鱼眼镜头的标定和畸变校正研究

为在使用鱼眼镜头得到大视野图像的同时得到正常的视觉效果,研究鱼眼镜头的成像模型及内外参数的标定过程.相比常用的标定算法,采用基于镜头模型的标定方法;针对Davide Scaramuzza提出的全方位相机标定工具箱,指出其不足之处,对角点坐标的精度、标定系数矩阵稳定性和角点范围随意性三方面进行优化和提高;根据标定结果对鱼眼畸变图像进行畸变校正,得到正常视觉的平面图.实验结果表明,优化后的方法实现简单、鲁棒性强、结果准确.     

煤矿鱼眼畸变图像校正

针对煤矿井下视频监控系统中鱼眼图像的畸变问题,根据理想球面透视投影模型的保线性约束条件,提出一种面向内容的校正参数自动获取方法,即通过对鱼眼畸变图像进行数学形态学和随机霍夫变换预处理得到所需的图像边缘特征直线,然后统计水平和垂直线段在总线段中的比例,分析统计结果,获取最佳校正参数。为了减少图像信息过多对校正参数获取过程的影响,对理想球面透视投影模型进行了改进,提出一种改进的鱼眼畸变图像校正方法,实现了对图像中心的转移和部分区域的放大。实验验证了该方法对鱼眼畸变图像的校正效果较好。     

User interaction with everyday lighting systems

New lighting technologies create new opportunities that may contribute to people’s experience of light. These opportunities are a result of the increased variety and freedom in terms of colour, form factor and connectivity of the lights. To allow people to fully benefit from the potential of such novel lighting systems, there is a need for a new user interaction paradigm. To develop this paradigm, we have to better understand the aspects that play a part in the interaction with lighting, paying special attention to people’s motivation for interaction. This paper reports on a context-mapping study that was performed to gain insight in these aspects. As result, we present a set of seven themes that regard the interaction with lighting in the current situation and in the future. These themes provide an overview of the relevant aspects in this domain and contain considerations and opportunities for the design of new interfaces for novel lighting systems. We conclude that people have different levels of lighting needs that are highly dependent on context and that also require control at different levels. The context and lighting needs have a large influence on the extent to which people are motivated to adjust their lighting. Moreover, the lighting interface itself has a large effect on this motivation, mainly influenced by the degrees of freedom, the control location and availability, the degree of automation and general interaction qualities.     

Camera calibration with distortion models and accuracy evaluation

A camera model that accounts for major sources of camera distortion, namely, radial, decentering, and thin prism distortions is presented. The proposed calibration procedure consists of two steps: (1) the calibration parameters are estimated using a closed-form solution based on a distribution-free camera model; and (2) the parameters estimated in the first step are improved iteratively through a nonlinear optimization, taking into account camera distortions. According to minimum variance estimation, the objective function to be minimized is the mean-square discrepancy between the observed image points and their inferred image projections computed with the estimated calibration parameters. The authors introduce a type of measure that can be used to directly evaluate the performance of calibration and compare calibrations among different systems. The validity and performance of the calibration procedure are tested with both synthetic data and real images taken by tele- and wide-angle lenses     

User interface based on natural interaction design for seniors

With world population ageing, how to help seniors to adapt to technology life is an important issue. Technology is becoming life rather than resistance, because many of the technology applications are often accompanied by a lot of information to process. This makes the user interface to become an important bridge between human computer interactions. Especially the inconvenience caused by human ageing, these related issues from the cognitive and operational of products are derived. This study proposes a study of user interface design based on natural interaction to increase seniors’ usage intention. In the proposed contents, the Kinect sensor is used to retrieve seniors’ in-depth information in movements, thus the user interface of system can be operated by the gesture intuitively. In the framework of the system, in the first all, the morphology is applied to identify the features of a hand from depth values obtained from the sensor. Gesture is used to recognize operating behavior of users to implement the interactive action, and collision detection is applied to confirm effectiveness of operation. On the other hand, through interpretive structural model (ISM), each design element of interactive interface can be decomposed and realized, and the solution for target and direction of design problem is also proposed. At the meanwhile, the concept of affordance is conducted to the development of interface for graphic users that proposed in this study, and the design achievement contains operation and usability of intuition can further be acquired. Finally, based on the proposed methodology, an intuitive user interface of digital devices is constructed by Java programming language that allows for verifying the feasibility of user interface for seniors. Besides, the proposed method can be widely used to develop the user interface for various products.     

