Digital Measurement System for Ship Draft Survey
In order to overcome the limits of visual observation widely used in ship draft survey, a digital measurement system based on image acquisition and processing is presented. The images of drafts are obtained by an image acquisition unit containing a high definition camera extended to the shipboard from the deck. The draft marks are digitalized in use of a multilayer neural network, and the draft lines are detected by means of color image segmentation algorithm. Finally, the ship's trim are identified based on the relative position of the draft line located at the digitalized draft marks, where the artificial influences are eliminated. The influences of wave may also be reduced by calculating the mean value of the ship's trim obtained from different images.