基于主动轮廓线模型的海面运动目标跟踪

将主动轮廓线模型用于海面运动船只的跟踪，提出了一种自动选择主动轮廓线初始控制点的方法，增强了主动轮廓线模型的实用性：并将基于主动轮廓线模型的跟踪方法用于多个海面运动目标的跟踪。实验结果表明，提出的初始主动轮廓线自动选取方法可以准确地选择目标的轮廓线的特征点；基于主动轮廓线模型的跟踪方法可以比较准确地跟踪运动船只的主要轮廓特征。     

一种新的主动轮廓线跟踪算法

主动轮廓线模型,又称"蛇",由Kass等于1987年首次提出后在数字图像分析和计算机视觉等领域正在得到越来越广泛的应用.不过,现有的主动轮廓线搜索与跟踪算法存在许多问题.本文提出一种新的主动轮廓线跟踪算法--new_snake算法.它不但继承了已有算法的优点,而且克服了它们的主要缺点.它具有下列特点:算法快速收敛;控制点的数目自适应地改变,保证稳定跟踪;将硬强制力直接引入能量公式;可以方便地添加色彩信息约束;削弱了各参数的改变对算法的影响.大量实验验证了该算法的鲁棒性和实用性.     

基于PSO和M-S模型的图像分割方法

为得到快速、准确的图像分割方法，提出了一种基于微粒群算法（PSO）的主动轮廓线模型和Mumford-Shah（M-S）模型的方法。利用PSO方法对主动轮廓线模型的蛇点寻优，使其快速收敛到图像边缘附近，得到目标的粗糙轮廓，作为M-S模型的初始水平集；并将窄带方法引入M-S模型的计算，快速得到准确的分割结果。该方法克服了主动轮廓线模型对初始曲线敏感、不能收敛到物体的凹陷边缘、对噪声敏感问题和M-S模型需要对所有图像数据进行计算且计算量大等问题。实验结果表明了该方法的可行性和有效性。     

基于图像放大影响的多模板相关跟踪算法

目标实时跟踪算法是图像处理技术中的一个非常重要的应用，该算法将提供的原始目标怍为基准图像进行序列跟踪。实时跟踪算法有很多种，大多是基于图像匹配算法的跟踪方法，其中比较常用的为单模板相关跟踪。该文通过对图像放大对相关跟踪影响的分析，计算了单模板相关跟踪的最小图像放大率。针对单模板存在的问题提出了多模板跟踪算法，根据目标莉背景的位置分布提出了五模板相关跟踪，并给出了多模板跟踪算法中的相关结果置信度的计算方法，同时根据最终的相关位置给出了跟踪点的计算方法，仿真试验证明优于单模板跟踪算法。     

基于A^＊搜索方法的主动轮廓提取算法

在主动轮廓模型Snake的研究与应用中，如何降低Snake对初始轮廓的敏感性以厦如何保证能量极小化过程收敛到全局最小值，是两个极其重要的问题。为提取两点间的目标轮廓线，本文提出了基于A^＊搜索过程的Snake算法，将Snake能量极小化问题转换成势能地图的最短路径搜索问题。实验结果表明，该算法简化了Snake的初始化过程，而且Snaake能量收敛至全局最小值，具有良好的实用性与鲁棒性。     

一种改进的快速轮廓线提取算法

文章针对传统主动轮廓模型对噪声敏感,初始位置敏感和收敛速度慢等不足,提出了一种基于PSO和GVF的快速轮廓线提取算法。首先利用PSO对轮廓控制点进行寻优,使之快速地收敛到图像的边缘附近;然后利用插值算法,得到目标图像的较粗糙轮廓,以此目标轮廓作为下一步GVF收敛的初始位置,最后得到准确的轮廓线。实验结果表明该算法不仅能对图像轮廓线进行准确的提取,而且具有一定的抗噪性能,易于实现,速度快等特点。     

