We should consider how we use drones more carefully

One of my favourite lines in the movie Jurassic Park is Jeff Goldblum’s classic: “Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.’’ This line is just as applicable to the people who build infrastructure in the real world as it is to the fictional lab workers who created dinosaurs. 

We have access to so much new technology today, but we shouldn’t be using it just because we can – we should be using it knowledgeably and safely, in situations where we know it can improve the way we do things.

Drones are a great example of a technology that is becoming easier to access, but should not be used just because it’s available. 

Take, for instance, the use of drones for topographical surveys of long linear features such as highways, rail corridors or pipeline routes, or large areas like towns and cities. There is a lot of talk on social media and at trade shows about “beyond visual line of sight’’ and how the affordability of drones will increasingly revolutionise large-scale mapping. This excitement over new technology can create a costly problem when the wrong data capture tool is offered to a client.

Surveyors should consider both manned and unmanned aerial platforms as options for projects. Contrary to popular belief, drones aren’t always the cheapest option, and technological innovation has not stood still in the manned aircraft domain; there have been large cost differences on linear projects of only a few kilometres, “flying’’ in the face of current hype. 

So, what are some of the characteristics of manned aircraft survey, and when do these traits become advantages?

Manned aircraft can carry heavy large-format cameras. This is important because large-format cameras capture more ground area per photo; fewer images require fewer ground control/check points and are faster to digitise (map) from. This creates lower ground control costs and lower processing costs. 

The larger image footprint for a given ground sampling distance, aka image resolution, also gives more freedom in placing ground control. This means it can be placed in public areas, avoiding the costs and disruption involved in traffic management and attaining landowner permissions to access private land. Manned aircraft can capture imagery from as little as 2cm-3cm ground sample distance.

Manned aircraft are much faster at acquiring images. Whilst the cost of mobilising drones to site is certainly cheaper than mobilising manned aircraft, once they’re in the air, the speed of survey is very different. The cost of having a drone crew in the field for multiple days to complete a task must be weighed against the initial cost of mobilising a manned aircraft.

Manned aircraft have pre-approval for most airspace. This reduces the admin costs involved in applying for special permissions to fly over critical infrastructure or urbanised environments and time needed for bespoke operational safety cases. The added height of manned aircraft also increases the separation and thus safety distance between ground objects and the platform for a given resolution.

Now don’t get me wrong, drones are a potent tool and certainly have their place – they permit aerial data capture at smaller scales and are excellent for targeted inspection work; they offer versatility and availability that manned aircraft simply can’t match. Indeed, last year, Atkins won a Brownfield Briefing Award for the ‘Best use of digital technology’ for our drone work with National Grid. This project showcased the power of drones, as we were able to map the site, visually inspect the gasholders and create a site video all using drones. We did this for eight sites in five days; traditionally this would have taken around six weeks and involved working at height. 

Technology is progressing at an exponential rate and we need to constantly challenge ourselves to leverage new tools and techniques to bring value to our projects. With changing regulations, direct image georeferencing, computer vision, automatic change detection, machine learning and automated feature extraction, I have no doubt that drones will continue to expand their realm of influence. But the spotlight on drones can’t blindside us to the innovations and value-adds of other technologies. It comes down to using the right tool, at the right time, in the right way. 

Charlton Bland is senior geomatics consultant at SNC-Lavalin’s Atkins business