How large is it the area which can be surveyed with a unique flight?

Our UAV can cover a 10 km2 area with a unique flight of 45 minutes.

What is a UAV?

UAV (Unmanned aerial vehicle) is an aircraft able to fly thanks to a remote control or to a predefined planning of its own route. The UAV are also called drones, due to the characteristic noise produced during their flight.

How can the UAV be precise during the flight and spatially reference the images with accuracy?

The UAV uses the GPS technology (the most is the number of located satellites, the most is the precision). Moreover, it is necessary to identify on the ground a unique point with known coordinates, in order to spatially reference the image with the required accuracy.

Which are the advantages of a topographic survey performed by a UAV with respect to a traditional survey/aerophotogrammetry?

The use of a UAV for topographic purpose is useful if the area to be analysed is too large to be surveyed in a traditional way by theodolite, but it is too small for the application of traditional aerophotogrammetry, which would have a too high cost. With respect to a traditional flight, in fact, the UAV survey is cheaper.

Moreover, the use of a UAV allows to survey easily also inaccessible zones, such as unstable slopes with high declivity, or places where there aren’t reference points of easy identification.

How long is it the duration of the flight of the UAV?

Our UAV can cover a 10 km2 area with a unique flight of 45 minutes.

How long is the duration of the UAV battery?

The duration of the lithium battery of the UAV is 45 minutes. The UAV is able to come back to the basis if the battery is low. The recharge time of the battery is about one hour.

How can the UAV guarantee the perfect stability of the images?

The UAV turns down its propeller during shooting, in the way to eliminate the vibrations that could be due to the propeller rotation.

How much is the UAV weight?

The UAV weight is less than 700 g, (it is involved in the ENAC directive for drones with weight less than 25 kg) and therefore it can be easily launched by a single operator.

Does the meteorological conditions influence the flight of the UAV?

The UAV is able to flight and take photos also in presence of wind up to 45 km/h. Optimal conditions for the flight and aerial surveys are wind absence (to guarantee the complete stability of the aircraft in phase of shooting) and blue sky (to avoid the presence of shadows on the photos due to clouds). However, if a sufficient number of photos is taken over the analysed area, it is possible to remove the problems due to clouds presence and consequent shadows on the photos.

The UAV is able to come back to the basis if wind is too strong.

What does it happens if the UAV lose the GPS signal?

Even if the losing of the GPS signal is a very rare event, if it happens the UAV is able to keep flying in a circular way around the point where it has lost the signal, until it finds again the signal. If not, it is able to land smoothly following a circular path at slow speed, in order to minimize possible damages.

Which products is possible to obtain processing the images acquired by the UAV?

Processing the images acquired by the drone through a dedicated software, is possible to display the study area in a three dimensional view by means of a point cloud generation and to obtain orthorectified mosaics and Digital Surface Models (DSM) of the examined area. Then is possible to produce maps of some indexes calculated as RGB band ratios of the retrieved mosaic.

How much time is it necessary in order to obtain the results of the image elaboration?

The time for the restitution of the final result depends on different parameters: the most important are the extension of the investigated area and the resolution chosen for the analysis. Depending on the number of images and on accuracy, it is possible to have a first restitution of the orthomosaic after some hours since the image download. Anyway, a first verification of the quality of the images can be performed immediately after the flight mission.

Which is the precision that can be obtained on the ortophotos?

The best precision of the collected images is less than 3 cm as far as concern the ortomosaic, and less than 5 cm as far as concern the Digital Elevation model (DEM).

Which software is used for the images processing?

The software used by us in order to realize the mosaic of the images is Postflight 3D-EB.