Vessel Freeboard Calculation Method Based On Laser Scanning

China is a big country with very rich water transportation network, so the waterway transportation is very developed. In recent years, affected by domestic economic transformation and production adjustment, the vessel overload problem in inland river shipping industry is increasingly apparent, which has brought very bad influence to the transporting safety. Maritime sector takes vessel freeboard value as the primary standard to measure whether the ship is overloaded or not, so vessel freeboard measurement and calculation has become an important topic to concern. This paper presents a freeboard measurement solutions based on laser scanning, research contents are as follows.Vessel freeboard is defined as the distance from the water to the deck of the vessel. In order to obtain more accurate values of vessel freeboard, this paper proposes vessel freeboard calculating method based on Hough transform and mean shift algorithm. This algorithm uses the model of water to separate the water data and vessel data, and then calculate the height of the water and the height of vessel freeboard. In the calculation of the height of vessel freeboard, the algorithm uses the hough transform and regional growth method to extract the deck data and calculate the value of the vessel freeboard based on mean shift method.On the basis of the above algorithm, using dual sensor technology to optimize result. This section uses a dual sensor decision algorithm based on na?ve bayes classification to optimize the value of vessel freeboard. Firstly, It need to analyze and extract the characteristics of the vessel, and then the algorithm use these characteristics and na?ve bayes algorithm to choose which of the sensor measurement results close to the real value.This article relates to ultra-draft vessels automatic detection system has officially running in the Yangtze river. The system includes data acquisition module, video detection module and freeboard measurement module. At present, the system detects a daily average of more than 120 peer-ship fleet and the average detection error is 7 cm. The system can meet user requirements, and it is stable and reliable. This not only helps the Maritime section to manage the shipping safety, but also effectively curb the occurrence of ship violation behavior.