4 Top Reasons to Choose Drone Surveys

Corridor Mapping

Drone surveys are still a relatively new and not fully understood process for many people, but professionals in the engineering, exploration, surveying and precision agriculture fields are rapidly embracing the advantages of this alternative approach to gathering critical site data.

Where once they had to wait for a traditional surveyor to go out to a site, often spend several days there gathering ground-based measurements, then more days or even weeks compiling and presenting the data in a usable format, these early adopters are getting usable data in just a couple of days.

Even traditional surveyors are increasingly embracing drone surveys as a way of extending their reach and leveraging their time, often using a combination of traditional ground measurements and precise aerial measurements to quickly and efficiently survey large areas. We find ourselves increasingly working with traditional surveyors and partnering with them to certify the data collected from drone surveys.

So why are drone surveys becoming so popular? Why should you be considering drone surveys over traditional ground surveys, or even legacy manned aircraft surveys? Here are the 4 top reasons why drone surveys are taking over…

1. Drone Surveys are Faster and More Efficient

Not every survey should be completed using drones, just as ground surveys are not ideal for every situation. But there are many use cases where drone surveying is proving to be a faster and more efficient method of gathering site data.

As development and resource exploration extends into more and more remote areas of the country, drone surveys make more and more sense from a financial perspective.

The single biggest advantage of drone-based surveying is the speed at which data can be collected over large areas. The drone crew has to travel to and from the site, just as a ground survey crew would do, but once on site they can quickly and efficiently cover very large areas, capturing precision data that can be used as is, or validated against ground control points measured by a registered surveyor.

Where a traditional ground survey might be able to cover 50-100 acres per day, a drone survey can easily cover 500-1000 acres a day and more.

And where a traditional ground survey might collect 5-10 data points per acre, a drone survey is collecting 500-1000 data points per acre!

2. Drone Surveys are Safer

One of the biggest risks in ground surveys is workplace health and safety. In remote areas, especially, there is a big risk that ground survey staff may be injured by falls, vehicle accidents, snake bite or any number of other hazards, and because these sites are typically well away from ambulances and hospitals, help can be a long time arriving.

Contemporary HSSE best practice requires the development and implementation of strategies to minimise the risk of harm for personnel, especially when working on construction or mining sites and in remote areas. Drone surveys are one of the key methods of reducing staff exposure to site risks.

Yes, it’s true that drone survey teams have to work in the same risky or dangerous environments as ground survey teams, but it’s also true that drone survey teams only need access to a few key locations around the site, not to every part of the site (at least not on the ground). So there is inherently less risk in a drone survey.

Where a traditional ground surveyor might need to scramble over rocks or through dense vegetation to reach ground points that need to be measured for an accurate topographical profile, the same data can often be easily and safely captured from the air using drones launched from safe locations, then validated against ground data collected in safer, more easily accessible parts of the site.

This becomes even more critical when surveying large quarries or open cut mines where pit walls can be very difficult to reach and very dangerous to measure. But drone surveys can easily capture every detail of a pit wall or excavation, safely and efficiently, delivering data with much greater detail than traditional approaches.

3. Drone Surveys are Often Cheaper and More Cost-Effective

Are drone surveys really cheaper than ground surveys? It’s a no-brainer, right? If the data can be collected more quickly and efficiently from the air, there must be significant cost savings. Right?

Well yes and no. Anyone who claims that drone surveys can be completed for a fraction of the cost of ground surveys may not know what they are doing. It’s too easy for amateurs to pick up a drone at Harvey Norman and claim to offer aerial surveys, with little or no practical experience and relying on computer programs to automatically process the data (and with little or no idea if it is reliable or accurate, let alone in a usable format).

While this kind of operator might be able to deliver something resembling survey data, any reliance on that data comes with large financial and organisational risks for the purchaser. The data might come cheaply, but the cost of basing construction and engineering decisions on that data can be extremely high … and the operator probably has no professional liability insurance to compensate you for losses incurred through using their data.