GVF Snake模型中初始轮廓线设置算法的研究

在详细分析了动态轮廓模型抗干扰性差、运算量大、不能逼近比较复杂轮廓、初始轮廓线设置复杂等问题原因的基础上,提出了轮廓线"有效逼近域"概念,进一步研究发现,这些问题都可以通过设置初始轮廓线到"有效逼近域"内,并有效地控制"有效逼近域"范围而得以解决。由于初始轮廓线只要求设置在"有效逼近域"内,因此符合基于小波变换多尺度边缘检测算法的特性,"有效逼近域"也可以通过控制GVF力场迭代次数来有效控制其大小。基于此,通过采用小波变换多尺度边缘检测获得不同分辨率边缘点,合理控制GVF力场迭代次数,提出初始轮廓线连接算法,成功地实现了初始轮廓线的有效设置。实验结果表明,能够准确地将初始轮廓线设置在"有效逼近域"内,并且"有效逼近域"的大小可以减小到真实轮廓左右5个像素以内,运算量有效的减小,抗干扰性也得到了很大的提高。     

基于改进的主动轮廓模型及光流估计的标记线跟踪

在心脏核磁共振图像分析中，标记线的跟踪是心肌运动分析及3维运动重建的重要步骤。为了提高心脏标记线跟踪的准确性，首先使用改进的基于动力学方程的主动轮廓模型来对标记线进行跟踪，并根据标记线的特点，引入了3种弹性势能，然后采用了新的内能函数，并使用新的方法来产生图像势能，由于改变了原模型中轮廓线初始速度为零的假设，并引入了光流估计作为轮廓的初始速度，从而提高了跟踪结果的准确性。对多序列心脏收缩期核磁共振图像的实验结果表明，该算法可以获得较好的跟踪效果。     

一种改进的多尺度梯度矢量流模型

梯度矢量流主动轮廓线模型是广泛应用于数字图像处理的一种目标轮廓跟踪算法,但易受干扰噪声及虚假边缘的影响,在结合多尺度图像分析的基础上,利用改进的梯度矢量流场,提出了一种改进的主动轮廓线模型。实验表明,该方法较好的限制了非目标边缘和噪声干扰的影响,提高了模型分割的精确性,具有较好的分割效果。     

基于孪生网络的单目标跟踪算法综述

单目标跟踪是计算机视觉领域的一个重要研究方向，在视频监控、自动驾驶等领域应用广泛。对于单目标跟踪算法，尽管已有大量总结研究，但大多基于相关滤波或深度学习。近年来，基于孪生网络的跟踪算法因在精度和速度之间取得的平衡受到研究者们的广泛关注，然而目前对该类型算法的总结分析相对较少，并且对这些算法的架构层面缺少系统分析。为深入了解基于孪生网络的单目标跟踪算法，对大量相关文献进行了总结与分析。首先阐述孪生网络的结构和应用，并根据孪生跟踪算法架构组成的分类介绍了各跟踪算法；然后列举单目标跟踪领域常用的数据集和评价指标，对25个主流跟踪算法在OTB2015数据集上分别进行整体和各属性的性能比较与分析，并列出23个孪生跟踪算法在LaSOT和GOT-10K测试集上的性能以及推理时的速度；最后对基于孪生网络的目标跟踪算法的研究进行总结，并对未来的发展方向进行展望。     

Coarse-to-fine segmentation and tracking using Sobolev active contours

Recently proposed Sobolev active contours introduced a new paradigm for minimizing energies defined on curves by changing the traditional cost of perturbing a curve and thereby redefining their gradients. Sobolev active contours evolve more globally and are less attracted to certain intermediate local minima than traditional active contours, and it is based on a well-structured Riemannian metric. In this paper, we analyze Sobolev active contours using scale-space analysis in order to understand their evolution across different scales. This analysis shows an extremely important and useful behavior of Sobolev contours, namely, that they move successively from coarse to increasingly finer scale motions in a continuous manner. This property illustrates that one justification for using the Sobolev technique is for applications where coarse-scale deformations are preferred over fine scale deformations. Along with other properties to be discussed, the coarse-to-fine observation reveals that Sobolev active contours are, in particular, ideally suited for tracking algorithms that use active contours. We will also justify our assertion that the Sobolev metric should be used over the traditional metric for active contours in tracking problems by experimentally showing how a variety of active contour based tracking methods can be significantly improved merely by evolving the active contour according to the Sobolev method.     

