On-Site Magazine

Data collection in the fast lane

By Jacob Stoller   

Construction

Hardware and software advances are behind massive improvements, and significant expansion, in drone surveying in construction.

(Photo courtesy of PCL Construction)

Technologies often really take off when simultaneous developments combine. In construction, developments in drone hardware and BIM/VDC modelling software are fuelling significant expansion of construction use cases.

“We’ve seen huge advances on both the drone side and the VDC/ BIM modelling side,” says Amir Jalali Afshar, integrated construction technology specialist at PCL Construction, and a Transport Canada certified drone pilot. “So, if we can combine those two forces, we can get a lot more value out of drone data.”

Advances in cameras and sensors, the drones that carry them, and the software that manages the data are all contributing to this synergy. The latest drones are faster, more versatile and can carry bigger payloads.

“One thing that’s improved is that some of these drones can carry two payloads,” says Brad North, manager of integrated construction technology at PCL (Saskatoon). “So, you could have a thermal camera plus a zoom lens on some of these drones. You can also have interchangeable lenses, so you could get, for example, close-ups of a bridge without losing quality from digital zoom.”

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Drones have become a lot safer as well, allowing them to gather data at close range. “We’re working with drones that have what’s called omni-directional obstacle avoidance,” says North. “It has sensors around the entire drone to make sure it’s not going to hit anything. So, we can use them for scanning a building or a bridge because they’re so much safer.”

Emergency parachutes are another drone feature that’s becoming more common, North notes. Drones so equipped can fly safely and legally over areas where people are present.

More drones are also able to carry LiDAR scanners, which improves ground surveys.

“If you fly a greenfield site in Saskatchewan, there might be vegetation or tall grass on the surface,” says North. “With a regular camera, any vegetation is going to give you an inaccurate image of the ground, so you’d have to clean that up in the model. But with LiDAR, you actually penetrate that and get an accurate image of the surface. So again, additional and different payloads on drones are helping us strive for increased accuracy.”

One of the keys to better ground surveys is Real-Time Kinematic (RTK) technology, which adjusts the data from drones by using base station coordinates to create surveys that are far more accurate than conventional GPS. “With coverage from only a few checkpoints on the ground,” says Afshar, “RTK information allows us to bring that drone data to exactly where our model is, with an accuracy of less than two inches.”

Longer battery life and shutter technology are also impacting the power and efficiency of drones. Not having to change batteries mid-flight reduces downtime, and faster shutters in the cameras enable surveys of large areas to be done in a fraction of the time.

“A mission that used to take us 25 minutes with a couple of battery changes now takes four minutes,” says North. “If you had to map 100 acres with a previous drone, that might have taken two to three hours. Now, that mission would take literally 20 minutes.”

 

GROWING DEMAND FROM THE FIELD

Use cases for drone surveys are expanding throughout the construction cycle.

“I’d say that in the past few years, we’ve seen a tenfold increase in demand,” says Neil Chauhan, director of VDC services at EllisDon. “In pre-construction, it might be for mapping out an area for pursuit or estimating. During construction itself, it could be for in-progress tracking of the project, stockpile analysis, or just to provide data-rich and accurate 3D models in general. Then post construction, it could be used to showcase a project.”

Chauhan believes improvements in technology will lead to further growth. “I would say the software for processing this data that’s captured in the field by a drone is continuing to accelerate in its development,” he says. “So, we’re going to see a lot of new and exciting use cases for drone technologies.”

Mandates for virtual models on major projects will further accelerate the trend.

“We’re pushing for mandates in terms of BIM and VDC adoption, and I see drone surveys going along with that,” says Chauhan.

 

Jacob Stoller

Jacob Stoller is principal of StollerStrategies. Send comments to editor@on-sitemag.com.

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