2D human-computer interaction techniques in immersive virtual environments

Menus and dialog boxes are useful enhancements for the direct manipulation based interaction style of Virtual Environments. In this paper an implementation of 2D HCI techniques in immersive Virtual Environments is discussed. The applicability of 2D techniques for interaction with the environment is illustrated in the case of a BOOM for immersive viewing. A Pinch Glove is used as the input device to interact with the menus and dialog boxes. A programming approach to make Motif based interfacing widgets suitable for stereoscopic display is discussed. Some examples demonstrate the use of 2D HCI techniques in immersive Virtual Environments.     

An Implementation of the Viewing Pipeline in GKS-3D

Following the analysis and evaluation to the viewing pipeline of GKS-3D,a draft proposalof the international standard ofthree-dimensional computer graphics,an implementation of theviewing pipeline is further proposed in the paper and its algorithms are given in detail.Theimplementation is characterized by allowing a possible combination of the view clip andworkstation dip.     

Finally Everyone Can Work With Highly Complex 3D Models

In the past, access to 3D databases was restricted to few specialists having the appropriate CAD skills, software, and graphics hardware. The availability of inexpensive graphics support on personal computers, the Internet’s impact on private and commercial communication, and the emergence of multimedia standards provide the basis for linking CAD databases with other personal productivity and communication tools and for making them accessible to everyone at home, in schools, in hospitals, or in the industry. For example, employees that have no design expertise, customers, and suppliers would benefit from having an easy access to the 3D databases of a company for: collaborative design review, 3D-based multi-media problem reports, collaborative problem solving and tracking, online training and documentation, internet-based part purchasing and subcontracting, demonstration to customers, or advertising. This presentation will address three of the key issues that have so far limited the non-specialist’s access to 3D databases. First-time or occasional non-expert users need to become instant experts in 3D navigation through Virtual Environments or in the interactive manipulation of digital 3D models, so that they may immediately focus on their tasks, and not waste precious time learning and fighting an unnatural user interface. Immersive VR is not the panacea – other more effective techniques show promise. The data complexity found in commercial CAD databases, especially in the automotive, aerospace, and construction industries, significantly exceeds the capabilities of any interactive graphics system. This situation is not likely to change, since the growth of the complexity and availability of 3D models outpaces the performance improvement of personal computers. Research on the automatic simplification of 3D models and on the use of levels of detail to accelerate the rendering of distant portions of the scene is growing rapidly. The still limited bandwidth of internet communication channels prohibits a pervasive access to large amounts of 3D data. Recent 3D compression techniques reduce the storage requirements for polyhedral 3D models by two orders of magnitudes.     

Finally Everyone Can Work With Highly Complex 3D Models

In the past, access to 3D databases was restricted to few specialists having the appropriate CAD skills, software, and graphics hardware. The availability of inexpensive graphics support on personal computers, the Internet’s impact on private and commercial communication, and the emergence of multimedia standards provide the basis for linking CAD databases with other personal productivity and communication tools and for making them accessible to everyone at home, in schools, in hospitals, or in the industry. For example, employees that have no design expertise, customers, and suppliers would benefit from having an easy access to the 3D databases of a company for: collaborative design review, 3D-based multi-media problem reports, collaborative problem solving and tracking, online training and documentation, internet-based part purchasing and subcontracting, demonstration to customers, or advertising. This presentation will address three of the key issues that have so far limited the non-specialist’s access to 3D databases. First-time or occasional non-expert users need to become instant experts in 3D navigation through Virtual Environments or in the interactive manipulation of digital 3D models, so that they may immediately focus on their tasks, and not waste precious time learning and fighting an unnatural user interface. Immersive VR is not the panacea – other more effective techniques show promise. The data complexity found in commercial CAD databases, especially in the automotive, aerospace, and construction industries, significantly exceeds the capabilities of any interactive graphics system. This situation is not likely to change, since the growth of the complexity and availability of 3D models outpaces the performance improvement of personal computers. Research on the automatic simplification of 3D models and on the use of levels of detail to accelerate the rendering of distant portions of the scene is growing rapidly. The still limited bandwidth of internet communication channels prohibits a pervasive access to large amounts of 3D data. Recent 3D compression techniques reduce the storage requirements for polyhedral 3D models by two orders of magnitudes.     