Tracking Deformable Templates Using a Shortest Path Algorithm

This paper proposes a new technique to track deformable templates. We extend the typical graph algorithms that have been used for active contour recovery to incorporate shape information. The advantage of graph algorithms is that they are guaranteed to find the global minimum of the energy function. The difficulty with their traditional use for active contours is that they consider only two pixels at a time when recovering the contour, making it impossible to enforce shape constraints. We define the deformable template as a polygonal contour, demonstrate the proper mapping between the image, the contour, and a graph, and show how to apply Dijkstra's algorithm to track contours in image sequences. Examples are shown for deforming contours, articulated objects, and smooth contours being tracked in simple and complicated backgrounds. We also provide an analysis of the computational requirements.     

Lip contour segmentation and tracking compliant with lip-reading application constraints

We propose to use both active contours and parametric models for lip contour extraction and tracking. In the first image, jumping snakes are used to detect outer and inner contour key points. These points initialize a lip parametric model composed of several cubic curves that are appropriate to the mouth deformations. According to a combined luminance and chrominance gradient, the initial model is optimized and precisely locked onto the lip contours. On subsequent images, the segmentation is based on the mouth bounding box and key point tracking. Quantitative and qualitative evaluations show the effectiveness of the algorithm for lip-reading applications.     

The Velocity Snake: Deformable Contour for Tracking in Spatio-Velocity Space

We present a new active contour model for boundary tracking and position prediction of nonrigid objects, which results from applying a velocity control to the class of elastodynamical contour models, known as snakes. The proposed control term minimizes an energy dissipation function which measures the difference between the contour velocity and the apparent velocity of the image. Treating the image video-sequence as continuous measurements along time, it is shown that the proposed control results in robust tracking. This is in contrast to the original snake model which is proven to have tracking errors relative to image (object) velocity, thus resulting in high sensitivity to image clutter. The motion estimation further allows for position prediction of nonrigid boundaries. Based on the proposed control approach, we propose a new class of real time tracking contours, varying from models with batch-mode control estimation to models with real time adaptive controllers.     

基于自适应符号函数的主动轮廓模型

几何主动轮廓模型的缺点是对初始轮廓位置特别敏感,基于距离规则水平集（DRLSE）模型的初始轮廓曲线必须设置在目标边界的内部或者外部.基于边缘的自适应水平集（ALSE）模型,提出了一种提高初始轮廓鲁棒性的方法.但两种模型均容易出现陷入虚假边界、从弱边缘处泄露以及抗噪声能力差等问题.设计了一个结合自适应符号函数和自适应边缘指示函数的模型,使得主动轮廓演化能根据自适应符号函数的方向从初始轮廓开始自动进行膨胀及收缩,很好地改善了水平集对初始轮廓敏感的缺点,提高了鲁棒性,同时解决了水平集对收敛速度慢以及易从弱边缘处泄露的问题.此外,为了使得模型演化更加稳定,提出了一个新的距离规则项.实验结果表明：自适应符号函数的主动轮廓模型不仅可以提高分割质量,缩短图像分割时间,同时提高了对初始轮廓的鲁棒性.     

基于二进小波变换的主动轮廓模型

针对传统的主动轮廓模型对噪声敏感的缺陷,在推广梯度矢量流的基础上,提出了基于二进小波变换的改进外力场的计算方法.通过综合利用图像小波分解的高频信息,迭代计算获得其外力场,使蛇在图像的多尺度空间中搜索目标轮廓.针对蛇模型对初始轮廓的依赖性问题,给出了在一维最大熵阈值分割后的图像上获取初始轮廓点的方法,减少了人工的干预,加快了蛇的收敛速度和效果.实验结果表明该模型能有效地排除噪声的干扰,搜索凹陷轮廓,而且对脆弱轮廓有很好的逼近能力.     

