DETERMINING FACTORS OF RESOLUTION AND ACCURACY OF RESULTS OBTAINED WITH DRONE
The use of drones to conduct surveys of georeferenced information has evolved over the past few years. It is so that today we can find in the market from commercial drone with flight autonomy of up to 30 minutes, useful for lifting land of small extensions, which also have limited capacities for loading payloads, to professional drones with flight autonomy of 70 minutes, useful for lifting large areas of up to 500 hectares per flight with the ability to incorporate various types of sensors, such as RGB of 20, 24 or 42 MPX, multispectral sensors, thermal imaging cameras, among others.
With this type of technology represents a great responsibility in the labor and professional field since the results of the work performed will depend largely on the choice made when acquiring one of these equipment, for this, it is necessary to take into account the type of works to be carried out, average extensions of land that is usually raised, drone autonomy to cover the entire required area and obtain efficient work, and also the type of sensor needed.
In many occasions, professionals or users acquire a certain type of drone either because it is simple to handle or the type of sensor it possesses; Although this statement is correct, it is not entirely true because the level of quality and detail that is obtained when carrying out the information surveys will depend on other parameters external to the equipment but not only on the characteristics of these.
An essential element to obtain good results from our surveys is the correct flight planning.
Within this, depending on the scale you want to work on or the resolution you want to obtain in the results, the flight height must be established taking into account the type of sensor that is on board. For example, in a work carried out for the water company INTERAGUA, two surveys were carried out with the Wingquad drone, the difference is that flight 1 had the 24 MPX camera and the second flight had the 42 MPX sensor incorporated. For this survey, it was necessary to obtain a GSD (Ground Sample Distance) in the orthomosaic of 5cm / pixel. As a result in the 2 surveys, a resolution of 5cm / pixel was obtained, however, to reach this end, flights had to be made at different heights. In the first case of the flight with a 24MPX RGB sensor, it flew at a height of 170 m, and on the flight that had the 42 MPX sensor built-in, it was necessary to fly at a height of 300m. Similarly, it is necessary to have the account of the necessary number of control points that should be placed on the ground depending on their extension, shape, and scale of work.
That said, the quality of results obtained will not only depend on the type of sensor that the drone incorporates, but also on the height at which it is flown, control points placed and flight plan made previously.
The other hand, it is not always necessary to acquire a sensor with higher resolution by the parameters mentioned above since it must be taken into account in the same way, that when incorporating a sensor with higher capacities, this involves the greater capacity of the computer or processing system that can store heavier data.
By: María Gabriela López
Geographical Engineer & Environmental Management
LAS Technical Coordinator & Sales Engineer
For more information visit: www.latitudeas.com
Phone: +1 347 960 6444