INTERGEO 2015: senseFly eXom Drone Capable of Millimeter Accuracy

September 15, 2015  - By

senseFly has published a white paper named “Generating highly accurate 3D data using a senseFly eXom drone” which presents the results of two photogrammetric land surveys of a construction site. The project was completed earlier in September using two senseFly eXom close mapping and inspection drones, and the announcement was made during INTERGEO, held Sept. 15–17 in Stuttgart, Germany.

Figure 8 - Check point results for flight 1, taken from Postflight Terra 3D's Quality ReportThe results demonstrate that 3D point clouds produced with an eXom quadcopter can reach a global precision comparable to that of a total station survey and meet the typical accuracy requirements of construction projects, according to a news release from senseFly.

The first eXom survey (figure 8) achieved 2.1 millimeter accuracy in X, 1.9 millimeter in Y and 0.1 millimeter in Z (RMSE). The second eXom survey (figure 9) achieved 0.8 millimeter (X), 0.5 millimeter (Y) and 4.2 millimeter (Z).

“This degree of absolute accuracy from a drone is unparalleled and positions the eXom as a surveying instrument that is comparable in performance to standard total stations,” said Andrea Halter, senseFly’s co-founder. “These results were due, in part, to the high 38 MP resolution and sharpness of the flight’s images, captured by the main camera inside eXom’s TripleView head. Add to this image quality the ability to operate close to the terrain and the introduction of highly precise ground controls and you have a recipe for exceptionally accurate 3D data.”

Figure 9 - check point results for flight 2, taken from Postflight Terra 3D's Quality ReportTwo eXom drones flew separate survey missions at an altitude of 14 meters above the site, achieving an average ground sampling distance (GSD) of 2.2 millimeters, senseFly says. All the flights were completed using the drone’s Interactive ScreenFly flight mode, whereby the UAV (unmanned aerial vehicle) is controlled using a handheld ScreenFly controller connected to senseFly’s eMotion X flight planning and control software.

This flight mode’s “cruise control” feature, combined with its auto-trigger function, enabled each of the eXom drones to survey the 1,100-square-meter site in a single flight. Meanwhile, the live on-screen feedback from the drone’s five different navcams and ultrasonic proximity sensors helped the operator ensure that no contact was made with either the on-site crane or any the trees surrounding the complex site, senseFly says.

“This project’s flights took place at 14 meters above the ground, but with the eXom’s Distance Lock feature we are able to safely fly just 4 meters away, so it isn’t unrealistic to think that the accuracy we achieved could be improved still further.”

To download the eXom accuracy white paper click here.

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About the Author: Joelle Harms

Joelle Harms is the digital media manager for GPS World. Harms completed her undergraduate degree at Ohio University where she earned a Bachelor of Science in Journalism and creative writing specialization from the E.W. Scripps School of Journalism. She specifically creates content for GPS World and Geospatial Solutions digital properties including newsletters, videos, social media and websites.