基于特征分析的工程图智能识别算法

提出了一种基于图线和行程段特征分析,由行程段直接拾取整条图线的工程图识别算法。该算法不经过图段分别,根据整条图线的信息确定交点;通过分析线索、间隔等的规律确定线型。最后,基于工程图知识进行图线校正。该算法已付诸实践并取得良好效果。     

工程图矢量化中图文分离的一种快速算法

工程图纸通常是由图形和文字符合两部分组成，由于在矢量化中对图形和文字进一步处理的要求不同，故在矢量化之前把工程图中的图形和文字符号区分开来是十分重要的。本文提出了一种工程图矢量化图文分离算法，它能有效地将图形和文字分开，这种算法不仅可以减少多余的数据量，加快后期的线条提取速度，而且可使数据的关系更为清晰明了，分离出来的符号文件保留了其原来在图纸中的位置，为文字符号的识别或重新写入提供了方便。     

供配电CAD工程图中文本和数据的智能识别与匹配

介绍了一种智能识别算法,通过VB(VBA)语言,实现对工程图中的图形数据和各种标称数据智能识别提取,并与Excel电子表格或数据库进行数据交换,最终实现,智能生成电缆清册等报表。     

基于矢量化的二值工程图符号提取算法

工程图符号提取是工程图识别的重要步骤 .文中提出一种矢量化算法 ,该算法可以将工程图转换成图的表示法 .在该矢量化算法的基础上 ,又提出一种符号提取算法 ,这种算法可以有效地提取各种孤立和粘连符号     

工程图矢量化中的尺寸识别与重建

尺寸识别是工程图识别的重要环节。针对现有单人口识别算法的局限性，提出了一种多人口的尺寸识别算法，从多种已识别的图形元素开始搜索一个尺寸标识。在遇到不能正常识别的图形元素时，通过先搜索其他组成元素获得尺寸标识的初步确认后，放宽阈值对未识别元素进行再识别，有效地识别受退化或干扰影响较大的尺寸元素。提出了基于坐标网络的图形元素尺寸重建方法，通过建立坐标网使每一尺寸在整体环境下得到调整，满足了图低复用对图形数据精确度的要求。     

基于图纸理解的图形参数驱动的研究

针对工程图扫描输入识别后的特点,对基于图纸理解的图形参数化方法进行了探讨,提出了基于视图轴向尺寸链算法和尺寸派生策略,并在图形理解的基础上,用一般算法的几何推理方式实现了识别图形的参数驱动。     

面向内容的工程图识别与理解综述

对工程图识别与理解研究现状进行深入和系统的综述。工程图识别与理解 的核心在于利用知识表示、图形匹配、符号识别、几何推理、语义提取等技术,自动获取工 程图中各种显式描述（如几何图元、工程符号、工程对象等）及隐式信息（如设计语义等）。 分别对工程图矢量化、工程符号识别及工程对象识别进行了系统分析。在此基础上对工程图 识别性能评测、基准库等进行总结。最后对现有研究的难点及进一步研究方向进行了展望。     

工程图字符串提取算法

文字识别是扫描工程图矢量化的重要内容之一。由于工程图中文字信息具有多字体、多方向及由多种原因造成扫描工程图中噪音、缺损、字线粘连、字字粘连等特点 ,使文字识别变得非常困难。本文介绍了充分利用构图信息的字符串提取算法。可较好地增强文字的识别能力。     

基于改进的BP网的图形符号识别

提出了一种改进的 BP人工神经网络的图形识别算法 ,以达到加快识别过程和收敛速度的目的 ,可有效地处理断线、模糊图线、字线粘连等多种退化图纸的情况 ,既可获得线的逼近 ,又使识别具有自学习与自适应的智能性。     

基于双层结构的矢量工程图符号识别算法

为了从矢量工程图中自动提取零件种类和个数等信息,提出一种矢量工程图符号识别算法.首先定义矢量工程图中每个元素的3种共同抽象属性以及2个元素之间的关系描述子;然后提出描述符号的双层结构,其比传统的网状或树状结构简单;最后,通过关系描述子的匹配与双层结构的构造进行符号识别.另外,该算法利用四叉树、一次识别多种符号以及对关系描述子进行排序的方法加速符号识别.实验结果表明,文中算法比已有算法识别的符号种类更多,识别效率更高,而且在旋转和缩放变换条件下更加鲁棒.     

一种二维工程图向三维模型的尺寸映射算法

针对当前制造型企业内部存在二维工程图和三维CAD模型之间的数据共享问题,提出一种基于图匹配的二维工程图向三维CAD模型的尺寸映射算法,将二维工程图中的尺寸信息直接映射到对应的三维CAD模型上。首先将三维模型进行投影得到投影视图,然后将投影视图和二维工程图转化为一种空间关系图,对两个空间关系图进行图匹配,找出图元间的映射关系,并且利用工程图中尺寸标注的特点对算法进行改进,提高算法效率和可靠性。实验结果表明,该算法可以很好的实现二维工程图向三维CAD模型的尺寸映射。     

3D reconstruction of polyhedral objects from single parallel projections using cubic corner

This paper presents a direct method to recover the geometry of the 3D polyhedron depicted in a single parallel projection. It uses two sets of information, the list of faces in the object, obtained automatically from the drawing, and a user-identified cubic corner, to compute for the coordinates of the vertices in the drawing and thus establish the 3D geometry of the whole polyhedron. The algorithm exploits the topological structure of the polyhedron, implicit in the connectivities between the faces, resulting in a complexity that is linear in the number of faces. The method is extended to objects with no cubic corners as well. The algorithm works well for recovering objects from accurate line drawings, producing accurate 3D objects. A simple extension to the algorithm allows it to handle inaccurate drawings such as sketches, and produce 3D objects that are consistent with our human perception of the drawings.     

