Quay no. 2 at Dégrad-des-Cannes: pile verticality from 4,410 photos

Background

The Grand Port Maritime de la Guyane wanted to know the tilt of the piles supporting quay no. 2 at Dégrad-des-Cannes, in absolute terms and relative to one another. The piles can only be seen at low tide, under the deck, over a short height.

What we did

The port reserved the berth for the flights and arranged for the emerged part of the piles to be cleaned with a high-pressure jet to remove concretions and shells. The flights were carried out from a boat leaving the Dégrad-des-Cannes marina, at low tide on 2 and then 3 August 2023: the first produced the 3D model of the 200 m quay, which was used to prepare the close-range flight plan of the following day. In total, 4,410 photos taken with a 45 Mpx full-frame sensor, at 0.5 mm per pixel on average, and control points measured by GNSS. On the part of the quay framed by these points, two horizontal profiles at +0.4 m and −0.4 m NGG 77 were extracted from the model for each pile: their offset gives the direction and amount of tilt. Delivered on 29 August 2023: ortho-façade, PDF and DWG layouts, summary presentation.

In the mission log

1. September 2023

   InspectionFrench Guiana

   Photogrammetric survey of quay no. 2 and verticality check of the piles

   Dégrad-des-Cannes · Grand Port Maritime de la Guyane

   Piles photographed less than a metre above the water under the deck, 3D model and verticality analysis handed to the experts: “the result is impressive, great work”, wrote the port’s technical department.

All missions