基于相似性学习的三维模型最优视图选择算法

针对已有最优视图度量难以适用于不同类型的三维模型,提出基于用户知识、在模型库中为各类模型建立最优视图样例,并在此基础上进行相似性学习,根据相似性度量获得输入模型最优视图的选择算法.首先采用AdaBoost算法对输入三维模型形状特征进行相似性学习,得到该模型的最优视图样例;然后将输入模型从不同视点得到的渲染视图和最优视图样例进行形状相似性分析,以相似度最高者作为输入模型的最优视图.实验结果表明,采用文中算法得到的最优视图不仅可以有效地逼近用户选择结果,而且具有较好的稳定性.     

基于协同过滤和标签的混合音乐推荐算法研究

结合音乐这一特定的推荐对象,针对传统单一的推荐算法不能有效解决音乐推荐中的准确度问题,提出一种协同过滤技术和标签相结合的音乐推荐算法。该算法先通过协同过滤技术确定相似用户,再通过相似用户对某一歌手的标签评分预测另一用户对该歌手的偏好程度,从而选择更符合用户喜好的音乐进行推荐,以此提升个性化推荐效率,为优化音乐推荐系统提供参考方法。     

一种防边权和语义攻击的位置隐私保护方法

边权攻击和位置语义攻击根据移动用户活动的周边环境推断用户的位置,泄露用户的位置隐私。针对该问题,提出一种防边权攻击的位置语义安全隐私保护方法。该方法将道路的敏感度和关联度结合,构建道路隐私度,描述道路在语义位置的敏感性,及道路与匿名集中其他道路上用户数量分布的均衡性;基于中心服务器结构,根据用户的位置隐私要求,采用宽度优先搜索方式,筛选道路隐私度最小的道路加入匿名集,以生成具备语义安全和防边权推断攻击的匿名集。仿真测试结果表明,该方法筛选的匿名集的匿名成功率达到87%,抗边权攻击和语义攻击的能力要高于对比算法。     

增强现实环境下的汽车A立柱视野评估方法

针对目前汽车造型设计过程中A立柱视野评估缺乏从设计师视角主动参与的使能工具,提出基于增强现实技术的汽车A立柱评估方法.首先建立了汽车内饰评估的增强现实软硬件环境,将虚拟汽车模型准确、实时地叠加到真实的驾驶环境中;其次建立了虚拟视锥体几何模型,设计了用户左右眼视锥的标定方法以及基于视线碰撞检测的A柱盲区角计算方法,并分析了标定误差对盲区角计算精度的影响,结果表明标定方法可靠.最后采用某型轿车模型进行应用验证,通过跟踪用户人眼位置驱动虚拟视锥体,实现不同驾姿下的A立柱盲区角的快速计算,主观地评估A立柱对前方视野的影响.结果表明,该方法操作简单有效,为汽车视野A立柱评估提供了一个新型工具.     

Supporting cartoon animation techniques in direct manipulation graphical user interfaces

If judiciously applied, the techniques of cartoon animation can enhance the illusion of direct manipulation that many human computer interfaces strive to present. In particular, animation can convey a feeling of substance in the objects that a user manipulates, strengthening the sense that real work is being done. This paper describes algorithms and implementation issues to support cartoon style graphical object distortion effects for direct manipulation user interfaces. Our approach is based on suggesting a range of animation effects by distorting the view of the manipulated object. To explore the idea, we added a warping transformation capability to the InterViews user interface toolkit.     

基于模糊多目标决策的两跳中继蜂窝网络切换算法

简要介绍了在集成两跳Ad Hoc和蜂窝网络的结构下,触发网络进行切换的一些因素和两种路由代理发现算法,并且提出了一种新的基于模糊多目标决策方法的切换决定算法。算法从层次分析和模糊综合评价理论的思想出发,结合用户、终端、业务和网络信息,对网络链路的性能进行综合评价,选择出最适合用户业务请求的路径。仿真显示在用户可感知业务QoS下降的情况下,算法可以通过增加QoS的权重而切换到更好的网络链路上,从而为用户提供了“总是最好连接”的服务。     

Rapid geometric modeling for visual simulation using semi-automated reconstruction from single image

