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1.
三维网格模型增量式聚类检索   总被引:1,自引:1,他引:0       下载免费PDF全文
针对大规模三维网格模型库中的形状检索问题,提出了基于增量式聚类的三维形状描述和检索方法。首先根据三维模型的曲率分布直方图提取特征点得到特征向量;然后根据特征向量描述建立模型库的关键词词典;在特征 匹配阶段基于增量聚类方法判断目标模型的特征向量是否属于某一个关键词,并根据增量聚类的结果更新检索关键词词典;最后匹配特征向量检索模型库中与目标模型形状相同和相近的三维网格模型。相关实验结果证明了该方法快速有效,具有较高的准确性。  相似文献
2.
两种抗几何攻击数字图像水印算法分析及比较   总被引:1,自引:0,他引:1       下载免费PDF全文
以图像归一化和不变质心理论为基础提出了两种安全性较高的数字图像水印算法。为了增加水印的隐秘性及抗干扰能力,水印在嵌入前均进行了置乱和混沌加密处理,然后两种方案分别根据其归一化图像的不变质心确定出相应的重要区域,并在该区域实施水印的嵌入。实验结果表明,提出的两种数字图像水印算法均具有较好的不可感知性和抗攻击的鲁棒性,且在抵抗常规信号处理和几何攻击下各具优势。  相似文献
3.
基于复合超混沌系统且与明文相关联的图像加密*   总被引:1,自引:0,他引:1       下载免费PDF全文
为了提高加密系统的抗攻击能力和加密安全性,分析了现有图像加密的方法,提出一种改进的图像加密方法。对Clifford超混沌系统和Logistic混沌系统进行嵌套组合,产生了具有更好特性的Cli-Log混沌系统,用于图像的位置置乱;在Chua超混沌系统的龙格库塔解法中插入参数,生成混沌序列与图像像素值进行异或操作,实现加密。该加密算法不但生成随机性较好的序列,而且增大了密钥空间,最重要的是这些插入的参数来自于前面用于置乱的混沌序列,实现了密文反馈。计算机仿真结果表明,该加密算法具有良好的加密效果,克服了大量加密算法只与混沌系统及密钥有关而与明文无关的缺点,使加密安全性进一步提高。  相似文献
4.
为克服Mean Shift算法复杂度高、速度慢的缺点,提出了一种改进的三维网格模型Mean Shift并行分割算法.该方法基于Mean Shift的基本思想和GPU的高性能并行计算能力,基于离散测地距离的局部极值提取三维网格模型的显著特征点,自显著特征点开始并发执行Mean Shift算法,实现了有意义的分割.与同类算法相比,该算法提高计算运行效率、改善了分割效果.  相似文献
5.
In some scattered point cloud triangular mesh restoration algorithm, small triangular mesh holes problem will often affect the quality of the model. For small holes at the details, this paper propose a method for identifying and extracting hollow edge,and use a triangle growth way based on boundary edge angle to fill the empty void. First, according the relationship of the point, side and face of the triangle mesh model to identify the hole, then extracting the holes boundary edge and classifying it. Finally, using a triangle growth method based on holes boundary edge angle to fill each small holes separated from the boundary. Compared with other algorithm of filling holes, this method is high efficiency for small holes of smooth surface,and itimprovesthe quality of the triangular mesh model.  相似文献
6.
In order toovercomethe poor local search ability of genetic algorithm, resulting in the basic genetic algorithm is time-consuming, and low search abilityin the late evolutionary, we use thegray coding instead ofbinary codingatthebeginning of the coding;we use multi-point crossoverto replace the originalsingle-point crossoveroperation.Finally, theexperimentshows that the improved genetic algorithmnot only has a strong search capability, but also thestability has been effectively improved.  相似文献
7.
In order to high reality and efficiency,the technique of motion capture (MoCap) has been widely used in the field of computer animation.With the development of motion capture,a large amount of motion capture databases are available and this is significant for the reuse of motion data.But due to the high degree of freedoms and high capture frequency,the dimension of the motion capture data is usually very high and this will lead to a low efficiency in data processing.So how to process the high dimension data and design an efficient and effective retrieval approach has become a challenge which we can’t ignore.In this paper,first we lay out some problems about the key techniques in motion capture data processing.Then the existing approaches are analyzed and summarized.At last,some future work is proposed.  相似文献
8.
Compactly supported radial basis function can enable the coefficient matrix of solving weigh linear system to have a sparse banded structure,thereby reducing the complexity of the algorithm.Firstly,based on the compactly supported radial basis function,the paper makes the complex quadratic function(Multiquadric,MQ for short) to be transformed and proposes a class of compactly supported MQ function.Secondly,the paper describes a method that interpolates discrete motion capture data to solve the motion vectors of the interpolation points and they are used in facial expression reconstruction.Finally,according to this characteristic of the uneven distribution of the face markers,the markers are numbered and grouped in accordance with the density level,and then be interpolated in line with each group.The approach not only ensures the accuracy of the deformation of face local area and smoothness,but also reduces the time complexity of computing.  相似文献
9.
针对复杂产品设计分解问题,如何提高分解效率,有效产生一些可行方案的问题,提出了一种智能化的矩阵分块算法。该算法结合两阶段分解法,引入模拟退火遗传算法,以设计关联矩阵的协调列数为目标函数,对矩阵内部的分块点组合进行优化求解,实现了设计关联矩阵的对角化分解。以提动式溢流阀的设计为例进行了验证,实验结果表明该算法能够快速产生有效解。  相似文献
10.
孙晓鹏  王冠  王璐  魏小鹏 《软件学报》2015,26(3):699-709
首先,对空间分布不均匀且无序的三维点云构造其二维主流形,并以与球面同胚的封闭曲面网格形式给出其二维主流形的二次优化逼近,以主流形网格有序均匀的结点分布表示三维点云空间分布无序且不均匀的形状特征,降低了三维形状描述的难度;然后,以基本几何变换作为快速粗对齐、以迭代最近法向点(ICNP)方法作为精准对齐,确定两个主曲面网格之间最佳刚性变换,ICNP方法在寻找最近点时考虑法向夹角,利用了更多的几何信息,实现快速精准的刚性对齐,兼顾计算精度和速度;最后,以对齐误差作为两个3D点云之间形状差异测度.实验结果表明:所提出的基于主流形二次曲面网格优化逼近的三维点云模型形状描述方法对三维点云的分辨率和噪声等干扰因素具有较高的健壮性,可以用于三维检索的形状描述.  相似文献
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