神经网络方法应用于轮廓定位

关于从图像中定位物体轮廓的问题,目前所采用的活动轮廓模型和基于自组织神经网络的算法,存在能量泛函优化容易陷入局部极值和演化过程依赖于初始轮廓的选取等问题。提出了一种基于RBF神经网络的轮廓定位算法。首先,通过自适应梯度阈值方法来获取图像特征点。然后,通过特征点的聚类建立一组基函数,把图像像素点的像素值和梯度构造输入向量空间,在网络权值训练完成后,利用网络的预测功能来准确判断物体轮廓。与传统算法相比,仿真结果表明提出的轮廓定位算法可以高效地实现目标轮廓定位。     

Dynamic programming for detecting, tracking, and matchingdeformable contours

The problem of segmenting an image into separate regions and tracking them over time is one of the most significant problems in vision. Terzopoulos et al. (1987) proposed an approach to detect the contour regions of complex shapes, assuming a user selected initial contour not very far from the desired solution. We propose to further explore the information provided by the user's selected points and apply an optimal method to detect contours which allows a segmentation of the image. The method is based on dynamic programming (DP), and applies to a wide variety of shapes. It is exact and not iterative. We also consider a multiscale approach capable of speeding up the algorithm by a factor of 20, although at the expense of losing the guaranteed optimality characteristic. The problem of tracking and matching these contours is addressed. For tracking, the final contour obtained at one frame is sampled and used as initial points for the next frame. Then, the same DP process is applied. For matching, a novel strategy is proposed where the solution is a smooth displacement field in which unmatched regions are allowed while cross vectors are not. The algorithm is again based on DP and the optimal solution is guaranteed. We have demonstrated the algorithms on natural objects in a large spectrum of applications, including interactive segmentation and automatic tracking of the regions of interest in medical images     

视频图像活动轮廓目标检测跟踪研究

研究视频图像目标跟踪定位精确度问题。由于在图像中通常会发生缩放,造成图像目标模糊不清。传统的目标跟踪算法该类算法仅以目标发生平移运动为假设前提,图像质量差。为解决上述问题,提出了一种活动轮廓目标跟踪定位检测算法。首先选择合适的滑窗,采用减背景法来确定视频对象的运动区域,采用卡尔曼形态滤波来消除残余的噪声,然后针对目标在活动轮廓局部内具有较高灰度值的特征,通过自适应阈值来判别滑窗中心位置是否存在目标。当滑窗遍历整幅图像后,就可以得到目标的定位结果。仿真结果表明,改进算法不仅能够消除差分图像中的显露背景,从而得到运动视频对象精确的轮廓,并且可进行多目标的分割与跟踪,具有一定的实际应用价值。     

A Bayesian approach to dynamic contours through stochastic samplingand simulated annealing

In many applications of image analysis, simply connected objects are to be located in noisy images. During the last 5-6 years active contour models have become popular for finding the contours of such objects. Connected to these models are iterative algorithms for finding the minimizing energy curves making the curves behave dynamically through the iterations. These approaches do however have several disadvantages. The numerical algorithms that are in use constrain the models that can be used. Furthermore, in many cases only local minima can be achieved. In this paper, the author discusses a method for curve detection based on a fully Bayesian approach. A model for image contours which allows the number of nodes on the contours to vary is introduced. Iterative algorithms based on stochastic sampling is constructed, which make it possible to simulate samples from the posterior distribution, making estimates and uncertainty measures of specific quantities available. Further, simulated annealing schemes making the curve move dynamically towards the global minimum energy configuration are presented. In theory, no restrictions on the models are made. In practice, however, computational aspects must be taken into consideration when choosing the models. Much more general models than the one used for active contours may however be applied. The approach is applied to ultrasound images of the left ventricle and to magnetic resonance images of the human brain, and show promising results