QuestUAV's gimballed sensor improves UAS 3D mapping

By Patrick C. Miller | January 19, 2017

QuestUAV Ltd. has developed a gimballed system that it says is 15 percent more efficient in capturing images for 3D models of areas surveyed with unmanned aircraft systems (UAS).

Based in Northumberland, England, the company’s system is designed to compensate for the effects of wind and turbulence that often lead to blurred images and low image overlap. According to QuestUAV, its latest gimballed system is fine-tuned to gain maximum quality and performance from a flight mission.

To map an area, a drone flies and photographs a grid pattern to ensure that features on the ground are visible in multiple photographs. To generate 3D models, the photos require sufficient overlap in flight direction and between grid lines—side overlap.

Photogrammetry software providers such as Pix4D or Agisoft Photoscan generally recommend an overlap of 75 percent frontal and 60 percent side overlap, the company said. The sensor determines what data a UAS is capable of collecting. Ground sampling distance (GSD), image sharpness and noise level are all dependent on the sensor chosen for a flight mission.

The QuestUAV 200 Surveyor carries a Sony A6000 camera which captures very high detail with a 24.3 effective megapixel APS-C sensor allowing it to acquire data down to 2.9 cm GSD at 400 feet. According to QuestUAV, its Exmor APS HD CMOS sensor provides fast performance, sharp image quality and low noise images in low-light conditions.

QuestUAV said the advantage of a gimbal is that it enables the sensor to continuously point directly towards the ground while the aircraft maneuvering around in yaw, pitch and roll.

Studies with a QuestUAV 200 Surveyor and QuestUAV 100 DATAhawk have demonstrated that a gimballed system allows reducing the image overlap from 65 to 40 percent while guaranteeing enough overlap for photogrammetric processing and data quality even in high winds.

By reducing the amount of grid lines and aircraft turns, the ground coverage of a QuestUAV system is further increased. The number of grid lines are reduced from 13 to 10 and the total path length from 10.1 km to 8.3km—a decrease of 18 percent.