采用交互式缝合设置的三维服装模拟技术

目前, 国内外对于三维服装试衣技术的研究已逐渐深入, 但对于其中的关键步骤——服装衣片缝合信息的设置, 却少有成果. 服装的三维效果是通过缝合位于人体前后的二维衣片产生的, 精确及便捷的缝合设置是实现良好模拟效果的重要步骤之一. 在研究现有的三维虚拟试衣技术的基础上, 提出了缝合信息设定的方法流程, 并实现了交互式缝合设置过程. 在导入二维CAD衣片文件后, 经过交互式设置设定各衣片间的对应缝合边, 并以文件形式保存相关信息, 在试衣阶段通过导入该信息在对应衣片网格顶点间施加缝合力. 经实验, 通过该方法     

基于细分曲面的三维服装柔性实体模拟

提出一种基于细分曲面的三维服装柔性实体模拟算法，该算法将整个模拟过程分为两个阶段：首先利用四点细分曲面造型方法生成三维服装刚性曲面，然后在刚性曲面基础上通过引入织物的物理模型来模拟三维服装柔性曲面，通过物理和几何模拟方法有机结合，算法有效解决了复杂衣片间的缝合问题，较大地提高了模拟的计算效率，同时，也提出了一种基于细分曲面层次数据结构的碰撞检测算法，有效提高了模拟速度，提出的算法已全部在所开发的三维虚拟服装试衣系统中得以实现，实验结果表明：该算法具有模拟效率高、交互性强和易于计算机实现等优点。     

基于衣片网格局部变形的服装多样性研究

针对服装建模过程中,需要反复修改衣片来获得令人满意的虚拟服装模型以及计算复杂度高的问题,提出一种基于多控制点的衣片网格局部变形方法.该方法首先建立衣片网格模型,然后利用OpenGL的选择模式移动服装关键点,进而得到边界控制点,利用控制点对衣片网格模型进行局部变形,最后对衣片建立受力模型,通过虚拟缝合、碰撞检测以及纹理映射建立三维服装模型,展现服装整体效果,得到多样的服装模型.实验结果表明,由于在算法中不需要重新网络化,故具有较低的计算代价,同时也使得到的服装模型更加多样化.     

三维服装原型衣片生成的宽松量模型

在基于虚拟人体三维服装衣片生成的过程中，一个非常关键的问题就是三维服装衣片与三维虚拟人体之间宽松量的确定。宽松量的分析和处理决定了服装造型、穿着美的效果以及人体舒适度。本文提出了一种描述虚拟三维人体与三维服装衣片之间空隙量的宽松量模型。     

基于弹簧质点模型的二维/三维映射算法*

提出了一种用于服装设计的二维/三维映射算法.该算法基于弹簧质点变形模型,服装裁剪片二维到三维映射及三维到二维映射可以在该模型中得到统一的实现.在服装裁剪片二维到三维的映射过程中,二维裁剪片被放置在人体模型附近的初始位置,在缝合力的作用下,裁剪片自动变形并缝合到人体模型上.在服装裁剪片三维到二维映射的过程中,三维裁剪片被初始映射到指定的平面内,在弹性变形力的作用下,逐步变形并得到最终的二维裁剪片.在进行服装裁剪片二维到三维映射的过程中,考虑了干涉检验的问题.     

适于网络试穿的快速三维服装仿真方法

三维服装仿真技术是虚拟试衣的核心,目前三维服装仿真常用有限元技术来实现,该方法仿真花费的时间较长不能满足网络试衣的要求。提出了一种基于服装裁剪分片技术的三维服装仿真方法,该方法参考服装设计知识将待仿真服装划分为若干衣片,然后用贝塞尔曲面分别模拟这些衣片,最后利用纹理映射技术把服装布料的图案映射到相应的衣片,得到服装三维仿真模型。实验表明利用该方法得到的三维服装模型能够把服装的基本试穿效果展示出来,而且所需的时间很短,可以满足在线试穿的要求。     

基于OpenGL的交互式三维建模仿真应用研究

针对目前三维建模领域的现状以及存在的一些问题,提出了基于OpenGL的交互式三维建模仿真技术。从工程应用的角度出发,主要论述了OpenGL的技术特点与工作原理、基于二维剖面图的三维模型仿真算法、模型交互剖切原理以及剖面图的圆滑处理技术。在此基础上设计并实现了基于OpenGL的三维模型仿真系统。     

基于二维衣片反求服装曲面方法研究

以服装立体裁剪所获得服装衣片结构线二维数据与人体模型特征线三维数据为基础,依据按已知条件构造可展面理论,研究在定长映射下服装衣片与服装曲面之间转换的几何学方法,进而实现服装曲面二维向三维的变换.     

