The Technoligy About Extracting And Arranging Isobaths From Multi-Beam Data

The development of ocean needs the marine spatial information database and bathymetric chart support. Cartographic generalization is a hot spot of research in the field of cartography. Especially, in the appearance of multi-beam system, which compared to the conventional single-beam echo sounder, the acquisition resolution of seabed terrain data has greatly improved. But the resolution enhancement has also brought the redundancy problem of massive data, which makes the cartographic generalization is particularly important. Traditional cartographic generalization is time-consuming and low efficiency. The results of automatic cartographic generalization by computer are often not good enough. With aim of the automatic extraction bathymetric and cartographic generalization, base on the point cloud data of multi-beam, this paper has accomplished the researchful task hereinafter:1. The survey principle and technical characteristics of the multi-beam system are introduced. At the same time.The multi-beam system data format and error sources have are discussed. Data processing is summarized, and isobath drawing algorithm and process are introduced as well.2. Point cloud filtering significance is summarized.The existing Multi-beam filter algorithm is studied.and the shortcomings of the existing algorithm are are pointed out.with aim of extracting Submarine terrain feature, the multi-beam point cloud is filtered by improved TIN progressive encryption algorithm.3. The paper reseaches the current algorithms of cartographic generalization for isobaths, summarizing three principle about the cartographic generalization for isobaths in marine mapping.Two algorithms(the double directional buffering algorithm and the improved Douglas-Peucker) of that have been choosen to research their theory and characteristic.4. Improved TIN progressive encryption algorithm and double directional buffering algorithm and improved Douglas-Peucker are programed. Experimental cartographic generalization by measuring multi-beam data to test the effect of algorithms, the point cloud distribution and the DEM and the iosbath are used to assess algorithms in this paper.Results of the above work indicate that, the improved TIN progressive encryption algorithm can extract points of seabed terrain features while undermine noise and the system errors of multi-beam data. The algorithm also can make the isobath more smooth. The two algorithms (the double directional buffering algorithm and the improved Douglas-Peucker) for iosbath cartographic generalization meet the three principles of cartographic generalize iosbath. and the two algorithms also help improve the efficiency of submarine topographic mapping. In the same case, the double directional buffering algorithm has more advantages.