Yes, drone surveys are often cheaper and more cost-effective than comparable ground based surveys for the obvious reasons, but they still require a similar level of professional skill, survey design methodology, ground-truthing, data processing knowledge and data verification expertise as a traditional ground survey, so make sure you’re getting that or it may not be as cheap as you think.

Professional drone survey service providers like Queensland Drones use experienced pilots and GIS analysts who understand how the data will be used by the client and can plan and execute their surveys to ensure client expectations are met. Our high quality GNSS RTK and PPK measurement systems mean we can collect and process survey data that can be readily used without surveyor certification. But where that data needs to be relied on for engineering decisions or cadastral purposes, we always work with a surveyor – your or ours – ensure it is reliable and verifiable.

The cost savings from a drone survey are significant, especially when larger and more complex or difficult sites are involved, but drones themselves don’t do surveys.

4. Drone Survey Data can be Just as Accurate as Ground Survey Data

Some traditional ground-based surveyors claim that drone surveys are not as accurate as traditional surveys, but there is little evidence that this is correct … and a growing body of evidence to the contrary.

Most traditional ground surveying still relies on the use of an RTK base station and RTK ground rovers to collect data points using triangulation of satellite data, which is then corrected using either the base position or remote correction signals, or both. Ground survey positions can be more accurate simply because the observation times are much longer – often 30 minutes or more, sometimes several times at the same location over the course of a day. And that’s why ground surveys are so expensive and time-consuming.

It may surprise you to know that professional drone surveys use almost the same measurement systems as ground-based surveys. Our professional mapping drones are equipped with multi-constellation GNSS GPS systems that collect triangulation data from 30-40 satellites every time they capture an image. This data is corrected using a multi-constellation GNSS base station whose position is accurately established either by placing it over a known survey point, using corrections from a remote network or using the same 30-minute or longer observations as a traditional surveyor, then validating the base position after the survey using a remote corrections network. This is a long-winded and complicated way of saying that, done correctly, drone surveys can produce very precise ground measurements.

Because drone survey accuracy is theoretically a factor of ground sampling distance (warning … more technical stuff coming), there are limitations to the precision a drone survey provider can reliably claim. While a ground surveyor may tell you they can measure points to an accuracy of 5mm, these points are often metres apart, sometimes much more, and are “extrapolated” across the ground between the measured points, so while they may be that accurate at the measured points, that may not be true in between.

Nominally, a drone survey can only be accurate to twice the ground sampling distance (GSD) horizontally and three times the GSD vertically. That means if the drone is collecting data at 3cm GSD, the nominal real world precision of the output is 6cm XY and 9cm Z. But even that accuracy can be compromised in many ways by pilot error or processing errors that often go untracked.

Queensland Drones can capture aerial drone survey data at 1cm per pixel and even less. This means our nominal real world precision is 2cm or less X/Y and 3cm or less Z. We use precision “terrain-following” data capture techniques to ensure the GSD is maintained even when mapping sites with large elevation changes. Like a ground surveyor, we do “extrapolate” elevations between data points, but as we are collecting thousands of points per square metre, the precision between those points is usually much better.

Our precision aerial surveys are backed up by measured ground control points and checkpoints. Even with precision PPK image capture and PPK or PPP correction of those image positions down to 1-2cm accuracy, we prefer to have ground data points that can be used to either provide additional corrections where some image distortions may occur, or to validate the accuracy of the captured data. Where these points are measured by a traditional surveyor, the validation often indicates aerial data capture accuracy of 5-10mm at those measurement points.

How to Find Out if Drone Surveys Can Work For You

Drone surveys are not ideal for every situation, just as ground-based surveys are not required for every situation. With more than six years of professional commercial aerial survey experience, our team can help you to decide if a drone survey is right for your particular requirements and if it is the most cost-effective option to get what you need.

Complete the form below, or give us a call on 1300 677 183 for a no-obligation discussion of your survey requirements.

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