一种基于小波变换的三维网格模型水印算法

提出了一种基于小波变换的强壮三维网格模型数字水印算法。首先采用一种平面参数化算法将三维网格模型映射为二维参数网格，三维网格模型表面的几何信号相应转换为二维信号，然后采用一种自适应小波水印算法加入水印。实验结果显示该水印算法能够抵抗各种几何信号处理攻击。     

基于SVD的抗几何攻击数字水印研究

简单介绍了数字图像水印的原理、作用及其常用几何攻击方法,并指出通常的水印算法并不能很好地抵抗几何攻击,使得这些算法的适用性受到很大的限制。针对几何攻击,结合SVD分解在图像处理方面所具有的特性,实现了一个基于SVD分解的数字图像水印嵌入和提取方案,经过实验数据分析,可以有效地抵抗常见的旋转、镜像、平移、剪切、高斯滤波、JPEG压缩等攻击方法。     

基于分块SVD和Zernike矩的鲁棒图像水印

图像水印的抗几何攻击能力仍是目前数字水印研究中尚未很好解决的问题.本文引入Zernike矩,提出了基于分块SVD和Zernike矩的鲁棒图像水印算法.对原始图像进行预处理得到一标准图像,然后进行分块SVD.将置乱后的水印信号逐比特自适应地量化嵌入到各子块的最大奇异值中.水印的提取是水印嵌入的逆过程.采用Zernike矩估计旋转角度并旋回,以提高水印检测性能.实验结果表明,本文提出的算法的图像保真度较好,并且对缩放、旋转、剪切等几何攻击有较强的鲁棒性.     

基于多分辨奇异值分解包和随机森林的电能质量扰动分类研究

为解决电能质量扰动的分类问题,利用多分辨奇异值分解(Singular Value Decomposition, SVD)的信号逐层分解方式,提出基于多分辨SVD包与随机森林(Multi-Resolution SVD and Random Forest, MRSVD-RF)的电能质量扰动分类方法。通过实验证明了该算法对单一和复合电能质量信号的分类效果明显优于分解结构相似的基于的小波包的信号分解方式,比较了分类器模型的选择和特征提取数量对算法性能的影响。     

基于特征均值的SVD信号去噪算法

根据矩阵奇异值分解原理,提出基于特征均值的信号去噪算法。该算法首先构造出加噪信号的Hankel矩阵,并对其进行SVD变换,再将小于全体特征值的均值的那些特征值置零,最后通过SVD反变换重建出去噪后的信号。通过与传统小波和FFT信号去噪算法进行对比实验。结果表明,该方法具有较强的噪声鲁棒性,同时能更好地保留信号细节,但实现速度有所降低。     

基于小波分解的SVD水印算法分析

近年来,SVD(奇异值分解)在数字水印领域的应用越来越广泛,鉴于它的特殊性,越来越多的人把它作为提高水印系统不可见性和鲁棒性的主要手段。该文提出了一种基于小波分解的SVD水印算法,经实验分析,该算法对几何失真有很强的抗性,同时对噪声和滤波等非几何失真也有不错的抗性鲁棒性。     

相干信号源DOA估计ESPRIT改进算法研究

ESPRIT算法是空间谱估计中的经典算法,算法仅适用于非相干信号。提出了一种基于SVD思想的ESPRIT改进算法,算法对接收数据阵列的协方差矩阵进行特征值分解,取能代表信号全部信息的最大特征值所对应的特征向量,并将它按照一定的方式进行矩阵重构,对重构后的矩阵进行SVD分解,从中取出信号子空间,然后按照LS—ESPRIT算法求解。通过大量仿真结果表明：该算法适用于解相干信号,并且效果优于基于空间平滑思想的改进ESPRIT算法;在解非相干信号的时候,改进算法效果优于常规的LS—ESPRIT算法。     

一种基于SVD和改进自适应算法的科氏流量计气体信号频率解算方法

频率解算是科氏流量计气体信号处理的首要任务。针对实际应用中气体信号信噪比低、频率波动大的特点,本文提出了一种基于SVD和改进自适应算法的科氏流量计气体信号频率解算方法。首先利用SVD对气体信号降噪并重构原信号,然后应用改进自适应算法处理重构信号,解算出频率。仿真及实验结果表明,本方法可以获得更快的收敛速度和更高的频率跟踪精度。     