This paper presents a novel algorithm that enables the semi-automatic reconstruction of human-made structures (e.g., buildings) into piecewise planar 3D models from a single image. This allows the models to be readily used in virtual or augmented reality visual simulations or for data acquisition in 3D geographic information systems. Contrary to traditional labor-intensive but accurate single view reconstruction (SVR) solutions based purely on geometric constraints, and contrary to recent fully automatic albeit low-accuracy SVR algorithms based on statistical inference, the presented method achieves a compromise between speed and accuracy, leading to less user input and acceptable visual effects. The user input required in the presented approach is primarily a line drawing that represents an outline of the building to be reconstructed. Using this input, the developed method takes advantage of a newly proposed vanishing point (VP) detection algorithm that can simultaneously estimate multiple VPs in an image. With those VPs, the normal direction of planes—which are projected onto the image plane as polygons in the line drawing—can be automatically calculated. Following this step, a linear system similar to the traditional SVR solutions can be used to achieve 3D reconstruction. Experiments that demonstrate the efficacy and visual outcome of the developed method are also described, highlighting the method’s potential use for rapid geometric model building of surrounding structures in visual simulation of engineering processes.     

Reconstructing convex sets from support line measurements

Algorithms are proposed for reconstructing convex sets given noisy support line measurements. It is observed that a set of measured support lines may not be consistent with any set in the plane. A theory of consistent support lines which serves as a basis for reconstruction algorithms that take the form of constrained optimization algorithms is developed. The formal statement of the problem and constraints reveals a rich geometry that makes it possible to include prior information about object position and boundary smoothness. The algorithms, which use explicit noise models and prior knowledge, are based on maximum-likelihood and maximum a posteriori estimation principles and are implemented using efficient linear and quadratic programming codes. Experimental results are presented. This research sets the stage for a more general approach to the incorporation of prior information concerning the estimation of object shape     

Animating with style: defining expressive semantics of motion

Actions performed by a virtual character can be controlled with verbal commands such as ‘walk five steps forward’. Similar control of the motion style, meaning how the actions are performed, is complicated by the ambiguity of describing individual motions with phrases such as ‘aggressive walking’. In this paper, we present a method for controlling motion style with relative commands such as ‘do the same, but more sadly’. Based on acted example motions, comparative annotations, and a set of calculated motion features, relative styles can be defined as vectors in the feature space. We present a new method for creating these style vectors by finding out which features are essential for a style to be perceived and eliminating those that show only incidental correlations with the style. We show with a user study that our feature selection procedure is more accurate than earlier methods for creating style vectors, and that the style definitions generalize across different actors and annotators. We also present a tool enabling interactive control of parametric motion synthesis by verbal commands. As the control method is independent from the generation of motion, it can be applied to virtually any parametric synthesis method.     

AutoStyle: Automatic Style Transfer from Image Collections to Users' Images

Stylizing photos, to give them an antique or artistic look, has become popular in recent years. The available stylization filters, however, are usually created manually by artists, resulting in a narrow set of choices. Moreover, it can be difficult for the user to select a desired filter, since the filters’ names often do not convey their functions. We investigate an approach to photo filtering in which the user provides one or more keywords, and the desired style is defined by the set of images returned by searching the web for those keywords. Our method clusters the returned images, allows the user to select a cluster, then stylizes the user's photos by transferring vignetting, color, and local contrast from that cluster. This approach vastly expands the range of available styles, and gives each filter a meaningful name by default. We demonstrate that our method is able to robustly transfer a wide range of styles from image collections to users’ photos.     

Algorithms for matching 3D line sets

Matching two sets of lines is a basic tool that has applications in many computer vision problems such as scene registration, object recognition, motion estimation, and others. Line sets may be composed of infinitely long lines or finite length line segments. Depending on line lengths, three basic cases arise in matching sets of lines: 1) finite-finite, 2) finite-infinite, and 3) infinite-infinite. Case 2 has not been treated in the literature. For Cases 1 and 3, existing algorithms for matching 3D line sets are not completely satisfactory in that they either solve special situations, or give approximate solutions, or may not converge, or are not invariant with respect to coordinate system transforms. In this paper, we present new algorithms that solve exactly all three cases for the general situation. The algorithms are provably convergent and invariant to coordinate transforms. Experiments with synthetic and real 3D image data are reported.     

