Land Surveying With Drones – An Expert Discussion (Part 1)
In this Waypoint exclusive, four experienced geospatial professionals share their experiences of surveying with drones, covering: why they first considered adopting drone (or UAV/UAS) technology, what questions and concerns they had prior to buying, and what these unmanned aircraft have brought to their businesses. (Part 1 of a two-part conversation. Read Part 2 here.)
The land surveyors we spoke with boast several years and hundreds of flight hours of survey drone experience. They include:
- Rachel Kohlman, SLS, P. Surv – Project Manager at Meridian Surveys (Alta) Ltd. (Canada)
- Peter Williams, B.App.Sc (Surv) – Managing Director at 4D Surveying (Australia)
- Ryan McMahon, P.Eng., A.L.S. – Professional Engineer at Measurement Sciences (Canada)
- Brian Kerr, O.L.S., C.L.S. – Senior Project Manager at McIntosh Perry (Canada)
Hi folks. To start, please tell us a little about your background and experience, including what type of surveying projects you typically work on.
Williams: I’m a registered land surveyor with 25 years’ experience in land surveying, engineering surveying and spatial data, specialising in land development and construction. I am currently also a land surveying representative (ACT) for the Surveying & Spatial Sciences Institute.
Kohlman: My personal experience of surveying with drones has been on the legal surveying side; roads, subdivisions etc. On the whole, Meridian Surveys is a well-rounded surveying company with experience in all aspects of oil and gas, layout, and we specialise in pipeline surveys.
McMahon: I am a professional engineer and Alberta land surveyor. We started out at Measurement Sciences focused on precision and engineering surveys, monitoring structures for deformation and aligning industrial machines and equipment for physics experiments. Over the years we have expanded into legal land surveying, bathymetric surveying, aggregate volumes, and oil and gas surveying. The bulk of my time now is split between legal subdivision for multi-phase subdivisions and deformation monitoring.
Kerr: I have 42 years’ experience as a professional Ontario, Alberta, and Canada lands surveyor. My work has included working for the Canadian government on heritage sites in Ottawa, working on land development and natural resource projects, and railways, and I operated my own private surveying practice in Ontario for 23 years. During the past 10 years, I have worked as a senior project manager with McIntosh Perry Surveying Inc., an engineering and surveying company based in Ottawa, Canada. McIntosh Perry’s work is split evenly between legal (cadastral) surveying and topographic surveying for projects as diverse as highway and bridge reconstruction, large scale site servicing designs, and solar and wind turbine power generation projects.
What convinced you to start to implement this technology and start surveying with drones?
Kohlman: We saw this new product at the SLS AGM in 2014 and it caught our eye and imagination. We could tell that this was going to be a tool that would become necessary for land surveying in the future and we couldn’t wait to get in on this new technology.
Kerr: Using survey UAVs became an option for our business when it became clear we required both faster turnaround times and more detailed modelling of site topography on many projects. UAV mapping offers quicker, more complete mapping than ground survey methods in many cases, so that problem areas can be identified and addressed.
It became clear we required both faster turnaround times and more detailed modelling of site topography on many projects
Williams: I have always loved advances in high technology and this was a good addition to my land development business. Plus, I love new toys and being one of the first to use them!
What are the key benefits that survey drones bring to your company?
Kohlman: Using a survey UAS can be a real time saver for a lot of jobs and it enables us to get a very complete set of data, something that a crew in the field would have a hard time doing in a timely fashion. At times it can also really impact on safety. Instead of sending our personnel into a situation with steep grades or equipment that could potentially be hazardous we are able to avoid this by remotely collecting this data.
Williams: Drones have enabled us to create a new branch of our business, offering clients a very good product at cost-effective rates in comparison to conventional methods.
McMahon: We are able to generate our own current high-resolution imagery for areas where none is available. We are also able to use drones to produce quality surface models with very dense sampling.
Kerr: UAVs provide an affordable alternative to field survey personnel, allowing us to complete projects at a lower cost and with fewer staff, while acquiring data that is more complete over the majority of a site, and allowing the onsite staff to focus on specific areas which may require on-the-ground detail acquisition.
Drones have enabled us to create a new branch of our business, offering clients a very good product at cost-effective rates in comparison to conventional methods
What were any key questions or concerns you had about adopting drone technology and how did these play out in practice?
Kerr: Our chief question about surveying with drones was the level of accuracy possible, in comparison with what we were used to achieving using ground survey methods. We were also concerned with the reliability and stability of the aerial platform, and whether it would be possible to rely on mapping data points generated in forested areas or in open fields with crop or crop stubble present.
Our chief question about survyeing with drones was the level of accuracy possible, in comparison with what we were used to achieving using ground survey methods
Kohlman: Some of the things that we were concerned about were applicable uses, the paperwork involved with regulations, and getting clients on board and excited about this new product.
Williams: We were concerned about the ease of flying such systems and the learning curve involved, but this was very quick and we’re now extremely confident flying our UAVs. Our final questions concerned the cost and potential ROI, but we found that an eBee mapping drone pays for itself on a 1:3 ratio; we’re currently earning three to four times per month the cost of our drone’s leasing and insurance, so not taking into account any extra growth we’ll pay it off in less than 18 months.
What specific UAVs do you use and for what types of projects?
McMahon: We have three senseFly eBees that we use for the bulk of our work. These provide aerial imagery to complement site surveys as well as for DSMs on aggregate volume surveys. They’ve also been used to confirm natural boundaries. We also had an Aeryon Scout for four years, which was used for closer range imagery and smaller applications where the fixed-wing drone was not practical. We have a senseFly albris on order now too.
We also have multiple quadrotors by 3DR that we use for site images and short information videos. We have mosaic’d images from these units but it is not our first option for ortho-rectified imaging.
Kohlman: Currently our drones are another tool that we have available to offer—they work for some projects and for others they aren’t the right fit. We currently us a Draganfly X4-P and two senseFly eBees. The two drones are very different types of equipment and are better utilised for certain things: the Draganfly has been used for some smaller topographical jobs, as well as inspections, whereas the eBee has been used for jobs where we need topographical information on a larger scale.
Williams: We use a senseFly eBee RTK drone for large-scale mapping and 3D modelling of mines and construction sites, along with providing high-definition orthophotos. We also use a DJI Phantom with a 5.2mm lens on a GoPro for aerial photos of construction sites.
Kerr: We’ve currently only used the eBee flying wing. We have used it on projects where there is a mix of open and forested areas. Depending on the season, in leaf and snow-free conditions, for example, we have had excellent results in the open areas and predictably poorer results in forests, where we typically expect to supplement or replace the UAV data with ground-measured data.
We have done a relatively small number of projects to date, but we are continually looking for others on which to use the UAV. So far, we have used the UAV primarily for land development projects, as we’ve found we can achieve mapping accuracies sufficient for engineering predesign work in the preparation of preliminary servicing plans. Under ideal conditions, we have achieved vertical accuracies of better than 10 cm.
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