一种改进的DCT和SVD联合的数字图像水印算法

结合奇异值分解(SVD)和离散余弦变换(DCT)的特点,本文提出了一种改进的DCT和SVD联合的数字图像水印算法。该算法能够很好地解决透明性和鲁棒性之间的矛盾。算法中按Z字型选取低频系数,再结合SVD分解的方法嵌入水印,不仅增加了嵌入的信息量,而且提高了水印的安全性。实验结果表明,该算法不仅具有较好的透明性,而且对常见攻击如叠加噪声、JPEG压缩、滤波以及几何攻击等具有较好的鲁棒性。     

基于SVD的BOTDA测温系统的解调算法研究

基于布里渊光时域分析(Brillouin Optical Time Domain Analysis, BOTDA)的分布式光纤传感器具有测量范围远、精度高、可测温和测应变等优势，目前在大范围、长距离传感领域中广泛应用，如桥梁、建筑、道路等。然而目前大部分布里渊散射信号都是运用洛伦兹拟合算法进行寻峰解调，解调精度受噪声影响较大。提出一种基于奇异值分解(Singular Value Decomposition, SVD)的降噪寻峰算法，利用Hankel矩阵对测温信号进行升维，对BOTDA测温系统的仿真信号进行分解，并通过实验验证了利用SVD对测温信号降噪来提升测温精度的可行性。     

Watermarking 3D mesh by spherical parameterization

In this paper, a robust 3D trianglular mesh watermarking algorithm is presented by applying spherical parameterization. First, we transform the coordinate signals of the 3D triangular mesh into spherical signals using a global spherical parameterization and an even sampling scheme. Then, spherical harmonic transformation is used to generate some data for embedding watermarks. As a result, the watermarks can be embedded in the Fourier-frequency domain of the original mesh. Experimental results show that our watermarking algorithm is robust since watermarks can be extracted without mesh alignment or re-meshing under a variety of attacks, including noise addition, crop, filtering, enhancement, rotation, translation, scale and re-sampling.     

Geometric signal compression

Compression of mesh attributes becomes a challenging problem due to the great need for efficient storage and fast transmission. This paper presents a novel geometric signal compression framework for all mesh attributes, including position coordinates, normal, color, texture, etc. Within this framework, mesh attributes are regarded as geometric signals defined on mesh surfaces. A planar parameterization algorithm is first proposed to map 3D meshes to 2D parametric meshes. Geometric signals are then transformed into 2D signals, which are sampled into 2D regular signals using an adaptive sampling method. The JPEG2000 standard for still image compression is employed to effectively encode these regular signals into compact bit-streams with high rate/distortion ratios. Experimental results demonstrate the great application potentials of this framework.     

A novel 3D mesh compression using mesh segmentation with multiple principal plane analysis

This paper proposes a novel scheme for 3D model compression based on mesh segmentation using multiple principal plane analysis. This algorithm first performs a mesh segmentation scheme, based on fusion of the well-known k-means clustering and the proposed principal plane analysis to separate the input 3D mesh into a set of disjointed polygonal regions. The boundary indexing scheme for the whole object is created by assembling local regions. Finally, the current work proposes a triangle traversal scheme to encode the connectivity and geometry information simultaneously for every patch under the guidance of the boundary indexing scheme. Simulation results demonstrate that the proposed algorithm obtains good performance in terms of compression rate and reconstruction quality.     