Java3D技术在三维服装设计中的应用

随着服装工业的发展,三维服装CAD技术得到广泛的应用,通过三维人体测量建立人体三维数据模型,在虚拟的三维人体上进行交互式立体设计,最后完成二维平面服装衣片。大大提高了服装工业产品设计的水平和生产的效率。本文叙述了利用强大的Java3D技术进行三维显示和设计的基本原理和方法。     

基于光线投射采样和四元数正交矩的高效三维医学影像鲁棒零水印算法

针对三维医学影像的版权保护问题，以及随着待保护图像数量增加而导致的水印存储容量同步增加的问题，提出了一种基于光线投射采样和极复指数矩的三维医学影像鲁棒性零水印算法。首先，提出了一种基于光线投射的采样算法，对多张二维医学图像序列构成的三维医学影像进行特征采样并在二维图像空间中进行描述；其次，提出了一种针对三维医学影像的鲁棒性零水印算法，所提算法通过光线投射采样获取三维医学影像的冠状面、矢状面和横切面的3个二维特征图像，将3个二维特征图像进行极复指数变换获得四元数正交矩；最后，使用四元数正交矩和Logistic混沌加密构建零水印信息。仿真实验结果表明，在各种常见的图像处理攻击和几何攻击下所提算法能够保持零水印提取的比特正确率在0.920 0以上，水印存储容量随着三维医学影像的数据增多而提升，与其他优秀的二维医学图像零水印算法相比，所提算法的存储容量至少提升了93.75%。     

Image stitching using structure deformation

The aim of this paper is to achieve seamless image stitching without producing visual artifact caused by severe intensity discrepancy and structure misalignment, given that the input images are roughly aligned or globally registered. Our new approach is based on structure deformation and propagation for achieving overall consistency in image structure and intensity.The new stitching algorithm, which has found applications in image compositing, image blending, and intensity correction,consists of the following main processes. Depending on the compatibility and distinctiveness of the 2-D features detected in the image plane, single or double optimal partitions are computed subject to the constraints of intensity coherence and structure continuity. Afterwards, specific 1-D features are detected along the computed optimal partitions, from which a set of sparse deformation vectors is derived to encode 1-D feature matching between the partitions. These sparse deformation cues are robustly propagated into the input images by solving the associated minimization problem in gradient domain, thus providing a uniform framework for the simultaneous alignment of image structure and intensity. We present results in general image compositing and blending, in order to show the effectiveness of our method in producing seamless stitching results from complex input images.     

Efficient Calculations of 3-D FFTs on Spiral Contours

This paper proposes a fast algorithm, called the SpiralFFT, that computes samples of the 3-D discrete Fourier transform of an object of interest along spiral contours in frequency space. This type of sampling geometry is prevalent in 3-D magnetic resonance imaging, as spiral sampling patterns allow for rapid, uninterrupted scanning over a large range of frequencies. We show that parameterizing the spiral contours in a certain way allows us to decompose the computation into a series of 1-D transforms, meaning that the 3-D transform is effectively separable, while still yielding spiral sampling patterns that are geometrically faithful and provide dense coverage of 3-D frequency space. We present a number of simulations which demonstrate that the SpiralFFT compares favorably to a state-of-the-art algorithm for computing general non-uniform discrete Fourier transforms.     

An augmented-reality-based real-time panoramic vision system for autonomous navigation

The paper discusses a panoramic vision system for autonomous-navigation purposes. It describes an economic PC-based method for integrating data from multiple camera sources in real time. The views from adjacent cameras are visualized together as a panorama of the scene using a modified correlation-based stitching algorithm. A separate operator is presented with a particular slice of the panorama matching the user's viewing direction. Additionally, a simulated environment is created where the operator can choose to augment the video by simultaneously viewing an artificial three-dimensional (3-D) view of the scene. Potential applications of this system include enhancing quality and range of visual cues, and navigation under hostile circumstances where direct view of the environment is not possible or desirable.     

基于ORB算法和OECF模型的快速图像拼接研究

为了增加移动机器人视觉导航中的成像范围,提出了一种基于ORB算法和OECF模型的图像拼接算法,获取的图像进行预处理后,先利用SIFT算法提取特征点,再用ORB算法获取特征点的二进制码串描述子进行匹配,而后通过投影变换模型获取参数,最后估计摄像机的光电转换函数OECF（Opto-Electronic Conversion Function）,利用Laguerre OECF模型参数对拼接图像进行色彩调整,解决了多幅图像拼接中颜色不一致的问题。实验结果表明,该算法能有效地对图像进行拼接,配准速度和拼接视觉效果和优于其他算法。     

