UAVs, used in combination with photogrammetry, are an emerging innovative technology providing a new platform for the acquisition of low-altitude aerial imagery and mapping data. UAVs provide surveyors with the ability to create Digital Surface Models (DSMs) and orthophotos from aerial imagery, for mid-sized areas previously only accessible at higher costs and with longer planning cycles. UAVs are used in a variety of applications, such as large-area land surveys, volumetric surveys, and landfill inspections.
Photogrammetric surveys are flown at low altitudes - less than 120m – allowing us to achieve extremely high image resolution. The degree of overlap used for a particular survey will depend on the nature of the terrain and the degree of accuracy and ground coverage required. A higher level of accuracy can be obtained by using greater degrees of image overlap, but this requires more images and therefore increases flight times. We use specialised flight planning software to estimate the correct degree of overlap required to suit a client’s needs for accuracy.
The advantages of using UAVs in surveying
A UAV provides a remotely-controlled aerial platform for acquiring low-level aerial imagery, often from unique vantage points. It adds value in in being able to cover large areas quickly and operate when manned aerial surveys cannot be flown or it is difficult or dangerous to perform a ground survey. UAVs come into their own in many circumstances, for example:
- When survey areas are either difficult to reach, sensitive or dangerous
- When weather conditions make planning an aerial survey with manned aircraft impossible; with our UAV we can take advantage of even short periods of favourable weather, with minimal lead-in times
- For high resolution mapping and modelling – in ideal conditions it is possible to get down to a 3cm ground sampling distance (GSD)
- UAVs can cover up to 0.75 km² (75 ha) in a single short flight
- UAVs are fast and flexible – the logistics and operational requirements for a UAV are minimal. This allows for very flexible operations
- Fast turnaround of raw data to final DSM