3-D interpretation of optical flow by renormalization

This article studies 3-D interpretation of optical flow induced by a general camera motion relative to a surface of general shape. First, we describe, using the image sphere representation, an analytical procedure that yields an exact solution when the data are exact: we solve theepipolar equation written in terms of theessential parameters and thetwisted optical flow. Introducing a simple model of noise, we then show that the solution is statistically biased. In order to remove the statistical bias, we propose an algorithm calledrenormalization, which automatically adjusts to unknown image noise. A brief discussion is also given to thecritical surface that yields ambiguous 3-D interpretations and the use of theimage plane representation.     

Employing both gender and emotion cues to enhance speaker identification performance in emotional talking environments

Speaker recognition performance in emotional talking environments is not as high as it is in neutral talking environments. This work focuses on proposing, implementing, and evaluating a new approach to enhance the performance in emotional talking environments. The new proposed approach is based on identifying the unknown speaker using both his/her gender and emotion cues. Both Hidden Markov Models (HMMs) and Suprasegmental Hidden Markov Models (SPHMMs) have been used as classifiers in this work. This approach has been tested on our collected emotional speech database which is composed of six emotions. The results of this work show that speaker identification performance based on using both gender and emotion cues is higher than that based on using gender cues only, emotion cues only, and neither gender nor emotion cues by 7.22 %, 4.45 %, and 19.56 %, respectively. This work also shows that the optimum speaker identification performance takes place when the classifiers are completely biased towards suprasegmental models and no impact of acoustic models in the emotional talking environments. The achieved average speaker identification performance based on the new proposed approach falls within 2.35 % of that obtained in subjective evaluation by human judges.     

Communication in virtual environments: The influence of spatial cues and gender on verbal behavior

As communication technologies continue to evolve, more people will engage in virtual social interactions. With this trend comes an increasing need for research on behavior within virtual worlds. This study contributes to that agenda by focusing on the influence of physical attributes of a virtual setting and gender on verbal behavior expressed by mixed-gender dyads in a virtual world. Computerized text analyses revealed linguistic differences as a function of both the physical and social complexity of virtual settings and gender. The latter differences included both quantitative and qualitative features of written communication. These results add important new discoveries to the literature on virtual psychology and highlight the value of using text analysis tools to investigate virtual interactions.     

Character navigation in dynamic environments based on optical flow

Steering and navigation are important components of character animation systems to enable them to autonomously move in their environment. In this work, we propose a synthetic vision model that uses visual features to steer agents through dynamic environments. Our agents perceive optical flow resulting from their relative motion with the objects of the environment. The optical flow is then segmented and processed to extract visual features such as the focus of expansion and time‐to‐collision. Then, we establish the relations between these visual features and the agent motion, and use them to design a set of control functions which allow characters to perform object‐dependent tasks, such as following, avoiding and reaching. Control functions are then combined to let characters perform more complex navigation tasks in dynamic environments, such as reaching a goal while avoiding multiple obstacles. Agent's motion is achieved by local minimization of these functions. We demonstrate the efficiency of our approach through a number of scenarios. Our work sets the basis for building a character animation system which imitates human sensorimotor actions. It opens new perspectives to achieve realistic simulation of human characters taking into account perceptual factors, such as the lighting conditions of the environment.     

Intelligibility of speech in a virtual 3-D environment

In a simulated air traffic control task, improvement in the detection of auditory warnings when using virtual 3-D audio depended on the spatial configuration of the sounds. Performance improved substantially when two of four sources were placed to the left and the remaining two were placed to the right of the participant. Surprisingly, little or no benefits were observed for configurations involving the elevation or transverse (front/back) dimensions of virtual space, suggesting that position on the interaural (left/right) axis is the crucial factor to consider in auditory display design. The relative importance of interaural spacing effects was corroborated in a second, free-field (real space) experiment. Two additional experiments showed that (a) positioning signals to the side of the listener is superior to placing them in front even when two sounds are presented in the same location, and (b) the optimal distance on the interaural axis varies with the amplitude of the sounds. These results are well predicted by the behavior of an ideal observer under the different display conditions. This suggests that guidelines for auditory display design that allow for effective perception of speech information can be developed from an analysis of the physical sound patterns.     

