As many parents have learned in the last couple of years, the fastest way to a tween’s heart is to give him the freedom of flight, packaged in a cardboard box from Amazon. Cheap, mass-produced drones are always a welcome kid gift, but the higher-tech versions of this burgeoning technology are much more than just a “hot toy.” Advanced drones have given countless industries – from gaming to moviemaking to real estate – a fresh perspective on the world. And for the construction industry, the possibilities are as limitless as a clear blue sky.
Construction firms are using drones to capture aerial footage of existing building conditions, and to accurately document the contours of undeveloped land. They’re feeding three-dimensional data maps into software to form a basis for 3-D construction models, quickly catching errors and translating construction drawings into constructed buildings. They’re sending robotic cameras into dangerous areas, instead of human beings.
These construction pioneers are making known the previously unknown by using drones for mapping and modeling, documentation and inspections, and engaging clients.
Mapping and Modeling
In construction modeling, teams want good-quality data fast and at a low cost. With ground scanning, they might get one or two of these three. With a drone, they get it all. “With drones, the speed of capture is quick, the quality is very accurate and the quality of information is fantastic,” says Grant Hagen, virtual design and construction manager with The Beck Group.
Drone operators can pre-program a route for a flight over a construction site, and on one battery charge and 15 minutes in the air, it will capture images every few seconds, automatically assign them to a GPS-based grid. The only physical labor involved is painting a big X on the ground to give the drone a ground-control reference point that increases accuracy and keeps objects in scale.
Back at the office, the images can be exported into processing software that automatically creates a 3-D map and model in a process known as photogrammetry. The software uses an algorithm to stitch all the photos together, matching up pixels based on the GPS position of the drone and triangulating each in space to make a three-dimensional “point cloud.” This forms the foundation of a computerized 3-D landscape, allowing the preconstruction team to conceptualize how the building will sit on the actual contours of the land.
The drone-capture and mapping process enhances the existing workflow by capturing more information more quickly and efficiently. Traditional ground scanning requires about 20 scans, which take about 10 minutes each before the scanner has to be physically moved to a new location and set up again. Once the ground scans are complete, technicians use a time-consuming process to match up the scan points, connect them all together and create one concise model.
A drone can achieve the same level of quality as a laser ground scanner costing six figures, but with just a four- to five-figure price tag. A drone scan also shows much more detail than a ground scan, as the ground scan is limited to a point of view that’s ground-level.
Hagen says that The Beck Group finds many uses for drone scans, including overlaying engineering, architectural and utility plans onto aerial site photos, allowing for more accurate modeling and estimating much earlier in the preconstruction process. Drone scans also form the foundation for realistic 3-D modeling during the conception phase.
“When we align a point cloud up on a surveyor-created CAD file, it lines up exactly,” he says. “We have two different, independent workflows, but when we overlay them, they are scaled exactly on top of each other.”
Documentation and Inspections
In addition to using drone scans as a foundation for renderings of proposed buildings, they can take the place of people for inspections and documentation.
“There are safety aspects to sending people up on boom or lift,” Hagen says. “It’s easier to fly a device and not have a human at risk. In fact, we got into this technology because of a five-story cluster of buildings where we were trying to inspect the shingles. We decided that we needed to replace the whole idea of getting a man on a lift with a camera. Since then, our primary motive with this technology has been to decrease risk and increase quality in construction.”
Repeat scans can be used to track changes and progress on the construction site as a building goes up, comparing current work to design models as well as the work that was completed a week ago. Compared with a 4-D model with an embedded schedule, a drone scan can indicate if construction is happening at the expected rate, so course corrections can be made to keep the project on track.
Some advanced aerial devices can do thermal imaging studies to compare heat loss variation between different roofing materials. They also can be used to document earthwork, regularly surveying and measuring stockpiles to accurately calculate volumes of dirt that come and go over days and weeks.
Maps and models created from the air also can provide valuable information about what’s going on underground. Used at the right time, drone scans can document where underground utilities are about to buried, or where high-tension cables will soon be concealed inside a building’s foundation. Creating a visual record during construction is much cheaper and easier than x-raying to locate hidden dangers after construction is complete.
Plenty of third-party companies are happy to run drone flights on behalf of construction firms. But what’s holding construction companies back from adding drones to their VDC capabilities?
There’s no longer a pilot license required, although the FAA does require a drone-licensing exam and may require approval for flights in certain areas, such as near airports. Some construction firms are intimidated by the highly specialized knowledge needed to break new ground with a rapidly changing, new technology. Others worry about the legal parameters and risk.
Whether they run drones in-house or outsource the service, more and more construction firms are coming around to the idea that this is a useful technology that will bring enhancements to existing workflows. But to project owners who have a lot of money on the line, is a drone just a nifty toy, or does it have a real impact on who wins the work?
As the saying goes, “A picture is worth a thousand words.” Owners are, by nature, emotionally invested in their projects. They have vision, time and money on the line. Gone are the days when they were delighted if they could get four or five different helicopter photos of the job site each month.
If you really want to ramp up an owner’s excitement, show them your drone footage at your first concept meeting. Or better yet, show them the 3-D model you built of their idea, overlaid on top of your drone footage, with a 360-degree panoramic view and embedded pricing. Zoom in, zoom out. Pause, back up and take in all the detail. See what the view will be from the 26th floor of a building that isn’t built yet.
“Emotional engagement comes from being able to see their project from different perspectives,” Hagen says. “Drones allow preconstruction to understand the site before they even get there, and gives architects a background of what the land looks like, so together, they can show the client what the build will look like in relationship to the land. It’s about trying to better portray to prospective clients the building they will occupy in the future.”