Density in scatterplots and the estimation of correlation

The construction of a graphical presentation involves the representation of information by means of visual symbols. The acquisition of information from the resultant graph is a perceptual process that involves the decoding and interpretation of the visual symbols. Hence good design decisions will be based on an understanding of the information acquisition process and in particular graphical perception. This study examines the perception of bivariate normal data presented in a scatter diagram, and creates a model that successfully explains how individuals perceive the information contained in scatterplots

Subjects were shown a series of scatter diagrams on the CRT of a microcomputer and were asked to estimate correlation. Several variables were examined that explain estimated correlation including regression slope, dispersion, number of points displayed, and the size of the CRT screen. All of these factors were found to significantly affect subjects' estimates of correlation.     

User interaction in digital libraries: coping with diversity through adaptation

User interface adaptations can be used to address several user interaction challenges in the development of digital library systems. This paper: (a) examines some of the intrinsic characteristics of digital library systems; (b) identifies some of the key Human–Computer Interaction (HCI) challenges in relation to design and architectural abstraction for user interfaces to digital library systems; and (c) develops an argumentation for adaptations in digital library systems. By drawing parallels to recent HCI research into adaptable and adaptive user interaction, the paper illustrates potential areas in which user interface adaptation can provide a useful technique for advancing the quality of human interaction with a digital library system. Received: 18 December 1998 / Revised: 31 May 1999     

User acceptance and corporate intranet quality: An evaluation with iQual

We developed a model for intranet quality and acceptance; it was applied to data collected by the sales and marketing division of an international manufacturing company obtained via a Web survey (n = 131) and tested using partial least squares path modeling. A strong explanation of behavioral intentions was revealed. The results showed that intranet quality (composed of usability, design, and information quality) was a significant factor in determining behavioral intention to use, although it was less important than perceived usefulness and social influence. Comments collected from respondents were analyzed via content analysis and further used to illustrate the findings.     

Improving Web interaction on small displays

Soon many people will retrieve information from the Web using handheld, palmsized or even smaller computers. Although these computers have dramatically increased in sophistication, their display size is — and will remain — much smaller than their conventional, desktop counterparts. Currently, browsers for these devices present Web pages without taking account of the very different display capabilities. As part of a collaborative project with Reuters, we carried out a study into the usability impact of small displays for retrieval tasks. Users of the small screen were 50% less effective in completing tasks than the large screen subjects. Small screen users used a very substantial number of scroll activities in attempting to complete the tasks. Our study also provided us with interesting insights into the shifts in approach users seem to make when using a small screen device for retrieval. These results suggest that the metaphors useful in a full screen desktop environment are not the most appropriate for the new devices. Design guidelines are discussed, here, proposing directed access methods for effective small screen interaction. In our ongoing work, we are developing such `meta-interfaces' which will sit between the small screen user and the `conventional' Web page.     

Peer interaction and learning with computers in small groups

While anecdotal reports of computer use in classrooms suggest that students often work together, few studies have focused on the interaction between students or on its consequences for achievement. This paper reviews the research on peer interaction with computers to determine its effects on learning. The purposes of this review are to determine (a) the advantages or disadvantages of group work for learning, (b) the kinds of verbal interaction that occur when students work together at the computer, and (c) the kinds of interaction that are beneficial or detrimental for learning. This paper considers the possible cognitive and socioemotional processes that mediate the effects of peer interaction on learning, and discusses the implications of the research findings for the design of computer software.     

User oriented techniques to support interaction and decision making with large educational databases

Information Technology is developing rapidly and providing policy/decision makers with large amounts of information that require processing and analysis. Decision support systems (DSS) aim to provide tools that not only help such analyses, but enable the decision maker to experiment and simulate the effects of different policies and selection strategies. The specific context of this research, set in Saudi Arabia, is administrative decision making using large educational databases.     

