The Pros and Cons of Drone Surveying

Drone topography, also known as unmanned aerial vehicle (UAV) topography, is the use of drones for mapping and data acquisition or for taking measurements. It is mainly used by surveyors and engineers in the field of construction for land assessment and cartography. Drone topography can be done 90% faster than traditional surveying methods, and it is used to make high-precision maps and topography points. Companies use drone mapping to recognize errors in the workplace, track work progress, predict delays in schedules, etc. The collected data is processed using drone mapping software to create construction assets such as 3D models, 2D maps and digital elevation models, from which high-precision volumetric measurements and calculations are performed.

The drone collects high-precision data quickly, without the need for surveying personnel to walk over hazardous terrain or heights to collect the data. Drone mapping drones are made of red, green and blue (RGB) visual images for photogrammetric, thermal, LiDAR or multispectral sensors to collect aerial data. The various maps or results collected from drone topography are orthomosaic maps, the digital surface model (DSM), the digital terrain model (DTM) and contour maps. To perform a very precise topography with drones, it is essential to accurately indicate the position of a drone in flight. This can be done using ground control points (GCPs), a real-time kinematic study (RTK), or a kinematic post-processing study (PPK).

GCPs are known points available on the ground whose coordinates are known. GCPs allow the drone to provide accurate data about its location and the distance it moved between the two locations. PPK topography is a GPS correction technology that rectifies drone location data only after collecting and conserving the final survey data. This method can reduce field time and survey costs, as well as provide accurate and comprehensive data. However, drones have only small payload capacities, making it difficult to recognize or clarify the characteristics of the terrain without symbols. Nowadays, anyone who can afford to buy or rent the right drone and the necessary technology can use drones for aerial mapping.

To perform highly accurate drone inspections, it is essential to accurately pinpoint the position of a drone in flight. A company that specializes in drone technology will be able to help a construction company comply with these regulations, especially since those regulations may change given the relative novelty of drone technology. A licensed pilot and an aviation professional must oversee all drone inspection efforts to ensure that the drone's safety and flight path are not compromised. Unfortunately, “capturing precision” is a challenge for many people looking to use drones in topography and mapping. Many experts in unmanned aerial vehicles believe that the best way to learn how to use drones in industry is to first be an experienced surveyor or cartographer and then learn to apply drone systems to work. Drone technology is constantly changing and, as the power of its batteries expands, the use of drones in construction is becoming increasingly practical.

If a drone is used to capture an aerial image or video and then the data is processed using GIS software, a separate drone will be needed for each type of map being processed. Drones require training to be able to fly well, and aerial reconnaissance and scanning systems require more training and experience. The drone can also have sensors that measure the height of objects so that surveys can be carried out precisely. Ultimately, Adams believes that “workflows should be developed from the point of view of topography, and pilots who are dedicated exclusively to drones should work to collaborate with surveyors, rather than trying to face the industry as an individual”.