Dr Eugene McGovern talks us through the use of UAVs in surveying.
Remote-control model aircrafts are familiar to most and have been around for years. ‘Drones’ are a modern, and technologically sophisticated, form of remote-control model aircraft. Most of us associate drones with the large pilotless aircraft used for military purposes in places like Pakistan. There is another type of drone referred to as an unmanned aerial vehicle (UAV) or, more correctly, a remotely piloted aircraft system (RPAS) that is of interest to the professional surveyor.
How they work
UAVs, in the surveying context, are small and very light remotely-controlled aircrafts, either fixed wing or multi-rotor, that typically carry a downward-looking camera. Advances in miniaturisation have enabled these aircrafts to be fitted with GPS, inertial measurement units (IMUs), robotic control systems, and telemetry links, while weighing around 1kg. The result is that an operator on the ground can remotely control the aircraft while viewing on a laptop the imagery being captured by the camera. Photography of the ground can then be captured by the operator on command. Autonomous flight and image capture is also possible, whereby a flight path, and required photograph locations, are selected on the laptop against a Google Earth background and this information is uploaded to the aircraft memory. After take-off, the aircraft flies directly to, and then along, the predetermined flight path and takes the required photographs. Sophisticated on-board control systems ensure that the aircraft maintains the predetermined flight path and elevation at all times, despite any buffeting from the wind. Associated software on the laptop can be used subsequently to stitch adjacent photographs to form a mosaic. The desired landing spot can also be dialled-in and that is exactly where the aircraft will land. Any reasonably flat open ground is suitable for take-off and landings. The simplicity, speed, and flexibility of UAVs sets them apart from conventional aircraft for acquiring aerial photography.
Uses in surveying
Uses for these UAVs that might interest surveyors include: capturing a birds-eye view of a property for sales promotion; checking boundaries; topographical mapping and contouring; generation of orthophotos; recording flood extents and providing measure-ups on quarries; earthworks projects; stockpiles; etc. Under ideal conditions, (optimal combination of flying height, camera resolution, ground control, etc.), positional and height accuracies better than 5cm are possible.
In addition to fixed-wing aircrafts, there are also multi-rotor systems, sometimes referred to as multicopters, that can hover very precisely and can be operated indoors or outdoors. They are particularly useful for mapping small areas or inspecting difficult to reach parts of buildings, bridges, or other structures. With both systems, further applications are possible by replacing the regular camera with a thermal or infra-red camera.
Legislation on the use of UAVs
There is a strict legislative framework that controls the use of UAVs which is controlled in Ireland by the Irish Aviation Authority (IAA). For UAVs weighing less than 20kg, including payload, the principal regulations are:
- the operator must be licensed by the IAA;
- visual line of sight must be maintained by the operator on the aircraft;
- the aircraft must always be within 500m of the operator;
- the aircraft must not be operated more than 120m above ground level;
- the aircraft can only be operated in congested areas with special permission from the IAA;
- the aircraft must not be operated within 150m of third parties on the ground; and,
- the aircraft can only be operated in ‘controlled airspace’ with special permission from the IAA.
In Ireland, there are currently 25 individuals licensed to operate UAV’s, with a further 15 awaiting licensing, and they offer UAV services on a commercial basis. The current regulations are designed with the safety of the public in mind, but undoubtedly restrict the use of UAVs. Internationally, and in Ireland, there are moves to revise the regulations governing the use of UAVs, to enable the enormous potential of these aircrafts to be more easily realised. When this happens, it is anticipated that larger UAVs, capable of carrying heavier payloads, will be developed for commercial applications. The smaller UAVs described above cost in the region of €10,000, but the larger UAVs under development could cost closer to €100,000.
Looking beyond surveying, UAVs have so much potential in so many disparate areas (for example, agriculture, forestry, surveillance and crowd control), that within 10 years they will be ubiquitous. Who knows, Amazon’s vision of UAVs delivering packages to your door might not be too far-fetched!
Dr Eugene McGovern
Eugene is a Chartered Surveyor and a lecturer in
the School of Surveying and Construction Management
at the Dublin Institute of Technology. He is a national
delegate to the International Federation of Surveyors (FIG)
and a past chair of the SCSI Geomatics Professional Group.