An evaluation of semantic fisheye views for opportunistic search in an annotated image collection

Visual interfaces are potentially powerful tools for users to explore a representation of a collection and opportunistically discover information that will guide them toward relevant documents. Semantic fisheye views (SFEVs) are focus + context visualization techniques that manage visual complexity by selectively emphasizing and increasing the detail of information related to the users focus and deemphasizing or filtering less important information.In this paper we describe a prototype for visualizing an annotated image collection and an experiment to compare the effectiveness of two distinctly different SFEVs for a complex opportunistic search task. The first SFEV calculates relevance based on keyword-content similarity and the second based on conceptual relationships between images derived using WordNet. The results of the experiment suggest that semantic-guided search is significantly more effective than similarity-guided search for discovering and using domain knowledge in a collection.     

Usability evaluation of navigation tasks by people with intellectual disabilities: a Google and SAPO comparative study regarding different interaction modalities

Universal Access in the Information Society - This paper presents a case study regarding the usability evaluation of navigation tasks by people with intellectual disabilities. The aim was to...     

User evaluation of a market-based recommender system

Recommender systems have been developed for a wide variety of applications (ranging from books, to holidays, to web pages). These systems have used a number of different approaches, since no one technique is best for all users in all situations. Given this, we believe that to be effective, systems should incorporate a wide variety of such techniques and then some form of overarching framework should be put in place to coordinate them so that only the best recommendations (from whatever source) are presented to the user. To this end, in our previous work, we detailed a market-based approach in which various recommender agents competed with one another to present their recommendations to the user. We showed through theoretical analysis and empirical evaluation with simulated users that an appropriately designed marketplace should be able to provide effective coordination. Building on this, we now report on the development of this multi-agent system and its evaluation with real users. Specifically, we show that our system is capable of consistently giving high quality recommendations, that the best recommendations that could be put forward are actually put forward, and that the combination of recommenders performs better than any constituent recommender.     

A new data hiding scheme for binary image authentication with small image distortion

A new data hiding scheme for binary image authentication that has a small distortion of the cover image is proposed in this paper. Using the data-embedding algorithm that is based on Hamming codes, the proposed scheme embeds authentication information into the cover image with flipping only a small number of pixels. A special type of the pixels are selected and flipped by a new algorithm to minimize visual distortion. This new algorithm is based on ELSSM (Edge Line Segment Similarity Measure). Randomly shuffling the bit-order of the authentication information to be embedded, the information can only be extracted by the designated receiver who has the symmetric key. We employ two measurement metrics: miss detection rates for the degree of security and PSNR (Peak Signal-to-Noise Ratio) and ELSSM for the degree of the image distortion to demonstrate the feasibility of the proposed scheme. Using these metrics, we analyze the proposed scheme and the previous schemes. The analysis reveals that the proposed scheme requires less image distortion than the previous schemes whilst achieving the same level of the miss detection rate. Experimental results demonstrate that the proposed scheme is more resilient against recent steganalysis attacks than the previous schemes.     

User representations of computer systems in human-computer speech interaction

We report an experiment designed to study whether models of human-human voice dialogues can be applied successfully to human-computer communication using natural spoken language. Two groups of six subjects were asked to obtain information about air travel via dialogue with a remote "travel agent". Subjects in the computer group were led to believe they were talking to a computer whereas subjects in the operator group were told they were talking to a human. Both groups of subjects actually talked to the same human experimenter. The study focuses on subjects' representations of interlocutor skill and knowledge, and differs from previous analogous studies in several respects: the task is more complex, giving rise to structured exchanges in natural language rather than to question/answer pairs in simplified language; specific attention has been paid to the design, which attempts to avoid biases that have flawed other studies (in particular, conditions are identical for both groups); the time factor has been taken into account (subjects take part in three sessions, at 1-week intervals).Some results confirm those of the literature, namely that subjects of the computer group tend to control and simplify their use of language more than those in the operator group. However, most observations are either new or in contradiction with previous results: subjects in the computer group produce more utterances but no significant differences were observed with respect to most structural and pragmatic features of language; the time factor plays a dual role. Subjects in both groups tend to become more concise. Operator group strategies differ significantly across sessions as regards scenario processing (problem solving) whereas computer group strategies remain stable.These differences in behavior between groups are ascribed to differences in representations of interlocutor ability.     