A command structured approach to structural object plotting and automated line dimensioning

The command structured DRAW1 system is a comprehensive plot program which allows the user to generate, position, display and dimension a complex object. Views or frames of the object in orthographic or perspective projections are automatically generated and displayed based upon commands denned by the engineer. The dimensioning of lines or points within a viewing frame is possible by using the standard criteria provided by the program, a user modification of that standard, or an original criteria selection defined by the user.Frame generation and base manipulation are effectively managed by a command interpreter and a flexible series of command forms. The command interpreter reads and interprets all information supplied to the system from a main line program. Real, integer, text and command form data are directed to a form interpreter which verifies the proper form and related element sequence. Free format command forms are provided to facilitate the manipulation of graphic data.Command and associated data are used to define, position and list all active coordinate and line information about a given object. Orthographic or perspective projections of an object are easily generated using pitch, yaw and roll commands to incrementally rotate the object into desired positions or orientations for frame plots.The automated dimensioning of a structured object may be accomplished by using the provided program standard criteria, which allows the user to select different types of arrow heads, dimensioning lines, architectural or engineering formats, stacking heights and dimensioning units. Any part of the standard criteria may be modified to better suit the user's needs; or, he may select his own special dimensioning criteria for his particular application. The user may define a standard dimensioning form to be used in dimensioning any line or line group.     

一种视频质量监测系统的设计与实现

网络服务提供商希望能从用户的角度了解目前网络所提供的服务质量,而用户也希望获得定量的指标来评价当前网络服务质量。为此,以视频质量监测为研究对象,提出一种面向用户体验质量的网络监测系统。通过实验分析了网络传输过程中QoS参数对视频QoE的影响;提出一种将视频流转化为测试序列的视频丢包测量方法,该方法能低入侵、准确测量视频传输过程中的丢包情况;基于以上的研究成果,通过对MIB库的扩展和对MIB库轮询机制的研究,构建了面向QoE的视频服务监测系统,该监测系统结构简单、可行性强,实验表明可实时对网络中的视频服务质量进行监测。     

一种改进的用户浏览偏爱路径挖掘方法

提出一种基于“三矩阵”模型的偏爱浏览路径的挖掘方法。在单元数组存储结构（存储矩阵）基础上建立以浏览兴趣度为基本元素的会话矩阵和路径矩阵。在会话矩阵上采用2个页面向量夹角余弦作为相似用户的页面距离公式进行页面聚类,求得相似用户的相关页面集。并利用路径选择偏爱度在相似用户的路径矩阵上挖掘出相似用户的浏览偏爱路径。实验证明,该方法是合理有效的,能够得到更精准的用户偏爱浏览路径。     

User Behavior Model Based on Affordances and Emotions: A New Approach for an Optimal Use Method in Product–User Interactions

This study proposes a new approach to developing a user behavior model to explain how a user finds the optimal use. This is achieved by considering user concerns, task significances, affordances, and emotional responses as the interaction components and by exploring behavior sequences for a goal in using a product the first time. The tasks in the same group at each level in the user concern structure are therefore in a competing relationship in going up to a higher task. The task tree with the significances and the affordance probabilities can be analyzed. The order of a user’s exploring behavior sequences can be determined through comparisons of the expected significances, which can be obtained by the modified subjective expected utility theory. A user’s emotional responses for the tasks that a behavior sequence is composed of can be calculated by the modified decision affect theory. Here, the emotional response refers to a user’s internal reactions for the degree to which a product’s affordance features can meet his or her mental model in use. The average emotional response for a behavior sequence can be a user’s decisional factor for the optimal use method in using a product with a goal. Also, the design problems of a product can be checked from users’ point of view, and the emotional losses/changes by usage failures can be discussed. For an illustrative purpose, the proposed model is applied to a numerical example with some assumptions.     

