基于水平集方法的弱边界运动人体目标跟踪与轮廓提取

针对图像中目标和背景灰度偏差较小、目标边缘轮廓弱的特点,提出了一种快速收敛并具有较强捕获弱边缘能力的水平集曲线演化方法。该方法采用指数函数作为边缘指示函数,运用归一化的Gauss分布函数改进传统的正则化Dirac函数。在目标跟踪过程中,采用卡尔曼滤波获取视频相应帧图像的运动人体目标最小外接矩形框,对外接矩形框内运动人体进行水平集曲线演化,实现对人体目标的跟踪和轮廓提取。分别对可见光下的运动目标和红外运动视频序列进行仿真实验。结果表明,相对于传统方法,其在跟踪速度上有很大的提高,对于红外图像中的弱边界目标及凸凹度较大的区域,也具有快速准确的收敛效果。     

A new method for representing and matching shapes of natural objects

A new method for the representation and comparison of irregular two-dimensional shapes is presented. This method uses a polar transformation of the contour points about the geometric centre of the object. The distinctive vertices of the shape are extracted and used as comparative parameters to minimize the difference of contour distance from the centre. Experiments are performed, more than 39 000 comparisons of database shapes, provided by Sebastian et al. (ICCV (2001) 755), are made and the results are compared to those obtained therein. In addition, 450 comparisons of leaf shape are made and leaves of very similar shape are accurately distinguished. The method is shown to be invariant to translation, rotation and scaling and highly accurate in shape distinction. The method shows more tolerance to scale variation than that of Sebastian et al. (ICCV (2001) 755) and is less computationally intense.     

Recognition of dynamic hand gestures

This paper is concerned with the problem of recognition of dynamic hand gestures. We have considered gestures which are sequences of distinct hand poses. In these gestures hand poses can undergo motion and discrete changes. However, continuous deformations of the hand shapes are not permitted. We have developed a recognition engine which can reliably recognize these gestures despite individual variations. The engine also has the ability to detect start and end of gesture sequences in an automated fashion. The recognition strategy uses a combination of static shape recognition (performed using contour discriminant analysis), Kalman filter based hand tracking and a HMM based temporal characterization scheme. The system is fairly robust to background clutter and uses skin color for static shape recognition and tracking. A real time implementation on standard hardware is developed. Experimental results establish the effectiveness of the approach.     

自然山区大气景观模拟显示方法初探

提出了一个模拟大气、云雾等自然环境的照明模型，对视线距离较大，视野开阔的自然景物造型，如山体造型，更具有真实感效果，可获得模拟云、雾等天气特征的三维地形风景图。实验效果令人满意，并具有简单实用之特点。     

图像轮廓提取的迭代收缩算法

本文提出一种提取二值图轮廓的迭代收缩算法，在快速提取图像轮廓的同时，保持轮廓封闭性，并保留轮廓间关系信息，算法用于人脸识别系统中取得了较好的实验效果。     

利用高分辨率遥感地图自动更新道路信息

本文提出了利用高分辨率遥感地图实现道路信息自动更新的系统。系统利用辅助数据——数字化地表模型结合彩色红外遥感图像，有效的实现分类；在随后的对象提取中，引进已有的GIS数据库优化了用于提取的Snakes算法。系统采用的先分类后提取的流程以及辅助数据的使用减少了干扰，也提高了系统的工作效率。     

Tool path generation for machining free-form pockets using Voronoi diagrams

Voronoi diagrams for closed shapes have many practical applications, ranging from numerical control machining to mesh generation. Curve offsetting based on Voronoi diagrams avoids the topological problems encountered in the traditional offsetting algorithms. In this paper, we propose a procedure using Voronoi diagram-based tool-path generation for machining pockets with free-form boundaries. A pocket can be bounded by 2D free-form curve elements that are differentiable twice. The procedure consists of three steps:

Scale independent surface characterisation: Geography meets precision surface metrology

The recently published standard ISO 25178-2 distinguishes between field parameters and feature parameters for surface texture characterisation, whereby the main difference between these two types is due to the fact that the parameters belonging to the first group are deduced from all points of a scale-limited surface, while the parameters belonging to the second group are deduced from only a subset of predefined topological surface features. As specified in ISO 25178-2, two prerequisites are indispensable for the determination of the feature parameters, viz., an adequate data structure for surface characterisation and a suitable formal method for surface generalisation, i.e. for the successive elimination of the less important surface features. Within ISO 25178-2 change trees are proposed for describing the surface topography, while Wolf pruning is suggested for surface simplification (cf. also ISO 16610-85). Apart from the techniques specified in ISO 25178-2 and ISO 16610-85, the present paper describes a second geometrical–topological approach for the characterisation and generalisation of surfaces that has its origin within the geosciences and is based on weighted surface networks and w-contractions. In addition, it is revealed how the two approaches, both of which have their foundations in graph theory, are interrelated to each other and how, from a historical point of view, the GIScience approach forms the basis of the one applied within surface metrology. Finally, some applications within precision engineering are described.     

棒料弯曲形状自动测量研究

本文基于非接触测量方式,提出采用二维线轮廓传感器,全程自动扫描棒料轮廓,利用最小二乘法对截面中心进行拟合,由连续的截面中心确定棒料中心线,实现了棒料弯曲量计算以及弯曲形状的确定算法,为棒料自动校直工艺参数的计算奠定了基础。实验研究证明,这种测量方案不仅扫描速度快,稳定性好,而且对棒料的弯曲形状测量准确,满足自动校直工艺要求。