Envelope Locally Weighted Best Estimate on multibeam echosounding error and X-NLMF denoising

In order to extract the regular interference contained in the multibeam echosounding and eliminate random noise, the novel Envelope Locally Weighted Best Estimation (ELWBE) and the improved NLMF (X-metric non local-mean filter, X-NLMF) methods are proposed. The experimental results show that ELWBE and X-NLMF can not only eliminate the random noise but also give the local optimal estimation on preserving details. Through the experiment, we discover a neglected interference existing in the local area of the central line of the heading. Such interference comes from the heaving and dipping errors, induced fluctuation errors caused by rolling and pitch and some unidentified error sources. The proposed methods lay a good foundation for the further offset correction.