Robust ViT-enhanced Detection of Sacrificial Anodes in Harsh Underwater Conditions

The structural assessment of submerged cathodic protection systems in Offshore Wind Turbines (OWTs) is crucial for ensuring longevity and operational efficiency. Traditional underwater inspections are expensive, inefficient, and expose human divers to hazardous conditions.This article aims to enhance the perception capabilities of underwater vehicles by introducing the Contextual Anode Locator in Varying Underwater Scenarios (CALVUS), a learning-based solution designed for the robust and precise detection of sacrificial anodes in harsh subsea environments. CALVUS leverages the feature extraction capabilities of a depth estimation ViT-based backbone to detect anode structures under challenging underwater conditions such as heavy marine snow, variable illumination, biofouling and motion blur.Evaluation on a dataset composed of images captured at the ATLANTIS Test Centre, CALVUS shows a performance of AP@50 of 97.9 %, an improvement of 19.9 % over state-of-the-art networks such as YOLO and RT-DETR. These results demonstrate the added value of using depth features during the detection operation, ultimately contributing to improved OWT operational efficiency and reduced maintenance costs.