First Tests of the Altimetric and Thermal Accuracy of an UAV Landfill Survey

The drones allow to acquire geometric and thematic information quickly and with considerable operational advantages in close range surveys. The lower flight altitude, and the possibility of rapidly replacing the sensors between panchromatic, multispectral and thermal sensors allow the detection of useful characteristics for monitoring and control, even periodically, of areas with reduced size. This paper will show the first results of testing these technologies on a landfill in the various stages of its development to verify the applicability and achievable accuracy in this specific field of application. It will show how the metric accuracy of the altimetric information obtained and the possible information that can be inferred from the thermal coverage has been verified. To this end, the surface of the site was materialized through the installation of dozens of fixed photogrammetric markers, specially prepared for the purpose. Markers were surveyed with GNSS receivers repeatedly in order to assess the displacements due to natural landfill settlement. It was possible to verify beforehand that the accuracy is comparable with that obtained from GPS. More in detail, for optical imagery the precision evaluated using SFM on GCPs is 5 mm, but we estimated separately the accuracy on some CPs that is around 3-5 cm. On the other hand on thermal imagery the precision evaluated by rigorous model on GCPs is around 70 cm. while the actual accuracy is more complex to be estimated due to the little number of surely collimable CPs and so it will discussed more in detail in the paper. These preliminary results show that the technique can be properly calibrated to operate in such situations with technical and safety advantages without interrupting cultivation activities. Results could be developed in similar fields such as mining extraction and excavations of various kinds.