It is a photogrammetric survey aimed at obtaining a digital terrain model (DTM) + high resolution orthophoto of the landslide area covered by the Interreg V 2014-2020 project ID 489165 Fiume Tresa – Frana Cadegliano-Viconago.
The cross-border project was developed by the geomatics department by the University of Applied Sciences of Italian Switzerland which carried out a survey with a terrestrial LIDAR used to calibrate the digital model processed by the cloud of photogrammetric points.
The resolution of the Ortho-photo paper <5Cm / px also allowed to verify the depositional characteristics of the Tresa river
The area to be surveyed has an area of about 70Ha with a vertical drop of about 300m and has a remarkable tree cover; the survey was carried out at the end of the winter with a GSD of 4.37cm and a total of about 600 images were acquired.
The image processing led to the creation of a dense point cloud formed by about 40,000,000 points (with an average of over 53 points per cubic meter) from which a digital terrain model was generated with a pitch of 50 cm / px and an orthophoto map there about 5Cm / px.
The survey was georeferenced through 31 GCPs detected with a Trimble GNSS-RTK antenna that allowed to obtain an RMS error of 0.014m.
The dense point cloud and that generated by the terrestrial LIDAR survey were compared and gave an average error of 0.8Cm in the three directions.