3-D motion estimation by integrating visual cues in 2-D multi-modal opti-acoustic stereo sequences

Object reconstruction and target-based positioning are among critical capabilities in deploying submersible platforms for a range of underwater applications, e.g., search and inspection missions. Optical cameras provide high-resolution and target details, but their utility becomes constrained by the visibility range. In comparison, high-frequency (MHz) 2-D sonar imaging systems introduced to the commercial market in recent years can image targets at distances of tens of meters in highly turbid waters.Where fair visibility permits optical imaging at reasonable quality, the integration with 2-D sonar data can enable better performance compared to deploying either system alone, and thus enabling automated operation in a wider range of conditions.We investigate the estimation of 3-D motion by exploiting the visual cues in optical and sonar video for vision-based navigation and 3-D positioning of submersible platforms. The application of structure from motion paradigm in this multi-modal imaging scenario also enables the 3-D reconstruction of scene features. Our method does not require establishing multi-modal association between corresponding optical and sonar features, but rather the tracking of features in the sonar and optical motion sequences independently. In addition to improving the motion estimation accuracy, another advantage of the proposed method includes overcoming the inherent ambiguities of monocular vision, e.g., the scale-factor ambiguity and dual interpretation of motion relative to planar scenes. We discuss how our solution can also provide an effective strategy to address the complex opti-acoustic stereo matching problem. Experiment with synthetic and real data demonstrate the advantages of our technical contribution.     

Comparing effects of 2-D and 3-D visual cues during aurally aided target acquisition

The aim of the present study was to investigate interactions between vision and audition during a visual target acquisition task performed in a virtual environment. In two experiments, participants were required to perform an acquisition task guided by auditory and/or visual cues. In both experiments the auditory cues were constructed using virtual 3-D sound techniques based on nonindividualized head-related transfer functions. In Experiment 1 the visual cue was constructed in the form of a continuously updated 2-D arrow. In Experiment 2 the visual cue was a nonstereoscopic, perspective-based 3-D arrow. The results suggested that virtual spatial auditory cues reduced acquisition time but were not as effective as the virtual visual cues. Experiencing the 3-D perspective-based arrow rather than the 2-D arrow produced a faster acquisition time not only in the visually aided conditions but also when the auditory cues were presented in isolation. Suggested novel applications include providing 3-D nonstereoscopic, perspective-based visual information on radar displays, which may lead to a better integration with spatial virtual auditory information.     

3-D route-planning support for navigation in a complex indoor environment

Three-dimensional (3-D) route-planning support offers a promising solution to overcome problems with wayfinding in complex indoor environments. An experiment was conducted to test the effect of 3-D route-planning support in a realistic setting, a large hospital building, during normal operation. Forty participants performed navigation tasks either with (n?=?20) or without (n?=?20) 3-D route-planning support. Support resulted in faster navigation, more use of artwork specifically installed to aid wayfinding, fewer navigation errors, less disorientation and less anxiety. In addition, participants used different strategies for wayfinding: without navigation support they used signs and route colour, but with navigation support they used not only the artwork, but also the existing furniture and other landmarks. The acceptance of 3-D route-planning support was high. Overall, the results support the value of 3-D route-planning support.     

Spatial orientation in 3-D desktop displays: using rooms for organizing information

Understanding how spatial knowledge is acquired is important for spatial navigation and for improving the design of 3-D perspective interfaces. Configural spatial knowledge of object locations inside rooms is learned rapidly and easily (Colle & Reid, 1998), possibly because rooms afford local viewing in which objects are directly viewed or, alternatively, because of their structural features. The local viewing hypothesis predicts that the layout of objects outside of rooms also should be rapidly acquired when walls are removed and rooms are sufficiently close that participants can directly view and identify objects. It was evaluated using pointing and sketch map measures of configural knowledge with and without walls by varying distance, lighting levels, and observation instructions. Although within-room spatial knowledge was uniformly good, local viewing was not sufficient for improving spatial knowledge of objects in different rooms. Implications for navigation and 3-D interface design are discussed. Actual or potential applications of this research include the design of user interfaces, especially interfaces with 3-D displays.     

Autonomous navigation and environment modeling for MAVs in 3-D enclosed industrial environments

In many applications, the industrial environments are typically 3-D indoor spaces enclosed by shell style structures, which are highly complex with known or unknown non-convex obstacles. GPS signal is unreliable or even unavailable inside, which poses significant technical challenges for the state estimation of micro aerial vehicles (MAVs) performing exploration and modeling tasks in such environments. In this paper, requirements and challenges for 3-D enclosed industrial environments exploration are analyzed firstly, and then state-of-art developments of MAV systems, environment modeling, visual navigation and guidance technologies are reviewed. A robust RGB-D odometry is introduced into the system to provide airborne 6-DOF state estimates of the MAV, which are fused with inertial measurements. Then the fused state information is used to assist the RGB-D based real time 3-D environment modeling. An improved closed-loop RRT based path planning approach (BI-RRT) is developed for information-efficient environment explorations. A flight experimental platform is constructed and the proposed system is validated in flight experiments.     

