借助游程运算实现多边形叠置分析

考虑到基于直接编码的栅格数据在计算效率和存储能力上的不足,提出一种便于代数操作的游程编码数据结构,以优化基于直接编码栅格数据的代数运算。介绍了基于该数据结构的游程“交”运算的实现方法,并在算法实现过程中完成游程属性的各种代数运算。提出使用这种游程的“交”运算完成多边形的叠置分析,其基本思路是：分别将两个图层中的多边形数据转换为游程集合,在栅格场中的任一行上使用叠加图的游程单元与底图上该行的游程集合执行“交”运算,逐行执行这种游程“交”运算得到两个图层之间多边形相交的结果游程集合,并根据“Union”、“Erase”等不同的叠置方式提取满足条件的游程单元,最后将游程矢量化为多边形数据输出。在叠置运算过程中,通过游程的“交”运算即能够实现图层间多边形的各种叠置方式,表明该运算具有很强的通用性。     

海量数据多边形布尔运算的区域分割算法

研究了一种大数据量的2维多边形,称为海量数据多边形,其边界由直线段和圆弧段组成,顶点很多,形状复杂。本文设计并实现了海量数据多边形之间的布尔运算算法。首先用区域划分的方法快速求解出两多边形的交点,然后判断各交点的出点、入点性质,最后沿着多边形的边界跟踪,并根据并、交、差的不同要求切换跟踪路线,直到形成封闭的回路。运算结果仍为2维多边形。该算法从实用的角度出发,避开繁琐的数学推理,易于程序实现,在实际应用中显著提高了布尔运算的效率。     

图形裁剪算法研究

本文介绍和研究直线、曲线和多边形的最新裁剪算法,包括作者近期的研究成果。首先对于矩形窗口,介绍了直线裁剪算法,圆和椭圆裁剪算法以及参数曲线的裁剪算法。然后,介绍了多边形窗口的直线裁剪算法和多边形窗口的多边形裁剪算法以及区域间的“交”、“差”和“并”操作。最后,介绍了圆形和椭圆形窗口的直线裁剪算法。     

三维网格模型的布尔运算方法

提出了一种基于三维网格模型的布尔运算方法。首先通过基于方向包围盒（OBB）层次包围盒树的碰撞检测算法,得到实体的相交三角形对;接下来求出两相交三角形之间的交线,建立与三角形的交线拓扑关系;通过分类处理三种交线类型来对相交三角形进行区域划分,得到一系列多边形,并对多边形进行三角剖分形成结果区域;最后根据体的包含关系构建关系邻接表,判断多边形区域的相对于其他实体的内外关系并通过网格模型的拓扑关系,定位表面三角网格区域;同时根据交、并、差等布尔操作,对结果区域进行取舍,得到最终结果。实验结果表明相交部分的岩性与实体的岩性相吻合,验证了该算法的正确性以及可行性。     

确定两个任意简单多边形交、并、差的算法

提出了把多边形的边分为奇偶边的新思想，根据输入多边形A，B之间边的拓扑关系，划分A，B边为内边、外边、重叠边3种，揭示A，B与它们的交、并、差之间边的本质联系，进而描述了确定任意两个简单多边形交、并、差算法．算法的时间复杂度为O((n m k)log(n m k))，其中n，m分别是A，B的顶点数，k是两多边形的交点数．算法建立在数学理论基础之上，很好地处理了布尔运算的奇异情形，比如重叠边，边与边相交于边的顶点等情形．本算法易于编程实现。     

一种基于网格的从明暗恢复形状方法

针对目前“从明暗恢复形状”时存在计算复杂及收敛性差等问题,提出一种基于网格的解决方法。首先通过图像预处理及区域划分操作将原始图像分割成多个亮度离散的多边形区域,并逐步转换成平面三角形网格,然后根据Lambert定律建立关于空间网格顶点坐标的方程组,在使用最小二乘法求解后,直接将结果应用到OpenGL或DirectX等实时渲染引擎的图形管道中,实现模型的建立与显示。经仿真实验证明该方法计算方便,可逼真重建原始物体的形状。     

用VC++实现的任意多边形裁剪算法

提出了一个用VC++语言实现的凸多边形、凹多边形,也可以是带内环的多边形的裁剪算法,可以求上述多边形的"交"、"并"以及"差".首先,该算法使用VC++支持的CObList类和CArray类的对象存储数据,具有占用内存空间少及处理速度快的特点;再通过算法和数据结构的设计不仅使得多边形顶点可按顺时针方向或逆时针方向输入,而且减少了求解过程中对多边形顶点数据的遍历次数;基于判断和计算交点是裁剪算法的主要工作,文中引入了求交前的预处理,避免了大量不必要的求交,降低了算法的时间复杂度.最为重要的是该算法不需要对两多边形的边重合或两多边形在顶点处相交的情况作特殊处理.     

