|Job Type||Stockpile volume calculation|
|Project Date||February 2017|
|Project Size||3.3 acres (13,200 sqm)|
|Drone||Phantom 4 Pro|
|Flight Altitude||132 ft. (40 m)|
|Accuracy||2.5% volume difference without GCPs|
|Number of Images Required||45|
|DatuSurvey Field Savings||30 min of field work instead of 1.5 hours, no need to climb the pile|
|DatuSurvey Office Savings||1 office hour instead of 1 office day|
High precision stockpile volume calculation was required to be accomplished in a short time, without using Ground Control Points in a safe and automated process. The area was surveyed with DJI Phantom 4 Pro with the use of DatuFly™ drone app. The received images were later on processed with DatuSurvey™ Enterprise. This case study describes the outputs received with DatuSurvey™ Enterprise Softwar and compares them to the results achieved with the traditional surveying method. In the end, we describe the object elimination processing.
Data was collected with a DJI Phantom 4 Pro drone using a 20 MP camera. Mission was planned with flight planner app DatuFly™ , allowing quick, precise and automatic image capturing. Flight duration was 6 minutes at an altitude of 132 ft. (40m). Resolution was 2.4cm/pixel.
Four Ground Control Points in the area of the project were surveyed by RTK GPS. The first project of stockpile volume calculation was geo-referenced with the GeoTag option utilizing only the GPS data embedded in the EXIF of the image. The second project of stockpile volume calculation was geo-referenced using Ground Control Points.
The area of the stockpile was surveyed by using the conventional method with RTK GPS. The data includes 173 points describing the surface of the pile. This data was used for comparison.
Achieved ResultsThe project was processed in less than an hour, including dense point cloud with mesh and texture and volume calculation reports. The difference between stockpile volume without GCP and with GCP was 2.5%. The difference between volume with the conventional method and volume without GCP wass 4.5%, while there were 8,566 points describing the surface compared to 173 points of conventional survey. Scale accuracy could also be checked by measuring the distance between the car wheels. The distance measured in the project without Ground Control Points differed from the actual size by 2 cm (0.06 ft.) The distance measured in the project with Ground Control Points differed from the actual size by 0.66 cm (0.002 ft.).
DatuSurvey Enterprise Outputs
Texturized Dense Point Cloud
Stockpile Volume Calculation – Dense Point Cloud with Surface
Surface for Stockpile Volume Calculation
Conventional Topo Survey
Surface from DatuSurvey™ via Imported Conventional Topo Survey
DatuSurvey Volume Report
An additional project was made with a car on the top of the pile. In order to eliminate the car from the volume calculation it’s simply not included in the polygon of interest.