标题: 利用等位函数法结合形状资讯做影像序列的物体追踪
Object Tracking via the Level Set Method Integrated with Prior Shape
作者: 徐锦祥
陈稔
资讯科学与工程研究所
关键字: 等位函数法;形状;追踪;level set;shape prior;tracking;prior shape
公开日期: 2004
摘要: 物体追踪在电脑视觉、监测系统、交通监测站等,都有很大的应用,并且提供了高阶影像处理的前置工作。本论文提出一个对影像序列的物体轮廓线追踪方法。主要是结合物体形状资讯来改进Abdol-Reza Mansouri的方法。
在Abdol-Reza的方法中,追踪演算法主要是透过最小化一个由贝氏定理所推导出的能量函数,来变动所要用来追踪的轮廓线,使其往目标物逼进。此方法有三个优点。第一,不需要做物体运动估测。第二,物体允许任意变形,包括拓朴的改变。第三,物体的轮廓梯度不需要很大。而它所面临的缺点是,当物体的附近有跟其相近的背景时,追踪的结果将会受到很大的影响。我们希望透过结合物体的形状资讯来改进这个缺点。当被追踪物体有部分跟背景相似时,明确的部分由原来的方法追踪,并将其结果与形状资讯对齐,接着由形状资讯将不明确的部分补足。如果物体本身就整个能与背景分开时,形状资讯的权重将会自动被付予很小的值,以保有物体允许随意变形的特性。这样的整合方式,也将使我们的方法更具有弹性。
Detecting and tracking moving objects has a wide variety of applications in computer vision such as computer vision, video surveillance, traffic monitoring, etc. Additionally, it provides input to higher level vision tasks. This thesis presents an approach to tracking a moving object over a sequence of images. In particular, we improve the Abdol-Reza’s model by coupling with shape prior knowledge for shape perseverance in case of ambiguity.
In the model of Abdol-Reza, tracking is achieved by evolving the contour from frame to frame by minimizing an energy functional evaluated by Bayesian theory. There are three two favorable features in this model. First, no motion field or parameters needed to be computed. Second, deformable shapes of the object are allowed and the topology of the boundary is not constrained. Third, no assumption is made on the strength of the edge gradient. However, it also suffers from the constraints imposed on a degree of dissimilarity between the object and the background. A background region similar to the object might corrupt the contour evolution. We want to overcome this drawback by coupling with a shape prior in the associated energy functional. When the object is partially involved in a similar background, the original tracking term in the functional will dominate the result in the unambiguous background part, and the prior shape will guide the object movement in the ambiguous part. If the object is entirely distinguishable from the background, the weight of the shape prior is set low and thus allowing free deformation of the object. Compared to other tracking methods embedded with shape priors, the presented approach is more flexible, retaining the advantage of suffering little constraints on the deformable shape of the tracked object in many cases.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT009217619
http://hdl.handle.net/11536/74246
显示于类别:Thesis


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