The Effects of Stitching Orders in Patch-and-Stitch WSN Localization Algorithms

A "patch-and-stitch” localization algorithm divides the network into small overlapping subregions. Typically, each subregion consists of a node and all or some of its neighbors. For each subregion, the algorithm builds a local map, called a patch, which is actually an embedding of the nodes it spans in a relative coordinate system. Finally, the algorithm stitches those patches to form a single global map. In a patch-and-stitch algorithm, the stitching order makes an influence on both the performance and the complexity of the algorithm. In this paper, we present a formal framework to deal with stitching orders in patch-and-stitch localization algorithms. In our framework, the stitching order is determined by a stitching scheme and the stitching scheme consists of a stitching policy and a potential function. The potential function is to predict how well a patch will be stitched if patches are stitched according to a given partial order. The stitching policy is a mechanism that determines the stitching order based on the predictions by the potential function. We present various stitching schemes and evaluate them through simulations. In addition, we apply the patch-and-stitch strategy into the anchor-based localization and propose a clustering-based localization algorithm. A potential function is used to partition the network into clusters each of which is centered at an anchor node. For each cluster, a cluster map is constructed via the anchor-free localization algorithm. Then, those cluster maps are combined to form a single global map. We propose a stitching technique for combining those cluster maps and analyze the performance of the algorithm by simulations.     

Cutting and stitching: converting sets of polygons to manifoldsurfaces

Many real-world polygonal surfaces contain topological singularities that represent a challenge for processes such as simplification, compression, and smoothing. We present an algorithm that removes singularities from nonmanifold sets of polygons to create manifold (optionally oriented) polygonal surfaces. We identify singular vertices and edges, multiply singular vertices, and cut through singular edges. In an optional stitching operation, we maintain the surface as a manifold while joining boundary edges. We present two different edge stitching strategies, called pinching and snapping. Our algorithm manipulates the surface topology and ignores physical coordinates. Except for the optional stitching, the algorithm has a linear complexity and requires no floating point operations. In addition to introducing new algorithms, we expose the complexity (and pitfalls) associated with stitching. Finally, several real-world examples are studied     

一种新的基于柱面和特征的图像拼接算法

当要获取大场景图像时,由于摄像设备视角的限制,不可能一次拍出,这时需要拼接技术将多幅连续图像拼接出一幅大图像.但是对于在不同角度下拍摄的不在同一平面的图像,直接拼接会在重合区域发生局部扭曲现象,因此提出了一种基于柱面和特征的图像拼接算法.将不在同一投影平面的图像映射到柱面后,结合边缘信息和近似最近邻的优先搜索算法查找可能特征匹配对,最后实现拼接.实验结果表明,该算法拼接效果比较理想,鲁棒性强,具有较高的使用价值.     

基于块边缘特征直方图的图像检索

本文提出一种利用块边缘特征来进行图像检索的方法。首先对图像中每个8×8的块分别提取其决边缘特征,利用块边缘特征构建三维或四维直方图进行图像检索。所有数据在 DCT 压缩域中进行处理,从而降低了计算复杂度。实验结果表明,该方法与传统的基于 DCT 压缩域的图像检索方法相比,具有检索准确度高和检索速度快的特点。     

基于文字特征的文档碎纸片半自动拼接

分析了基于几何特征的碎纸片自动拼接方法的缺点,研究了碎纸片内文字行特征、表格特征特点,以及碎纸片内文字行特征、表格线特征的获取方法,提出了基于碎片文字行特征或表格特征的碎片半自动拼接算法。根据算法研制了C语言计算机程序,用该程序对一实际例子进行了拼接试验,试验结果表明该方法效果良好。     

局部特征及视觉一致性的柱面全景拼接算法

目的 传统的基于平面拼接算法生成的全景图像存在严重的失真问题,很难保证良好的视觉一致性;而普通柱面拼接算法无法较好地满足实时性要求。为此,提出一种基于改进SIFT（scale-invariant feature transform）特征描述子的柱面全景图像拼接算法。方法 首先将待拼接的图像序列进行柱面投影,利用改进的SIFT特征检测器获取图像中的特征点,生成64维SIFT特征描述子;然后根据特征描述子之间的欧氏距离提取初始特征点对,利用RANSAC（random sample consensus）方法进一步剔除伪匹配特征点对并建立待拼接图像之间的空间变换矩阵;最后根据图像之间的空间变换矩阵进行图像配准,采用加权平均融合的方法完成图像的无缝拼接。结果 本文全景图拼接算法,可以有效地克服平面拼接算法存在的失真问题,保证了全景图像的视觉一致性。同时,相比普通柱面拼接算法,本文算法的拼接速度提高了近一倍。结论 通过对不同尺寸和数量的图像序列构建全景图,相对于平面拼接算法和普通柱面拼接算法,本文算法可以有效实现图像之间的拼接,生成宽视野、高分辨率的全景图像,且能够应用于对实时性要求比较高的图像拼接场合。