Colorado DOT

Job TypeTopography and structure survey project of water pond
ComapnyCDOT (Colorado Department of Transportation)
Country CO, USA
Project DateNov. 2016
Project Size9,307 m2 (2.3 acers)
Drone Phantom 3
Pattern of flightVertical
Number of Images33
Accuracybetter than 6cm (0.197 ft)
DatuSurvey savings1 field hour instead of 1 field day using RTK 1 office day instead of 1.5 using RTK

CODOT logo1

“Datumate has provided us with an important professional solution for expediting CDOT projects and supporting our mission to ensure a safe and efficient highway system in Colorado. We’re looking forward at utilizing this technology for additional jobs in congested and populated areas, highways, mountainous, steep or wet locations, rockslides etc.”

Kathryn Lyon, Central Unit Coordinator at CDOT. 

Project Description

CDOT  (Colorado Department of Transportation) needed to survey a water pond to ensure the safety of travelers on the nearby highway.  The purpose of the survey was to calculate the maximal volume of water that can fill the pond before overflow occurs.

A DJI Phantom 3 drone, managed by DatuFly™ professional surveying app, was used for easy and harmless photoshooting. The aerial photography was then processed using DatuSurveyTM Enterprise photogrammetry software.

Data Acquisition

Acquiring Images

The DatuFly app, together with a Phantom 3 drone allowed for quick, precise and easy image capturing.

The flight duration was 6 min, 23 sec at an altitude of 157 ft.

Inflight direction overlap was 75%.

In perpendicular flight direction overlap was 60%.

Resolution was 2.5 cm/pixel.

Flight speed was 2 m/s. At least 2-pixel accuracy was expected with the rolling shutter of the Phantom 3 camera.

CDOT DatuFly screen

Acquiring Ground Control Points

White plates with nails in the center were distributed in a grid pattern throughout the field.

The points were measured with RTK GPS.

9 points were used as Ground Control Points.

9 additional points were used as Check Points, to detect the accuracy of the project.

Control Points digitization precision was 2-3 pixels.

CDOT aquiring GCPs

CDOT Aquiring GCPs2

DatuSurvey Enterprise Outputs

The Drone’s imagery was analyzed and processed using DatuSurveyTM Enterprise photogrammetry software to quickly generate a dense point cloud, true Orthophoto images, water volume and maximal height calculations and more.

A point file, including names, codes, descriptions and coordinates of all new points was generated. Overall, more than 320 new points were drafted directly on the images.

The measurement accuracy of all the points was better than 6 cm (0.197ft) in 3d coordinates.

 

True Orthophoto

CDOT True Orthophoto

Generation time: 24 min

Dense Point Cloud

CDOT Dense Point Cloud

Generation time: 8 min

Cad Data

CDOT CAD DATA

 

Achieved Results

A 3D CAD model in DXF format was created. It included the area topography, concrete structures and additional objects that were generated by drafting directly on the images using DatuSurveyTM.

Finalized Topographic CAD Map

The map in 1:40 scale was generated in AutoCAD Civil 3D.

CDOT Topographic CAD Map

Orthophoto with CAD Data

CDOT Orthophoto with CAD Data

Volume Calculation

One of the main goals of the project was to calculate the volume of water needed to fill the pond before overflow occurs.

The height of this point was extracted from the DatuSurveyTM measurements and the surface was established at 5391.6 ft.

DatuSurveyTM calculated the volume of the pond, from pond floor to the surface.

CDOT Volume calculation

CDOT Volume calculation Report