The persistence of the gender gap in computing

16–18 year old polytechnic entrants, who had enrolled for business or natural science subjects in 1986 or 1989, were studied to assess the persistence of the gender gap in computing. Whilst 1989 entrants were more knowledgeable about computing, the gender gap in favour of males persisted. Reported use of computers, particularly a students own computer, was higher in 1989, but again the gender gap persisted. The 1989 entrants were asked why they had chosen not to study computer studies, using open ended and fixed answer questions. Whilst gender differences did occur, gender similarity was more apparent. A negative image of the computer specialist interacting with a terminal all day was very important. It is suggested that the provision of more courses with a mixed curriculum would partially resolve the gender question.     

Robot navigation in cluttered 3-D environments using preference-based fuzzy behaviors.

Autonomous navigation systems for mobile robots have been successfully deployed for a wide range of planar ground-based tasks. However, very few counterparts of previous planar navigation systems were developed for 3-D motion, which is needed for both unmanned aerial and underwater vehicles. A novel fuzzy behavioral scheme for navigating an unmanned helicopter in cluttered 3-D spaces is developed. The 3-D navigation problem is decomposed into several identical 2-D navigation subproblems, each of which is solved by using preference-based fuzzy behaviors. Due to the shortcomings of vector summation during the fusion of the 2-D subproblems, instead of directly outputting steering subdirections by their own defuzzification processes, the intermediate preferences of the subproblems are fused to create a 3-D solution region, representing degrees of preference for the robot movement. A new defuzzification algorithm that steers the robot by finding the centroid of a 3-D convex region of maximum volume in the 3-D solution region is developed. A fuzzy speed-control system is also developed to ensure efficient and safe navigation. Substantial simulations have been carried out to demonstrate that the proposed algorithm can smoothly and effectively guide an unmanned helicopter through unknown and cluttered urban and forest environments.     

Appearance-based virtual view generation from multicamera videos captured in the 3-D room

We present an appearance-based virtual view generation method that allows viewers to fly through a real dynamic scene. The scene is captured by multiple synchronized cameras. Arbitrary views are generated by interpolating two original camera-views near the given viewpoint. The quality of the generated synthetic view is determined by the precision, consistency and density of correspondences between the two images. All or most of previous work that uses interpolation extracts the correspondences from these two images. However, not only is it difficult to do so reliably (the task requires a good stereo algorithm), but also the two images alone sometimes do not have enough information, due to problems such as occlusion. Instead, we take advantage of the fact that we have many views, from which we can extract much more reliable and comprehensive 3D geometry of the scene as a 3D model. Dense and precise correspondences between the two images, to be used for interpolation, are obtained using this constructed 3D model.     

Towards closing the gender gap in Iraq: understanding gender differences in smartphone adoption and use

ABSTRACT

This paper examines gender differences in Iraq in terms of smartphone adoption and use, with a specific focus on the factors that can affect women’s adoption and use of smartphones. The research used the mobile phone acceptance and use model. In total, 533 questionnaires were distributed to consumers aged 18-29 and the data were analyzed using partial least squares structural equation modelling. The findings revealed that the model fitted well with men and women, but the order of significance of the factors differed between the two genders. Three factors in the model had significantly different effects on behavioral intention when compared by gender. These three factors are culture-specific beliefs and values, habit and perceived relative advantage. The findings indicate that when targeting Iraqi women, other factors in addition to price must be considered.     

Navigation in 3D virtual environments: Effects of user experience and location-pointing navigation aids

In this paper, we describe the results of an experimental study whose objective was twofold: (1) comparing three navigation aids that help users perform wayfinding tasks in desktop virtual environments (VEs) by pointing out the location of objects or places; (2) evaluating the effects of user experience with 3D desktop VEs on their effectiveness with the considered navigation aids. In particular, we compared navigation performance (in terms of total time to complete an informed search task) of 48 users divided into two groups: subjects in one group had experience in navigating 3D VEs while subjects in the other group did not. The experiment comprised four conditions that differed for the navigation aid that was employed. The first and the second condition, respectively, exploited 3D and 2D arrows to point towards objects that users had to reach; in the third condition, a radar metaphor was employed to show the location of objects in the VE; the fourth condition was a control condition with no location-pointing navigation aid available. The search task was performed both in a VE representing an outdoor geographic area and in an abstract VE that did not resemble any familiar environment. For each VE, users were also asked to order the four conditions according to their preference. Results show that the navigation aid based on 3D arrows outperformed (both in terms of user performance and user preference) the others, except in the case when it was used by experienced users in the geographic VE. In that case, it was as effective as the others. Finally, in the geographic VE, experienced users took significantly less time than inexperienced users to perform the informed search, while in the abstract VE the difference was significant only in the control and the radar conditions. From a more general perspective, our study highlights the need to take into specific consideration user experience in navigating VEs when designing navigation aids and evaluating their effectiveness.     