Visual Salience-Guided Mesh Decomposition

In this paper, we propose a novel mesh-decomposition scheme called "visual salience-guided mesh decomposition". The concept of "part salience", which originated in cognitive psychology, asserts that the salience of a part can be determined by (at least) three factors: the protrusion, the boundary strength, and the relative size of the part. We try to convert these conceptual rules into real computational processes, and use them to guide a three-dimensional (3D) mesh decomposition process in such a way that the significant components can be precisely identified and efficiently extracted from a given 3D mesh. The proposed decomposition scheme not only identifies the parts' boundaries defined by the minima rule, but also labels each part with a quantitative degree of visual salience during the mesh decomposition process. The experimental results show that the proposed scheme is indeed effective and powerful in decomposing a 3D mesh into its significant components     

面向3D网格模型的多重数字水印算法

为了解决单盲水印网格算法难以抵抗多种攻击的问题,提出一种鲁棒的3D网格模型的多重数字水印算法.该算法分别对3D网格模型的顶点信息和拓扑信息嵌入2种不同类型的单鲁棒性水印,从而使模型既能抵抗大面积的剪切攻击,又能抗击一定强度的噪声攻击;且在水印提取时不需要原始模型信息.实验结果表明,该算法能有效地提高水印抗平移、旋转、缩放、非均匀缩放、剪切、噪声和顶点乱序等攻击的能力.     

基于局部故障块三维mesh/torus网的容错路由

当系统包含很少的故障点时．mesh/torus网整个系统就有可能是不可靠的．该文采用扩展的局部可靠性信息来指导三维mesh／torus网的容错路由．扩展的局部可靠性信息在每个平面内部对无故障节点分类，所以系统中的故障块也是在不同的平面上构成的，而不是基于整个系统．很多基于整个系统不可靠的节点在二维的平面中都会变成可靠的节点．不管是在可靠的系统内，甚或不可靠的系统内，扩展的局部可靠性信息都能有效地指导容错路由．不同于以往的方法，作者的方法不会将任何无故障节点设置为无效节点．所有的故障块都是在平面内构成的，而不是基于整个系统；在一个平面内．任何包含在故障块里的无故障节点仍然可作为出发点或者目标点，这样将大大提高系统的计算能力和性能．模拟结果表明该文方法大大优于已有的方法．     

基于表面粗糙度的三维模型质量评价研究

数字水印的嵌入会引起三维模型数据的失真,正确评价含水印三维模型的质量可以为三维水印算法的测评提供统一标准。提出了一种新的三维模型质量的评价方法,它首先利用网格模型中二面角为基本度量单位计算出整个原始三维模型的粗糙度,然后在嵌入水印以后用同样的方法计算出含水印三维模型的粗糙度,最后得到嵌入水印前后粗糙度的增量,并将其作为水印嵌入对三维模型造成的失真度的度量。大量实验结果表明,相比传统的质量评价方法,该方法更加适用于三维网格模型。该质量评价方法还可用于评价各种水印攻击对含水印三维模型造成损害的程度。     

Double watermarks of 3D mesh model based on feature segmentation and redundancy information

This paper presents a new robust, blind and good imperceptibility 3D mesh double watermarks algorithm. Two different kinds of watermarks are embedded into one 3D mesh model. One watermarking algorithm based on mesh feature segmentation and the DCT transformation, the other based on redundancy information of 3D model. The two watermarks do not disturb each other during embedding and extracting. Several mesh models are applied to test the robustness, imperceptibility and efficiency of the proposed algorithm. The experimental results show that the proposed watermark scheme can not only keep good imperceptibility but also resist various attacks, such as similarity transformations (translation, rotation, scaling and combinations of the three operations), file attack, signal processing attacks (noising, smoothing and vertex coordinate quantization) and connectivity attacks (cropping).     

Composite freeform surface reconstruction using recursive interpolating subdivision scheme

Composite freeform surface reconstruction from 3D scanned data of a physical model has become a more and more important topic in the field of CAD/CAE/CAM. By repeated application of a fixed set of recursive interpolation subdivision schemes on the initial mesh of the 3D sparse scanned data of a physical model, a polygonal model of composite freeform surface can be constructed. In the paper, the algorithm for constructing the initial triangular mesh from 3D sparse scanned data is presented. The unified recursive interpolating subdivision scheme for triangular mesh is proposed. A special quad-tree data structure is suggested to store all the necessary information of the vertices and elements of the polygonal model. Examples of composite surface reconstruction are provided to explain the distinguished superiority of subdivision scheme for reconstructing the arbitrary topological complex surface.