Coastal monitoring assessment using a low-cost PPK-UAV setup for photogrammetric survey

Coastal monitoring is a notoriously difficult task, especially for a sandy coast due to its quick dynamic. Different methodologies are employed to estimate geomorphology changes in such environment. These approaches are generally based on: satellite, aerial and UAV images, airborne and terrestrial LiDAR, SAR images, classical topographic survey using total stations and/or GNSS receivers. The use of UAVs for geospatial data acquisition is becoming increasingly popular as this kind of platform can be an efficient and cost-effective survey tool for topographic mapping and measurements, especially for coastal areas. An UAV can be equipped with various lightweight instrumentations such as high-resolution cameras, thermal imaging cameras, LiDAR, etc. Furthermore, UAVs can be used to survey hard-to-reach areas, providing geometric measurements with a high spatial resolution that cannot be achieved by other platforms. In these areas the principal challenge is to establish Ground Control Points with an optimal geometric configuration since an operator would still have to reach the area of interest with a geodetic GNSS receiver. In recent years, several UAVs were equipped with multi-frequencies GNSS receivers, which allow to achieve centimetric accuracy in PPK or RTK mode.This work presents an assessment of the photogrammetric results using a UAV in PPK configuration, avoiding to setup GCP on the ground.