直线剖分平面算法的实现和应用

本文引入一种称为“区域树”的二叉树结构来表示若干直线由于相交而形成的对平面的剖分,并以之实现了一个“增加构造”方式的直线剖分平面算法。算法可用于解决许多与平面直线图形有关的问题,本文给出了如下应用实例：点定位问题,半平面公共交问题,简单多边形凸分解问题,简单多边形求交问题。     

基于倾斜摄影的三维模型单体化方法研究

利用三角面片的可分割性质,解决倾斜摄影数据的三维模型可分离单体化问题。该方法首先绘制切割多边形,确定单体化模型边界,然后使用包围盒方法进行求交检测,获得需要切割的三角面片。之后计算求交检测所得三角面片与切割多边形的交点,然后详细分析切割多边形与三角面片相交时的不同相交情形,并针对不同的相交情形采用不同的切割方法。最后,对相交区域三角面片进行裁切并重构,再纹理重构并实现多细节分层后得到分离的单体化模型。实验结果表明,该方法可有效实现倾斜摄影三维模型的分离单体化。     

快速多边形区域三角化算法与实现 *

多边形区域三角化的基本思想是 :首先将简单多边形分解为多个单调多边形 ,然后对每个单调多边形进行三角化。快速多边形区域三角化算法先由多边形顶点的位置特征分为不同的类型 ,并沿指定方向对顶点进行排序 ,然后顺序取出各顶点 ,根据顶点类型 ,确定准单调多边形的产生、增长或结束 ,最后对所产生的多个单调多边形进行三角化。该算法充分利用多边形的顶点、边的拓扑关系 ,计算量少、实现简单 ,适用于带有洞、岛的任意简单多边形 ,速度较快。     

一种视频文本自动定位、跟踪和识别的方法

视频数据中的文本能提供重要的语义信息。本文提出了一种视频文本自动定位、跟踪和识别的方法，首先用基于小波和LH检测视频帧文本所在的位置，然后用运动估计的方法，跟踪后继帧文本的位置，再用多帧平均的方法增强文本区域，最后经过二值化处理和连通分量分析，将文本字符送入OCR软件进行识别。实验结果表明，该方法简单易行，能快速地定位和跟踪文本区域，定位精度和识别效果良好。     

Software congestion, mobile servers, and the hyperbolic model

The phenomenon of software congestion is examined. The term refers to situations in which the performance bottleneck of a system is an element of software, rather than a hardware device. Software congestion can occur in any system which contains one or more elements of software whose services may be simultaneously desired by multiple clients, but which can service only one client at a time. It is shown that the use of models which ignore software congestion can produce results that are completely irrelevant to actual system behavior. Furthermore, software congestion is frequently invisible to conventional performance measurement tools. A notational scheme, called mobile servers representation, is introduced for describing those systems in which software congestion may be important. An approximate analytical model, called the hyperbolic model, is developed for analyzing systems with software congestion     

Classification of Fault-Prone Software Modules: Prior Probabilities, Costs, and Model Evaluation

Software quality models can give timely predictions of reliability indicators, for targeting software improvement efforts. In some cases, classification techniques are sufficient for useful software quality models.The software engineering community has not applied informed prior probabilities widely to software quality classification modeling studies. Moreover, even though costs are of paramount concern to software managers, costs of misclassification have received little attention in the software engineering literature. This paper applies informed prior probabilities and costs of misclassification to software quality classification. We also discuss the advantages and limitations of several statistical methods for evaluating the accuracy of software quality classification models.We conducted two full-scale industrial case studies which integrated these concepts with nonparametric discriminant analysis to illustrate how they can be used by a classification technique. The case studies supported our hypothesis that classification models of software quality can benefit by considering informed prior probabilities and by minimizing the expected cost of misclassifications. The case studies also illustrated the advantages and limitations of resubstitution, cross-validation, and data splitting for model evaluation.     

