基于活动轮廓模型的人脸特征提取方法的研究

人脸面部特征提取是自动视觉翻译和人脸识别中的最关键的技术之一。本文对活动轮廓模型理论的基本原理、方法和技术等作了有益的探索和尝试,并在此基础上,提出了提取人脸面部特征的系列算法,特征是精确的轮廓描述而非简单的数字表达,实验中,我们用动态模板方法提取眼睛轮廓,用活动轮廓方法提取眉毛形状,结果证明,该方法具有较强的鲁棒性和自适应性。     

多尺度空间的自动形状模型的构造算法

提出一种基于多尺度的轮廓模型自动构造算法，可归纳出有形变的物体的轮廓结构．对于噪声及形变程度差异较大的轮廓，首先用多尺度的方法将轮廓分段匹配，根据每段曲线上的噪声和形变程度选择合适的滤波尺度；然后对由轮廓匹配得到的曲线段的对应关系进行归纳调整，得到它们的通用结构模型．该算法适用于对一类具有相同结构但局部存在不同程度噪声和形变的闭合轮廓建立模型，将其用在行人轮廓的建模上取得了较好的效果．     

Parameterization-free active contour models with topology control

We present a novel approach for representing and evolving deformable active contours by restricting the movement of the contour vertices to the grid lines of a uniform lattice. This restriction implicitly controls the (re)parameterization of the contour and hence makes it possible to employ parameterization-independent evolution rules. Moreover, the underlying uniform grid makes self-collision detection very efficient. Our contour model is also able to perform topology changes, but – more importantly – it can detect and handle self-collisions at subpixel precision. In applications where topology changes are not appropriate, we generate contours that touch themselves without any gaps or self-intersections.     

Deformable model for estimating clothed and naked human shapes from a single image

Estimation of human shape from images has numerous applications ranging from graphics to surveillance. A single image provides insufficient constraints (e.g. clothing), making human shape estimation more challenging. We propose a method to simultaneously estimate a person’s clothed and naked shapes from a single image of that person wearing clothing. The key component of our method is a deformable model of clothed human shape. We learn our deformable model, which spans variations in pose, body, and clothes, from a training dataset. These variations are derived by the non-rigid surface deformation, and encoded in various low-dimension parameters. Our deformable model can be used to produce clothed 3D meshes for different people in different poses, which neither appears in the training dataset. Afterward, given an input image, our deformable model is initialized with a few user-specified 2D joints and contours of the person. We optimize the parameters of the deformable model by pose fitting and body fitting in an iterative way. Then the clothed and naked 3D shapes of the person can be obtained simultaneously. We illustrate our method for texture mapping and animation. The experimental results on real images demonstrate the effectiveness of our method.     

基于活动轮廓模型的高分辨率影像河道边界提取算法研究

河( 航) 道边界定位是河( 航) 道测量的重要内容, 对于内河航运交通、水利工程建设以及水资源开发利用等有着非常重要的意义。在目前遥感影像水体信息提取的研究基础上, 结合计算机视觉领域中的可变形模板轮廓匹配技术的优点, 同时考虑高分辨率影像上河道边界的光谱特征, 提出了一种基于活动轮廓模型的高分辨率影像河道边界提取算法。数据源选用四川宜宾地区的QuickBird影像, 采用本算法对初始轮廓进行变形, 匹配河道边界的真实位置。对于位于真实边界附近的初始轮廓, 拟合的边界线上落在距离真实边界两个像素内的点数达到70% , 5 个像素以内的点数达到90%以上。结果说明引入计算机视觉领域中比较成熟的技术将给高分辨率遥感影像的信息提取开辟新的途径。     

一种新的动态轮廓模型

动态轮廓模型是提取图象中物体轮廓的一种有效方法，提取图象中物体的轮廓在计算机视觉和模式识别中有很重要的意义。Ｋａｓｓ提出的能量最小化动态轮廓模型，称为Ｓｎａｋｅ，被证明是提取图象中凸形物体轮廓的有效方法。文中对Ｋａｓｓ的模型进行详细分析，指出它的局限性和不足之处，对它进行改进，提出一种新的动态轮廓模型，该模型不但能精确地提取图象中的凸形物体的轮廓，而且能提取一些凹形物体和多个物体的轮廓，在任何情况     

基于先验模型约束的Snake算法

提出了一种先验模型的方法,给活动轮廓模型设定了目标形状模板。在蛇点的运动过程中,利用归一化傅里叶描述子对蛇点轮廓和先验模型进行描述,反复比较蛇点和先验模型的差距,使蛇点轮廓的运动的形状逐渐逼近先验模型,更精确地收敛于目标物体轮廓。     

Vehicle segmentation and classification using deformable templates

This paper proposes a segmentation algorithm using deformable template models to segment a vehicle of interest both from the stationary complex background and other moving vehicles in an image sequence. We define a polygonal template to characterize a general model of a vehicle and derive a prior probability density function to constrain the template to be deformed within a set of allowed shapes. We propose a likelihood probability density function which combines motion information and edge directionality to ensure that the deformable template is contained within the moving areas in the image and its boundary coincides with strong edges with the same orientation in the image. The segmentation problem is reduced to a minimization problem and solved by the Metropolis algorithm. The system was successfully tested on 405 image sequences containing multiple moving vehicles on a highway     

基于图形硬件的光滑线条绘制(英文)

线条能够以相当少的可视信息来有效地表示一个三维模型的形状.利用图形硬件的高度并行处理能力,文中提出了一种新的基于物体空间的线条绘制方法.对于一个光滑物体形状,新型的Suggestive轮廓线能够结合侧影轮廓线来生成非常好的视点相关的线条效果.并且,最新被引入到Direet3D 10流水线的几何着色器能处理三角形图元数据及输出零个或多个线条图元.文中提出了一种并行化的线条绘制方法,能够直接在几何着色器中抽取三维的特征线条.该方法能根据视点与模型的距离自动地选取合适比例的线条进行绘制,绘制的线条平滑,绘制速度快.在文章最后给出的许多实验示例证实了该方法的效果.