Study On Visual Technology Of 3-Dimensional Underwater Acoustic Data

The research and application of the visualization of underwater acoustic data provide strong technical support for the observation of submarine geomorphy,exploit ocean resources,underwater emergency and ocean military affairs.The data preprocessing of visualization of underwater acoustic and the design of transfer function of volume rendering were further studied in this article.The main research achievements of this article are given as follows:The 3D underwater acoustic data usually contains complex background and serious noise pollution.With regard to these features,this paper presented an underwater acoustic data segmentation algorithm via histogram fuzzy C-means(HFCM)with 3D fuzzy median filter(FMF)to improve segmentation accuracy and efficiency.In this study,first,a 3D filter window was selected,and the fuzzy threshold was calculated by the maximum entropy threshold method in the filter window.Then the underwater acoustic data was filtered by the FMF with the semi-Gaussian fuzzy membership function.Finally,the HFCM segmentation algorithm was adopted to segment the filtered data.The results of segmentation of two different groups of 3D underwater acoustic data showed that the effect of the segmentation algorithm was better than the unfiltered HFCM segmentation algorithm and the HFCM segmentation algorithm with equilibrium FMF.And the operation time was shorter than the traditional fuzzy C-means(FCM)algorithm distinctly.The underwater acoustic data segmentation algorithm via HFCM with 3D FMF can reduce the noise effectively and obtain a better segmentation result.In order to obtain a good display of underwater acoustic dada,an opacity transfer function and a color transfer function were designed.First,map the scalar of volume data into an opacity value.Then calculate the gradient of volume data and map the gradient magnitude into opacity value.And finally the 2D opacity transfer function based on scalar and gradient magnitude was designed.For another,a color transfer function was designed by mapping opacity,gradient magnitude and second derivative into HSV color space.The application of transfer function in volume rendering shows that the result of display strengthens the boundary information and highlights objects by gradient opacity transfer function.The design of color transfer function make the underwater objects been recognized easier.In this paper,first,volume data are processed by denoising and segmentation and the opacity transfer function and color transfer function were designed.Then the underwater acoustic data was rendered by ray-casting algorithm.The experimental results show that the research work of this paper can get good display effect of the underwater environment.The result not only highlights the target,but also maps the image much clearer and more conducive to the follow-up work of observation and analysis.