Land Surveying With Drones – An Expert Discussion (Part 2)


Four experienced geospatial professionals continue their discussion of surveying with drones—including how they employ these aircraft day-to-day, the issues they have faced, and what buying tips they have for others who are considering bringing unmanned aircraft into their firms. (Read Part 1 here.)

As a reminder, the land surveyors we spoke with, who boast several years and hundreds of flight hours of survey drone experience between them, include:

Have your drones replaced any surveying instruments or workflows?

Kohlman: I wouldn’t say drones have replaced anything at this point. It is something you hear people jokingly say—“it’s going to take over your crew’s job!”—but while drones have taken a crew away from having to do a 5×5 grid on a piece of land or climbing gravel piles, the crew still has to be out there to tie in pins and search for evidence. With regulations the way they are, drones can’t be used for every job that you may like.

While drones have taken a crew away from having to do a 5×5 grid on a piece of land or climbing gravel piles, the crew still has to be out there to tie in pins and search for evidence

McMahon: They have not replaced much of our existing tools or techniques but have enhanced our overall product.

Williams: Not yet, we still use all our equipment. The drones are more an extension of our current workflows.

Kerr: We have been completing most of our topographic work using either total station or RTK GPS equipment (or a combination of both), depending on the accuracy requirements of the project. The eBee mapping drone’s data reduction software and ease of transfer into AutoCAD or Civil 3D software have shortened our office turnaround by many hours since so much of the data reduction is automated. We subcontract another firm to complete the data acquisition and reduction for us, and they deliver it to us in AutoCAD format within a day or two of flying the site.

Land Surveying With Drones - Lower Molonglo Dam_Canberra
Lower Molonglo Dam in Canberra, Australia, a drone mapping project completed by Peter Williams of 4D surveying.

Are there any current surveying techniques or instruments that you think future drone platforms might replace?

Kohlman: I feel like 3D scanners may take a hit as the pixel matching software makes progress. With a drone and a camera it is pretty amazing the data you can come up with.

McMahon: I expect that affordable heavy payload drones with high-precision lidar systems may cut back on the use of terrestrial-based scanners.

3D scanners may take a hit as the pixel matching software makes progress—with a drone and a camera it is pretty amazing the data you can come up with

Kerr: Though not a replacement, the addition of small lidar scanning equipment onto drones would greatly enhance the data acquisition process, moving the platform from solely a photogrammetric instrument into a 3D scanning instrument. Also, for a time Canadian research into inertial systems seemed promising, but the technology at that time was cumbersome and not very workable. New micro-technology may again make this possible, with miniature accelerometers available off the shelf.  A handheld INS unit would allow the possibility of ‘touch and go’ surveying in otherwise inaccessible areas such as underground, in forests, underwater etc. Surveying with drones will not necessarily replace instruments or techniques. They are more likely to become one element of larger solutions tailored to the specific requirements of individual projects.

Williams: Not yet.

What, if any, drawbacks or challenges have you had implementing survey drones into your work?

Williams: One challenge of surveying with drones has been building client confidence; persuading clients that drones work, they are safe and they will give them extremely good results. As a result, we had to offer our very first project at cost price.

McMahon: The most significant drawback is be the challenge of getting federal approval to fly the units commercially. Other than that, the overall volume of data has been a minor challenge to manage.

Kohlman: One of the main drawbacks we have faced so far would be downtime due to repairs. Public wariness has also been a bit of a challenge; clients are sometimes a little wary to have you use your drone with the public perception being that there is then an inherent lack of privacy (but as it is there are very detailed satellite photos taken every day). All and all these are some fairly new pieces of equipment; I am sure down the road things will become a bit easier all around.

How do you view the drone regulations in your country?

Kohlman (Canada): The regulations in place can be very helpful, if only for public and aviation safety. We have all heard about drones having close calls with planes and people. However, the current process with the regulations can be a bit cumbersome, which can really hold things back.

One of the main problems is that a lot of people don’t follow the current rules, whether it is the public or people in professional sectors. This lends a bad name to those of us out here trying to run things on the straight and narrow.

One of the problems is that a lot of people don’t follow the rules … this lends a bad name to those of us out here trying to run things on the straight and narrow

Williams (Australia): Here the CASA is very good, although in my humble opinion the regulations are not strict enough.

McMahon (Canada): In the years before 2015, the regulation process was difficult to achieve but was understandable. After having approval for three years, we are more confused than ever of what is expected of users and how to work within the guidelines. I would say the current regulations appear to less restrictive but in fact, are not.

Kerr: Transport Canada has taken a reasonably pragmatic but cautious approach to the use of commercial drones. Limiting aircraft size and altitude restrictions has been their initial steps towards preserving public safety; a necessary strategy. But as with any technology, there exists a risk of dangerous usage by uninformed and careless operators.