Recovering solid geometric object from single line drawing image

Many educational materials contain a lot of solid geometric figures. The solid geometric objects in these figures are usually drawn as 2D line drawings thus have lost their 3D information. This paper presents a method to recover the 3D information of the solid geometric object from single line drawing image taken from the geometric books, which would be used to help the users better present and understand the solid geometric object on their mobile devices. The main advantage of our method is the abilitYTo handle inaccurately processed sketches as opposed to the previous methods which require perfect line drawings as inputs. Our method consists of three main steps as follows. First, the sketch of the input line drawing image is automatically extracted and further represented as an undirected graph. Second, candidate 3D models from the pre-built 3D model database are found by graph similarity-based searching and sub-graph isomorphism matching. Third, for each candidate 3D model, the model parameters, the rotation and the translation aligning the model with the sketch are found by minimizing an objective function which is composed of the residuals between the vertices of the sketch and the 2D projections of the candidate model’s vertices, and an optimal reconstruction solution is further selected as the final result. Extensive experimental results demonstrate the effectiveness and robustness of our method for recovering the solid geometric object from single line drawing image.     

工程图数字水印技术研究

该文在分析工程图数字水印特点的基础上,采用微小扰动法,在工程图的编码冗余信息中嵌入水印。详细讨论了工程图中直线段、圆弧和圆的水印嵌入算法和水印检测算法,由于扰动量很小,因而不会被人感知,也不影响工程图的功能。随后,从理论和实例上分析了算法对平移、旋转、缩放、增加、删除等的抗攻击能力。     

Evaluating esthetics for user-sketched layouts of clustered graphs with known clustering information

This paper aims to empirically analyze the esthetics for user-sketched layouts of clustered graphs with known clustering information. In our experiments, given not only the adjacency list of a clustered graph but also its predefined clustering information, each participant was asked to manually sketch clustered graphs “nicely” from scratch on a tablet system using a stylus. Different from previous works, the main concern in this paper is on which graph drawing esthetics people favor when sketching their own drawings of clustered graphs with known clustering information. Another concern of this paper is on the esthetics of clustered graph layouts employed by participants which include not only characteristics and structures of the final graph layouts but also the behavior of user's sketching process (including layout creation and adjustment). By observing all layouts and drawing processes, the drawing strategies which participants applied and the drawing esthetics are analyzed. Results show that most participants were unsurprisingly able to draw graphs with clear presence of bridge edges and clustering cohesiveness; more importantly, to distinguish clusters within the restricted-size tablet screen during the drawing process, some of the participants were still able to make each cluster with fewer edge crossings, more symmetries, and more alignment of grid in a smaller drawing area where the cluster spreads. Our results support that to alleviate user's complex drawing tasks, aside from the grid-based editing function suggested by the previous work, graph drawing systems should also provide the clustering information if the structure of the graph to be drawn is known.     

Orthogonal drawings and crossing numbers of the Kronecker product of two cycles

An orthogonal drawing of a graph is an embedding of the graph in the plane such that each edge is representable as a chain of alternately horizontal and vertical line segments. This style of drawing finds applications in areas such as optoelectronic systems, information visualization and VLSI circuits. We present orthogonal drawings of the Kronecker product of two cycles around vertex partitions of the graph into grids. In the process, we derive upper bounds on the crossing number of the graph. The resulting upper bounds are within a constant multiple of the lower bounds. Unlike the Cartesian product that is amenable to an inductive treatment, the Kronecker product entails a case-to-case analysis since the results depend heavily on the parameters corresponding to the lengths of the two cycles.     

引黄工程计算机监控系统中的数据通信规约

介绍了引黄工程WAN结构和配置,提出了引黄工程计算机监控系统中数据通信的分层分布式结构模式,其通信协议采用TCP/IP协议,传输层的数据格式为DNP3.0,现地层采用现场总线和RS LINK通信协议。这些协议的开放性以及现地协议的实时性,既满足了引黄工程后期建设对计算机监控系统开放和可扩充的要求,又实现了全线自动调度调节以及现地实时控制的功能。     

基于改进的NRLCC编码的立体线图匹配算法

线图匹配在计算机视觉领域有着广泛的应用。该文研究基于改进的NRLCC编码以及面之间的关系进行立体线图的匹配。首先利用图同构检测目标线图与模型线图的面的排列关系是否一致;然后获取面的NRLCC编码和ENRLCC编码,分别得到面的顶点的凹凸性信息和组成面的曲线段的凹凸性信息。最后,利用以上几组信息,进行线图的匹配。试验结果表明,该方法可以对具有曲线边缘的工业物体进行准确的识别。     

Graph-based method for face identification from a single 2D linedrawing

The faces in a 2D fine drawing of an object provide important information for the reconstruction of its 3D geometry. In this paper, a graph-based optimization method is proposed for identifying the faces is a line drawing. The face identification is formulated as a maximum weight clique problem. This formulation is proven to be equivalent to the formulation proposed by Shpitalni and Upson (1996). The advantage of our formulation is that it enables one to develop a much faster algorithm to find the faces in a drawing. The significant improvement in speed is derived from two algorithms provided: the depth-first graph search for quickly generating possible faces from a drawing; and the maximum weight clique finding for obtaining the optimal face configurations of the drawing. The experimental results shown that our algorithm generates the same results of face identification as Shpitalni and Lipson's method, but is much faster when dealing with objects of more than 20 faces