Drones for Surveying

Measuring Dirt with Drone LiDAR

Adams Surveying Hits Paydirt by using drone LiDAR to perform dirt verification.

Everything might be bigger in Texas, but a skilled pilot operating a fully integrated LiDAR system from Microdrones can make the work of producing detailed ground surveys of big properties go a lot quicker. Adams Surveying, LLC, of Richardson, Texas, recently took on two large-acre jobs using the mdLiDAR1000HR to produce a pre-development site survey and a report on dirt levels and heights for an ongoing construction project.

These two projects with Graham Associates, an engineering and planning company, involved a survey of the approximately 800-acre Spradley Farms site and offered engineers and planners data on the property, which had not yet begun construction. As is often the case with pre-development sites, a thick canopy and grass necessitated the use of the LiDAR-equipped drone.

The mdLiDAR1000HR scans the property at Spradley Farms, in Texas

“The way Microdrones products help us at Adams Surveying in meeting our goals is when we come across an open field like this where photogrammetry is not going to be able to cut through the canopy or the grass,” said Adam Gribben, an sUAS Pilot and Survey tech in Piloting and Deployment Operations at Adams, which offers surveying services, construction taking, and topography and boundary work. “That’s where the LiDAR gets pulled in. There may be other circumstances where we use it, but most of the time it’s when we need to cut through some grass or cut through some canopy to get the ground level.”

In addition to the existing growth, a persistent wind on flight day offered an additional challenge for the Adams crew. Gribben used mdCockpit – part of the fully integrated Microdrones system – to develop preliminary flight patterns. Then he altered his flight pattern to a slightly less efficient approach to ensure that the drone would be flying safely with the wind – and to conserve battery power on the flight.

The mdLiDAR1000HR, part of the GE industrial drone line, is often used in land surveying, as well as in construction, oil and gas applications, and mining. It has a 90-degree field of view for both scanned points and imagery, and repeatedly provides a precision of 1.6 cm (.052 ft) at 1-σ when flown at 40 m (130 ft) at a speed of 8 m/s (18 mph).

“Performance I was very happy with. We’re still doing something that would have taken us two months and two weeks without the drone,” Gribben said. “So, we got it down, collected what we needed. And now we throw this through mdInfinity for processing and we can probably have our preliminary surface done today. I’m a very happy camper.”

Josh Adams, SIT and sUAS Pilot and Adam Gribben, an sUAS Pilot and Survey tech, prepare to start the drone survey project.

Site in Progress – A Different Set of Challenges

Adams’ second job for Graham Associates was to provide an updated survey of dirt levels and other features at the 900-acre Karis community development project in Crowley, Texas. This job presented a host of different challenges – including existing cell towers, highways, and the need for FAA LAANC flight approval – due to its location and the fact that it was already under construction.

Using Aloft, Gribben started the process by mapping the flight pattern with mdCockpit and seeking LAANC approval for the flight, which came nearly instantaneously. LiDAR flights occur at lower altitudes than photogrammetry alone, so careful flight planning is essential.

The goal of the survey was to verify dirt levels and heights at an essential stage of the project – after dirt had been moved but before individual site development had begun.

“This is a 2,100-home development with eight phases,” said Rachel Coward, assistant project manager with The Nehemiah Company. “We partnered with the city to bring this together. It is an exciting master plan community with a trail system, amenities, and parks. Our land planning is really, really important to the overall design feel of the communities.”

And to ensure accuracy, Adams did some small-scale ground truth work during the drone flight.

“We’re going to take some shots at various points with the idea that we can either prove or disprove the model that we make to make sure that our data is as accurate as possible,” said Josh Adams, SIT and sUAS Pilot at Adams. “The mdLiDAR1000HR is a great tool to use. It gives very high point density, so we can get a really good idea of what the average elevation is across the paths, across the lots, across the road. That way we get the most accurate depiction of what the dirt is.”

That accuracy, without the inherent risk and time-consuming nature of boots-on-the-ground surveying, is the foundation of Microdrones’ advantage.

“Using Microdrones provides us with tools that we don’t have in our toolbox otherwise,” said Philip Adams, RPLA, President and CEO of Adams Surveying. “Surveying is time- and labor-intensive, and there’s some hazards and dangers to it. Deploying a Microdrones drone over the site really provides us a quick and accurate picture of what’s going on. Then, using the tools available to us, we can assure survey-grade accuracy with the data we’re providing to the client.”

The mdLiDAR1000HR collects LiDAR data for verifying dirt levels at the Karis community development project in Crowley, Texas.

Putting it All Together

All of the visually impressive drone flights mean nothing if they can’t be translated into usable georeferencing data. And what might look like a few inconsequential clicks of the mouse for Gribben actually replaces hours and hours of conventional surveying data work. Using mdInfinity, part of the complete Microdrones system, the user moves into geocoding and, in short order, produces a point cloud from which a surface can be extracted for a deliverable to the client.

“If a picture’s worth a thousand words, add a picture plus a couple billion LiDAR points, and it’s worth even more,” Gribben said.

Adam Gribben, an sUAS Pilot and Survey tech at Adams Surveying, processes the LiDAR data in mdInfinity

Different applications helped Gribben perform tasks such as extracting elevation grids. Further features can be used to colorize LiDAR pointclouds to generate orthomosaics or colorize photogrammetric pointclouds. The end project is a deliverable that’s more accurate than traditional survey techniques and scalable to be delivered in a remarkably efficient manner.

“The Microdrones benefit is the scale of the project,” Adams said. “A lot of projects that we have can be 50 acres, but we do a lot of projects up to 1,000 acres. Microdrones just fits that particular criteria very well. Over the last 40 years of surveying, we’ve used a multitude of tools. This was just a tool I recognized very early on could be very beneficial to our business.”

If you would like more information on how to begin using drone surveying equipment, schedule a time to talk with one of our sales professionals.

You can also click the link below to watch the documentary-style reality series, Down to Earth, that features Adams Surveying working on these two projects.