Abstract
Abstract. Marine surveying and mapping is the basis of all marine development activities, and underwater topographic survey is one of the essential tasks of it. The multi-beam sounding system can give dozens or even hundreds of water depth values in the vertical plane perpendicular to the course at a time, and there is a lot of redundancy in these data. Efficient compression can make better use of water depth data, improve work efficiency, save system hardware resources, and facilitate rapid mapping and the construction of submarine topography model. Thinning requires an optimal balance between data accuracy and sampling density. In this paper, several commonly used thinning methods are selected and applied to the sounding data for experiments, and the application effects of different thinning methods are analyzed and compared. The results show that the mesh-based and system-based thinning methods are simple and efficient, and the results are more evenly distributed. It works well in areas with flat topography and low complexity. But in the area with large relief, the result of thinning may not take into account the topographical features, and the effect of topography representation is poor. The thinning method based on distance and elevation difference takes the elevation factor into account and has a better performance in preserving topography features. However, this method needs to search the points in a given range constantly, and it is inefficient to apply it to large amounts of data. The thinning method based on the Douglas-Peucker algorithm only considers the spatial relationship within each ping data, and the thinning result is not reasonable enough. This paper can provide reference for sounding data thinning.
Highlights
Marine surveying and mapping is the basis of all marine development activities, and underwater topographic survey is one of the essential tasks of marine surveying and mapping
2.2.1 Thinning Method Based on Grid: According to the depth data points and the measurement area, the spatial grid is established, and only one water depth point is retained in each grid (GAO Jianlin, 2001)
2.3 Selective Data Thinning Method the maximum distance is greater than the threshold value, this point is reserved, and the line segment is divided into two sections by this point, and the above-mentioned operations are respectively performed on the two sections until all parts are processed and the broken lines formed by each dividing point are connected in turn, which can be regarded as the approximation of the curve
Summary
Marine surveying and mapping is the basis of all marine development activities, and underwater topographic survey is one of the essential tasks of marine surveying and mapping. The multi-beam bathymetric technique can accurately and quickly measure the size, shape, and height of underwater targets within a certain width along the course, depicting the fine features of the seafloor topography and physiognomy reliably. It has the characteristics of large measurement range, fast measurement speed, high accuracy and efficiency, digitization of records and real-time automatic mapping. The theory and method of multi-beam bathymetric data thinning has become an indispensable key technology in multi-beam bathymetric data processing
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