Sea Wave Measurement At Long Distance Based On 3D Image Processing

This research is an important part of a 3D image sea wave height measurement system.The system is designed to realize tsunami alarm by measuring wave heights based on stereo vision method and has a high demand for image quality.Researches done at close distance(less than 100m)had obtained the height of sea waves with high accuracy.To promote the project progress to finally achieve the purpose of tsunami forecast,this paper extends the measurement distance to long distance(over 3KM).The extension of distance contributes to much smaller sea waves and more difficult to recognize sea waves.To obtain 3D information from the long distance stereo images,this paper divides the process into two parts:sea wave extraction and sea wave matching.The arrangement of this paper is mainly about these two parts:For the long distance sea wave matching,this paper investigated on algorithm based on block factorization which set double thresholds in each block and the thresholds are varied according to different blocks.This method can extract sea waves from long distance images.For the long distance sea wave matching,this paper proposed a sea wave matching instead of direct point matching due to the difficulty and inaccuracy of direct point matching.Two sea wave matching algorithms are investigated,one is based on template matching and the other one is based on sea wave feature matrix.The latter behaves better on accuracy of matching with the increase of sea wave number.Experiments targeted on Japan sea had been conducted many times,3D information obtained with these methods draw the sea level trends of certain day.The trends attribute to the tide data from the government which approves the applicability of this long distance sea wave measurement.This method can provide a good basis for the 3D information calculation latter.