ABSTRACT With the continuous development of the water transportation and shipping industries, the number of ships in rivers has steadily multiplied, followed by the increasing complexity of the ship routes. These changes have highlighted the growing importance of ship detection and water level measurement systems. Such systems not only enhance the management efficiency of waterborne traffic, ensure navigation safety, and reduce congestion and collision accidents, but also effectively safeguard the integrity of riverside and bridge structures. Ship detection and river elevation measurement based on 3D point clouds can directly acquire depth information without being affected by lighting conditions. So it has a good research prospect. Therefore, this paper proposes a novel ship detection algorithm based on improved PointRCNN and a novel method for riverbank line extraction and water level measurement based on 3D point clouds, respectively. For ship detection, the improved PointRCNN algorithm can increase the performance of data processing and keypoint extraction techniques, and make the network to keep more foreground point clouds and learn more effective features. This improves the recognition capability of distant ships. Compared to the original PointRCNN algorithm, the improved PointRCNN algorithm has achieved a 3.84% increase in detection precision in practical scenarios. Regarding riverbank extraction and water level measurement, the proposed method based on 3D point clouds can directly extract riverbank lines with depth information, obtaining water level height without direct contact with the river surface. Within a distance range between 15 and 45 m from the LiDAR, the average absolute error using this measurement method is less than 5 cm, demonstrating the good detection accuracy of this method.
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