基于曲线曲面演化的图像放大方法

用Snake内部能量作为图像水平线的先验模型,其梯度下降流是一个关于图像水平线的演化方程。由这个演化方程,利用曲面演化和其水平线演化之间的关系,得到关于图像曲面的演化方程。用这个曲线曲面演化方程进行图像放大,其几何意义是在空间Wv,s中选择使图像的Snake内部能量最小的放大方法。实验表明,该方法在相当的时间内可以得到更清晰的放大结果。     

体感交互虚拟漫游的沉浸感评价

沉浸感是虚拟漫游的重要特征,目前体感交互的虚拟漫游存在严重的感知失真问 题,虚拟场景运动的视觉感知与人机交互的体感感知不能相互匹配,破坏了虚拟漫游的沉浸感。 基于Catmull-Rom 曲线的非等距插值算法、等距插值算法和实时插值算法,分别构建3 种不同 的虚拟漫游路径,评价体感交互虚拟漫游的沉浸感。主观评价实验和仿真实验的结果表明： Catmull-Rom 曲线的非等距插值漫游路径,无论是匀速漫游还是变速漫游,均存在明显的感知 失真现象;基于Catmull-Rom 曲线的等距插值漫游路径适用于匀速漫游,但不太适合用于变速 漫游;基于Catmull-Rom 曲线的实时插值漫游路径能实现真实运动速度与场景运动速度的匹配, 较好地解决虚拟漫游时视觉感知与身体运动感知不一致的问题,增强了虚拟漫游的沉浸感。     

User Personality and User Satisfaction with Recommender Systems

In this study, we show that individual users’ preferences for the level of diversity, popularity, and serendipity in recommendation lists cannot be inferred from their ratings alone. We demonstrate that we can extract strong signals about individual preferences for recommendation diversity, popularity and serendipity by measuring their personality traits. We conducted an online experiment with over 1,800 users for six months on a live recommendation system. In this experiment, we asked users to evaluate a list of movie recommendations with different levels of diversity, popularity, and serendipity. Then, we assessed users’ personality traits using the Ten-item Personality Inventory (TIPI). We found that ratings-based recommender systems may often fail to deliver preferred levels of diversity, popularity, and serendipity for their users (e.g. users with high-serendipity preferences). We also found that users with different personalities have different preferences for these three recommendation properties. Our work suggests that we can improve user satisfaction when we integrate users’ personality traits into the process of generating recommendations.     

Non-visual interaction with graphs assisted with directional-predictive sounds and vibrations: a comparative study

Blind and visually impaired students need special educational and developmental tools to allow them to interact with graphic entities on PDA and desktop platforms. In previous research, stylus movements regarding the hidden graph were sonified with three directional-predictive sound (DPS) signals, taking into account an exploration behavior and the concept of the capture radius. The results indicated that the scanpaths were by 24–40% shorter in length and task completion times decreased by 20–25%. The goal of the study presented in this paper was to measure and compare the subjective performance recorded with directional-predictive vibrations (DPV) regarding the subjective performance achieved when the hidden graphic images were explored with DPS. The study also aimed to find out which kind of feedback cues would require less cognitive efforts in interpreting their meaning. The prototype of vibro-tactile pen with embedded vibration motor was used to produce DPV instead of sounds. The performance of eight blindfolded subjects was investigated in terms of the number of both feedbacks used and the time spent to complete non-visual inspection of the hidden graphs. There was a statistically significant difference between the average number of DPS and vibrations and task completion time taken by the players to discover the features of hidden graphs being explored with different capture radius. The experimental findings confirmed the beneficial use of DPS signals in the task when cross-modal coordination should benefit the user in the absence of visual information when compared with DPV patterns.