How do we monitor our beaches?

1.    We survey Ground Control Points (GCPs) using high-precision GPS. Their coordinates will allow us to map the shoreline in the UTM reference system
   

2.    Anyone can take a picture of the beach and share it at coastsnap@unige.it. A metal cradle ensures a consistent viewpoint across different smartphones
   

3.    Photographs taken with different phones and cameras are aligned with a reference image, bringing them into common frame and size
   

4.    After resizing, images are processed using Meta’s Segment Anything Model 2 (SAM 2) to identify the sea–land boundary, starting from a selected wet pixel
   

5.    The detected shoreline is finally converted from pixel positions into geographic coordinates using the GCPs and the estimated camera projection. This allows to track shoreline changes and assess coastal flooding and erosion over time!
   

Francesco De Leo, Giovanni Besio, Guillermo Martin Llanes