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Mathematical Problems in Engineering
Volume 2013, Article ID 101837, 12 pages
Research Article

Automated Visual Inspection of Ship Hull Surfaces Using the Wavelet Transform

Universidad Politécnica de Cartagena, Campus Muralla del Mar, 30202 Cartagena, Spain

Received 22 February 2013; Revised 29 April 2013; Accepted 6 May 2013

Academic Editor: Wen-Jer Chang

Copyright © 2013 Carlos Fernández-Isla et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A new online visual inspection technique is proposed, based on a wavelet reconstruction scheme over images obtained from the hull. This type of visual inspection to detect defects in hull surfaces is commonly carried out at shipyards by human inspectors before the hull repair task starts. We propose the use of Shannon entropy for automatic selection of the band for image reconstruction which provides a low decomposition level, thus avoiding excessive degradation of the image, allowing more precise defect segmentation. The proposed method here is capable of on-line assisting to a robotic system to perform grit blasting operations over damage areas of ship hulls. This solution allows a reliable and cost-effective operation for hull grit spot blasting. A prototype of the automated blasting system has been developed and tested in the Spanish NAVANTIA shipyards.