Research on underwater target measurement technology based on sonar image and artificial landmark

Sonar imaging is one of the important means of underwater target detection. It can measure underwater targets and draw underwater topographic map. However, the existing methods can not rely on sonar images alone to measure underwater targets. In this paper, an underwater measurement technology based on sonar image is proposed. We combine the third-party reference object, artificial landmark to make up for the defects of sonar image measurement. The proposed method includes angle measurement method and three-dimensional mapping algorithm for size measurement. In the experiment, we combine image processing technology to restore the image contour information to obtain the key points in the sonar image. The experimental results show that the accuracy of this method can reach millimeter level, and the error range is within 5%. This technology realizes the shape correction and precise length measurement of underwater targets.