Research On The Mosaic System Of Side-scan Sonar Image

In recent years, people put more and more emphasis on the development and utilizationof the marine, and the shallow water detection technology has become an important branch ofthe ocean exploration. Multi-beam side scan sonar technology is the main way to explore theshallow water. As the particularity of the sonar data acquisition, we can just get the singleimage without clear positional relationship between each PING data. The observation of theshallow water landscapes plays an important role in the ocean exploration, so it is urgent toget an approach to deal with the multi-beam side scan sonar data and provide a clear seabedtopography map with accurate geometric relationships. This thesis discussed on this issue andgave an effective method.Sonar data, in view of the special nature of the sonar echo principle, is influenced by themarine environment, marine life and ocean noise, additionally, the slant range also greatlyreduce the geographic information of sonar image, and increase the difficulty of drawingseabed topography. First, start from the principals of the data acquisition and analyses the datadecoding and filtering method. Distribute some common methods for the sonarhigh-frequency data and low-frequency data, then gave a method based on the Curvelettransform filtering, at last displayed the results.To draw a precise seabed topography, we first deal with the single PING data. We discusstwo main geometric correction: Slant range correction and speed correction. Then display theclassic methods and gave two reduced way. At last compare the result and gave out theconclusions.To give an overall seabed topography, it is necessary to take full advantage of geographiccoordinate information that provided from the sonar data in the header file, including thelatitude and longitude information, the ship heading and the Towfish heading. Afterconversion and correction of the GPS information, draw a complete and correct track line,according to the track line we can do the sonar image stitching. In the process of stitching, thedata should be rotated, stretched, a series of operations such as integration and interpolationshould be taken. After completion of the initial splicing, in order to improve the integrity andreadability of the seabed topography, we do the second patch, thus the re-draw of the sonarimage data is completed.After the side scan sonar image correction and fusion, we get the overall draw of theseabed topography, provides an effective method for the seabed topography.