Distance estimation with mixed real and virtual targets in stereoscopic displays

In this paper we investigated the accuracy of center-to-center distance perception in near field augmented reality visual targets viewed by stereoscopic glasses. One real and one virtual targets were presented in four layout or target orientations (two horizontal and two vertical, by altering the relative positions of real and virtual targets) at three different parallax conditions (on screen, 5 cm from screen and 10 cm from screen) and four levels of scaled between targets’ distance (10–20 cm, 20–30 cm, 30–40 cm and 40–50 cm). The result revealed overall underestimation with an accuracy of about 84%. Interestingly, it was noticed that the main effects of layout, parallax and center-to-center distance were significant. Generally, accuracy improves when targets put vertical, close to observers’ position and smaller separation of targets. Significant interactions among the three main factors were also reported. The results are of great importance as it provides guide for the developers to decide where to present targets depending on the need for relative accuracy of judgment. Some engineering implications of the result are also discussed in this paper.     

Factors influencing the design of perspective flight path displays for guidance and navigation

Many types of modern commercial aircraft are equipped with an Electronic Flight Instrument System, comprising several programmable displays. The flexibility in information presentation of these systems offers the possibility to improve the pilot-aircraft interface significantly. Future concepts, such as enhanced and synthetic vision, will further increase these possibilities. To benefit from this, research into new display concepts is being performed to allow the pilot to operate in a four-dimensional (4D) air-traffic environment, to provide improved spatial and navigational awareness, and to enable a better transition from supervisory to manual control. A possible display format is the so-called perspective flight path display, which originated approximately 40 years ago. The design of perspective flight path displays for guidance and short-term navigation requires the specification of several parameters. Suitable values for these parameters depend on requirements with respect to range and resolution of the required information, the properties of the positioning and attitude determination system, and the abilities of the human operator with respect to perception, interpretation and evaluation of information. In this paper, a review of the various factors to be considered in the design of perspective flight path displays is presented. The relations between the guidance/short-term navigation task-related requirements and the design parameters of a perspective flight path display are discussed, and the consequences of the differences between today's guidance displays and perspective flight path displays for algorithms controlling the display symbology are explained.     

塑化过程螺槽中三维流场的数值模拟

采用CROSS模型表示聚氯乙烯(PVC)的黏度特征,使用POLYFLOW软件数值模拟了塑料注射成型机螺杆计量段螺槽中熔体在塑化过程的三维等温流场,求解和分析了3条参考直线、yz截面和xy截面上不同时刻螺槽中的压强场、速度场、剪切速率场和黏度场,数值计算的结果表明:在螺棱附近区域物料的剪切速率大,物料剪切稀化作用增强,物料黏度减小。并采用粒子运动轨迹示踪的方法研究了塑化过程中注塑机粒子运动轨迹。得知塑化过程中注塑机粒子运动轨迹比挤出机复杂得多,有三种典型的运动方式:一部分粒子边旋转边向负Z方向运动、另一部分粒子在旋转的同时先向负Z方向运动后向正Z方向运动,还有一部分粒子和边旋转边向正Z方向运动。     

内循环厌氧反应器的气-液-固三相流数值模拟研究

利用计算流体动力学(CFD)方法对内循环厌氧反应器气-液-固三相流进行了三维非稳态数值模拟研究,探索了迭代时间对内循环形成过程的影响,并重点考察了反应器内Z方向上流体力学特性及三相分离器对颗粒的截留作用。结果表明,反应器内液相及固相内循环均成功形成,CFD技术能够很好地应用于IC反应器的研究;且Z方向上,一级反应室及二级反应室内固相及气相体积分率随轴向高度增大变化不大,而在径向上存在较大波动;一级提气管内液相、固相及气相轴向速度均比二级提气管内大,气含率及固含率也较大,一级厌氧反应室起到主要的水处理作用;三相分离器及气液分离器的设计对于反应器效率影响较大。     

The role of Depth and Gestalt cues in information-rich virtual environments

Managing the layout of multi-dimensional visualizations is a crucial concern for the development of effective visual analytic interfaces. In these environments, heterogeneous and multi-dimensional information must be structured and combined into data representations that demand low cognitive resources but yield accurate mental models and insights. In this paper, we use Information-Rich Virtual Environments (IRVE) to articulate crucial tradeoffs in the use of Depth and Gestalt cues in text label layouts. We present a design space and evaluation methodology to explore the usability effects of these tradeoffs and collect results from a series of user studies. These lessons are posed as a set of design guidelines to aid developers of new, advantageous interfaces and specifications.