Graniet Import Benelux from Amsterdam commisioned Skeye to carry out an aerial survey to determine the accuracy of volume calculations on their stockpile. The Eagle-Eye UAS was used for this survey. Photographs were made at an altitude of 50 meters above the highest peak of the mounts of earth and granite. On the ground a number of ground control points were measured in order to geo-reference the imagery. From the overlap in the imagery a digital terrain model was generated with a point density of more than 30 points per square meter. 40 control points were also measured using a GPS in order to check the accuracy of the aerial survey. The result showed that the average error was no more than 32 mm with a standard deviation of 19mm. The high density of heights derived from the photography shows every undulation on the mounts. These undulations are of course very important for volume calculations but cannot be taken into account during traditional surveys by hand(GPS).