Across disciplines: risk, design, method, process, and tools

In the search for solutions to make software development more predictable and controllable, one often looks for parallels in other disciplines such as architecture, bridge construction, and so on. The article looks at software development from the perspective of the electrical industry. Inspired by their management tradition, ATH techniek b.v. has learned to apply proven management techniques to software development. Simple and commonsense principles yield excellent results; for instance, developers reduced risk by estimating project effort using two different measures and by controlling execution. Comparing the software development processes with what goes on in the rest of the company or another application domain can be instructive     

Fighting Bugs: Remove, Retry, Replicate, and Rejuvenate

Even if software developers don't fully understand the faults or know their location in the code, software rejuvenation can help avoid failures in the presence of aging-related bugs. This is good news because reproducing and isolating an aging-related bug can be quite involved, similar to other Mandelbugs. Moreover, monitoring for signs of software aging can even help detect software faults that were missed during the development and testing phases. If, on the other hand, a developer can detect a specific aging-related bug in the code, fixing it and distributing a software update might be worthwhile. In the case of the Patriot missile-defense system, a modified version of the software was indeed prepared and deployed to users. It arrived at Dhahran on 26 February 1991- a day after the fatal incident     

化工原理实验数据处理软件的开发

本软件旨在解决通常的化工原理实验数据处理过程中或因计算复杂,或因作图时不可避免的出错而影响实验结果的问题.它以Visual Basic 6.0为开发工具,采用最小二乘法直线拟合、非线性拟合、数值积分等方法处理实验数据,可完全消除学生作图出错,使实验结果更正确、更科学.本软件为处理化工原理实验数据提供方便、快捷的方法,也为教师批改实验报告提供可靠的依据.该软件在中文Windows环境中运行,界面美观、操作方便.     

基于图形信息的HEVC帧间预测快速算法

由于最新的视频编码标准HEVC（high efficiency video coding）应用四叉树的递归结构进行编码单元的划分,使得帧间预测的过程极为复杂,编码的时间效率比较低下。针对HEVC帧间预测过程,提出了一种基于纹理信息和稳定区域检测的快速算法,旨在检测出相对平坦的区域和随时间变化较稳定的区域,来提前终止四叉树的编码单元的划分。这些平坦或者稳定的区域用较大的编码预测单元就能进行比较准确的运动估计和预测,不需要再进行更小编码预测单元的划分,因此HEVC编码器的时间复杂度大幅度降低。实验结果表明,改进后的算法编码时间平均节省了34%左右,并且造成的视频质量损失非常低,有0.038 dB的PSNR下降和0.56%的码率增加。     

Developer social networks in software engineering:construction,analysis,and applications

With the increasing popularity of Internet, more and more developers are collaborating together for software development. During the collaboration, a lot of information related to software development, including communication and coordination information of developers, can be recorded in software repositories. The information can be employed to construct Developer Social Networks （DSNs） for facilitating tasks in software engineering. In this paper, we survey recent advances of DSNs and examine three fundamental steps of DSNs, namely construction, analysis, and applications. We summarize the state-of-the-art methods in the three steps and investigate the relationships among them. Furthermore, we discuss the main issues and point out the future opportunities in the study of DSNs.     

Current accreditation, certification, and licensure activities related to software engineering

The issues associated with the accreditation, certification, and licensure of software engineers are, or at least should be, of great concern to the software engineering community. Perhaps as a result of publicity about safety-critical software disasters in the news media, some state legislatures have considered regulating the practice of software engineering, and some professionals believe that accreditation, certification, and licensure are inevitable. Yet there is no agreed-upon body of knowledge for software engineering on which to base accreditation, certification, or licensure, which makes implementing them difficult at best. In addition, it is not clear that these processes and possible mechanisms to support them are well understood within the software engineering community. This paper surveys how these three processes are conducted in other professions, summarizes the processes as they currently exist for computing in general, identifies some issues that are involved in implementing the processes for software engineering, and suggests possible actions that can be taken by the software engineering profession. The implications of accreditation, certification, and licensure for education are also discussed.