpiles. The pictures were used by Stockpile Reports to give a quantity of the piles. They have now gone airborn with a
P4P to do the photo work and still use Stockpile Reports to process the images for quantity analysis. They have checked the piles flown with a surveyor and find the variance in amounts to be negligible. They believe that the
P4P photos have better accuracy as the ground survey depends on interpolation between recorded shots which means take lots and lots of shots. They are currently trying to incorporate the
P4P into other aspects of survey such as Original Ground pick-up etc. As far as their using Stockpile Reports they find that it is a third party entity that gives more legitimacy to the results.