Land Surveying With Drones - DSM
A digital surface model generated from drone-sourced aerial images (image: Measurement Sciences).

What kind of drone regulations would you put in place if you could, and why?

Kohlman: We are in the business of land surveying with drones, not aviation. I wouldn’t want a pilot with a handheld GPS setting rules for surveying, so I think I will take the regs on this subject from the folks in charge of the skies!

McMahon: I would not be opposed to mandatory training for drone pilots that would be accredited by the government in an effort to expedite approvals.

Williams: I would demand that all commercial users gain CASA certification regardless of the weight of their drone. When it comes to safety, in my view, all drone users should compete on the same playing field.

I would not be opposed to a mandatory training for drone pilots that would be accredited by the government in an effort to expedite approvals

Kerr: I would suggest a certification process similar to pilot training, which requires a thorough knowledge of air regulations plus specific knowledge of the drone’s capabilities and limitations as an aircraft. Current ‘beyond-line-of-sight’ and ‘first-person view’ prohibitions effectively limit drones to small areas. They are the VFR of unmanned aircraft.  New regulations need to be conceived to allow responsible operators to work BLOS. Maintenance records and inspection regulations will be required as well—these are aircraft and need to be treated as such. There are also overflight permission and privacy issues to be dealt with.

What surveying equipment can you not see drones competing with?

McMahon: Precision levelling and optical tooling.

Kohlman: Basically the human factor. We will always need crews in the field to help in assessing evidence, digging holes, and pounding pins. As handy as a drone can be it is like any new piece of technology. Even GPS hasn’t completely replaced the total station, and there are times when you need to get out a tape and plumb bob.

Kerr: Drones cannot carry any currently available instruments that can see through bush or water (although they are being used to carry magnetometers). Generally, if it cannot be seen or sensed from the air, a drone is not the answer.

Williams: 3D scanning, GPS and robotic theodolites.

Generally, if it cannot be seen or sensed from the air, a drone is not the answer

How would you advise a professional who is considering surveying with drones? What should they look for in a system?

Kerr: I would suggest they look for the following: reliability, training and support, a 3 cm/pixel or better resolution, survey accuracy (i-3 cm horizontal, 5-10 cm vertical), flexibility in using survey controls, user-friendly software, think about power usage (considering a copter or a fixed-wing drone depending on the project), and a product that is ready to fly ‘out of the box’.

McMahon: Look at ease of use, the processing software included, and whether the drone is recognised or compliant with Transport Canada.

Kohlman: Find out what your target application is going to be and then shop around, ask questions and talk to your peers about their experiences. No matter what you’re wanting to do you are going to want something reliable, with a reputable safety record.

Williams: Do all the training first and buy a quadcopter to get your flight time experience up, allowing for around $10k in costs and downtime. Also, decide how you are going to use your system, do a lot of research and buy the best system for your business. Don’t buy cheap either, you will regret it.

And finally, any useful tips for new or future drone operators? Any lessons you’ve learned the hard way?

Kohlman: Be organised with your data, back it up before you process, and thin it out after you are done. It doesn’t take long to fill up hard drives and be swimming in excess data.

Williams: Always fly with an observer. Don’t fly in winds above 10 m/s (it’s not worth the extra hassle). Buy a mobile weather station, an inventor for batteries and back-up wings (eagles hate fixed-wing drones and will attack). Practice your bird avoidance methods—mine is to get the drone down ASAP and wait for the eagle to move on. Have a daily checklist ritual and perform good maintenance. And have fun, as working with drones is very cool!

Always fly with an observer

Kerr: Be conscious of flight restrictions, train a backup pilot to fly ‘hands-on’, stay away from highways where the unit can be a visual distraction, spend time understanding the radio links used, make sure cable connectors are compatible and understand the relative accuracies of the data acquired.

McMahon: Ground truthing and adequate targeting are as important as they are with traditional photogrammetry. Get a more powerful PC as a dedicated photogrammetry machine to process some of the larger projects. And start your application with Transport Canada three to five months before your flying season.

Land Surveying With Drones - Flight Planning
Ryan McMahon of Measurement Sciences prepares to launch.

Thank you all for your time!

Read Part 1 of Land Surveying With Drones

Learn more about the potential of surveying drones 

Explore drone survey case studies

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Comments (4)

Thanks for sharing

I found it very interesting that they are able to contour to the land now since we have drones and such that could really find the best places to build everything. I’ve heard a lot about surveying and how helpful it can be in society, especially when it comes to saving money. It sounds like a surveyor would be very crucial to a building project because they’ll know and understand everything that is needed in the build.

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