具有用户特征约束的多关系聚类

多数聚类算法都是针对数据本身,往往忽略了用户聚类目的以及聚类过程中用户的参与指导,这样从数据本身出发的聚类结果准确性往往不太理想。针对这个问题,提出具有用户特征约束的多关系聚类算法。在多关系关联数据中进行用户参与的特征选择,用Must特征集和Can’t特征集描述用户聚类目的,通过领域本体进行特征集合扩充,得到聚类特征集合进行聚类。实验表明,该算法能较好地描述用户聚类目的,实现用户参与的聚类指导,获得了较好的聚类结果。     

基于三条相互垂直直线的单目位姿估计

基于单目视觉的位姿估计是计算机视觉中的典型问题之一。文中利用目标物体上的三条相互垂直的直线特征和相机像平面上这些特征的对应获得已标定相机相对于目标物体的位姿参数,给出其闭式求解方法,并证明问题解的数量与相机光心和三条直线的相对位置有关。当光心位于两个特殊平面以外时存在唯一解,反之若在该两个平面之间则存在两个解,并且这两个解具有对称性,该性质可作为合理解的判别依据。由于三条相互垂直的直线是长方体的三条边缘,而长方体在现实世界中广泛存在,该结论为应用直线特征进行单目视觉位姿估计及合作目标设计提供理论依据。     

Labeling Line Drawings with Hidden-Part-Drawn of Planar Object with Trihedral Vertices

Although line drawings consist of only line segments on a plane, they convey much information about the three-dimensional object structures. For a computer interpreting line drawings, some intelligent mechanism is required to extract three-dimensional information from the two-dimensional line drawings. In this paper, a new labeling theory and method are proposed for the two-dimensional line drawing with hidden-part-draw of a three-dimensional planar object with trihedral vertices. Some rules for labeling line drawing are established. There are 24 kinds of possible junctions for line drawing with hidden-part-draw, in which there are 8 possible Y and 16 W junctions. The three problems are solved that Sugihara's line drawing labeling technique exists. By analyzing the projections of the holes in manifold planar object, we have put forward a labeling method for the line drawing. Our labeling theory and method can discriminate between correct and incorrect hidden-part-draw natural line drawings. The hidden-part-draw natural line drawings can be labeled correctly by our labeling theory and method, whereas the labeling theory of Sugihara can only label the hidden-part-draw unnatural line drawings in which some visible lines must be drawn as hidden lines, and some invisible lines must be drawn as continuous lines.     

A Fisher-Rao Metric for Paracatadioptric Images of Lines

In a central paracatadioptric imaging system a perspective camera takes an image of a scene reflected in a paraboloidal mirror. A 360° field of view is obtained, but the image is severely distorted. In particular, straight lines in the scene project to circles in the image. These distortions make it difficult to detect projected lines using standard image processing algorithms. The distortions are removed using a Fisher-Rao metric which is defined on the space of projected lines in the paracatadioptric image. The space of projected lines is divided into subsets such that on each subset the Fisher-Rao metric is closely approximated by the Euclidean metric. Each subset is sampled at the vertices of a square grid and values are assigned to the sampled points using an adaptation of the trace transform. The result is a set of digital images to which standard image processing algorithms can be applied. The effectiveness of this approach to line detection is illustrated using two algorithms, both of which are based on the Sobel edge operator. The task of line detection is reduced to the task of finding isolated peaks in a Sobel image. An experimental comparison is made between these two algorithms and third algorithm taken from the literature and based on the Hough transform.     

基于评分填充和时间的加权Slope One算法

针对数据稀疏性,常用的评分矩阵填充方法主要是通过平均数、中位数等进行填充,该文提出一种新的评分矩阵填充方法。利用项目-属性矩阵计算用户对项目属性偏好,由于每个项目都有各自属性,从而可以获得用户对项目的偏好值,以用户平均评分为基准,实现对评分矩阵填充。基于填充后的评分矩阵,又考虑到用户兴趣爱好随时间会发生改变,因此引入时间因子,提出一种基于评分矩阵填充和时间因子的加权slope one算法(FTWSOA)。通过时间函数修正评分矩阵,优化的评分数据可以更好地体现用户兴趣爱好随时间变化的情况。在时间加权的评分矩阵下,计算出属性兴趣偏好,在共同评分很少甚至没有时,利用属性兴趣偏好可以较为准确地计算用户相似度。由于在共同很少或者没有时,原始评分矩阵中用户没有交集,而在属性兴趣矩阵下用户会存在交集,因此,使用参数λ将填充矩阵下的用户相似度和属性兴趣偏好矩阵下的用户相似度相结合得到最终的用户相似度,可以缓解在稀疏数据下相似度计算性能差的问题,最后使用加权slope one预测评分时,将时间衰减函数加入到预测公式中来优化预测评分公式。通过在MovieLens100k数据集上的实验表明,相比于其他算法,FTWSOA算法准确度有所提高。