Stockpile Volume Calculation without Ground Control Points

Job Type Stockpile volume calculation
CountryKentucky, USA
Project Date February 2017
Project Size3.3 acres (13,200 sqm)
Drone Phantom 4 Pro
Flight PatternOblique
Flight Altitude132 ft. (40 m)
Resolution2.4 cm/px
Accuracy2.5% volume difference without GCPs
Number of Images Required45
DatuSurvey Field Savings30 min of field work instead of 1.5 hours, no need to climb the pile
DatuSurvey Office Savings1 office hour instead of 1 office day

Project Description

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 Acquisition

 Images

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.

Stockpile Volume Calculation Drone Photoshooting Datumate.PNG

Geo-Referencing

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.

Conventional Survey

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 Results

The 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.

 

Stockpile Volume Calculation Accuracy Validation Datumate

 

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 Datumate

 

 

Stockpile Volume Calculation – Dense Point Cloud with Surface

Stockpile Volume Calculation Dense Point Cloud with Surface Datumate

 

Surface for Stockpile Volume Calculation

Stockpile Volume Calculation Surface Datumate

 

Conventional  Topo Survey

Stockpile Volume Calculation Convetional Topo Survey Datumate

 

Surface from DatuSurveyvia Imported Conventional Topo Survey

Stockpile Volume Calculation Convetional Topo Survey vs imported topo survey Datumate
Yellow TIN – DatuSurvey surface; Green TIN – conventional survey surface

 

True Orthophoto

Stockpile Volume Calculation True Orthophoto Datumate

 

 

 

DatuSurvey Volume Report

Stockpile Volume Calculation Report Datumate

Object Elimination

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.

Texturized Dense Point Cloud with a Car on Top

Stockpile Volume Calculation Texturized densepoint cloud Datumate

 

Surface for Stockpile Volume Calculation

Stockpile Volume Calculation Surface Datumate 2