虚拟环境中的三维立体图生成算法

虚拟环境技术是一种高度逼真的模拟人在自然环境中视、听和动等行为的人机界面技术。其中三维立体图生成是一项核心技术。本文对三维立体图显示的原理进行介绍，提出一种立体图生成算法并给出立体图实例。最后对立体图的加速问题进行了讨论。     

An Investigation of Visual Cues used to Create and Support Frames of Reference and Visual Search Tasks in Desktop Virtual Environments

Visual depth cues are combined to produce the essential depth and dimensionality of Desktop Virtual Environments (DVEs). This study discusses DVEs in terms of the visual depth cues that create and support perception of frames of references and accomplishment of visual search tasks. This paper presents the results of an investigation that identifies the effects of the experimental stimuli positions and visual depth cues: luminance, texture, relative height and motion parallax on precise depth judgements made within a DVE. Results indicate that the experimental stimuli positions significantly affect precise depth judgements, texture is only significantly effective for certain conditions, and motion parallax, in line with previous results, is inconclusive to determine depth judgement accuracy for egocentrically viewed DVEs. Results also show that exocentric views, incorporating relative height and motion parallax visual cues, are effective for precise depth judgements made in DVEs. The results help us to understand the effects of certain visual depth cues to support the perception of frames of references and precise depth judgements, suggesting that the visual depth cues employed to create frames of references in DVEs may influence how effectively precise depth judgements are undertaken.     

The Immersive Virtual Environment of the digital fulldome: Considerations of relevant psychological processes

One of the most recent additions to the range of Immersive Virtual Environments has been the digital fulldome. However, not much empirical research has been conducted to explore its potential and benefits over other types of presentation formats. In this review we provide a framework within which to examine the properties of fulldome environments and compare them to those of other existing immersive digital environments. We review the state-of-the-art of virtual reality technology, and then survey core areas of psychology relevant to experiences in the fulldome, including visual perception, attention, memory, social factors and individual differences. Building on the existing research within these domains, we propose potential directions for empirical investigation that highlight the great potential of the fulldome in teaching, learning and research.     

Preemptive RANSAC for live structure and motion estimation

A system capable of performing robust live ego-motion estimation for perspective cameras is presented. The system is powered by random sample consensus with preemptive scoring of the motion hypotheses. A general statement of the problem of efficient preemptive scoring is given. Then a theoretical investigation of preemptive scoring under a simple inlier–outlier model is performed. A practical preemption scheme is proposed and it is shown that the preemption is powerful enough to enable robust live structure and motion estimation.Prepared through collaborative participation in the Robotics Consortium sponsored by the U.S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0012. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. David Nistér received PhD degree in computer vision, numerical analysis and computing science from the Royal Institute of Technology (KTH), Stockholm, Sweden, with the thesis ‘Automatic Dense Reconstruction from Uncalibrated Video Sequences’. He is currently an assistant professor at the Computer Science Department and the Center for Visualization and Virtual Environments, University of Kentucky, Lexington. Before joining UK, he was a researcher in the Vision Technologies Laboratory, Sarnoff Corporation, Princeton, and Visual Technology, Ericsson Research, Stockholm, Sweden. His research interests include computer vision, computer graphics, structure from motion, multiple view geometry, Bayesian formulations, tracking, recognition, image and video compression. He is a member of the IEEE and American Mensa.     

A pipeline virtual environment architecture for multicore processor systems

We present a novel architecture to develop Virtual Environments (VEs) for multicore CPU systems. An object-centric method provides a uniform representation of VEs. The representation enables VEs to be processed in parallel using a multistage, dual-frame pipeline. Dynamic work distribution and load balancing is accomplished using a thread migration strategy with minimal overhead. This paper describes our approach, and shows it is efficient and scalable with performance experiments. Near linear speed-ups have been observed in experiments involving up to 1,000 deformable objects on a six-core i7 CPU. This approach’s practicality is demonstrated with the development of a medical simulation trainer for a craniotomy procedure.     

A simulation modelling tool for Distributed Virtual Environments

Distributed Virtual Environments simulate the behaviour and activities of a great number of users interacting in a virtual world over a wide area network. The size of the virtual worlds and the tremendous number of users that these environments are called to support require additional bandwidth and computational resources. For supporting large-scale Distributed Virtual Environments, extended infrastructure is needed in terms of both hardware and software. However, both researchers and application designers do not always have access to such an extended infrastructure and the assessment and evaluation of developed performance improvement techniques becomes extremely difficult. To address this issue, this paper presents a simulation modelling tool, called STEADiVE for networked servers Distributed Virtual Environments that could be used by designers for evaluating the performance of their approaches under different scenarios and system settings. The validation of the simulation modelling tool has showed that it achieves high accuracy in representing a real DVE system. STEADiVE comes to fill in the gap in the area of simulation tools for these systems.     

Jim Blinn's corner-a trip down the graphics pipeline: line clipping

The standard computer graphics transform-clip-draw pipeline is described, and an overview of the clipping function is given. A simple algorithm for performing line clipping is presented. Homogeneous clipping, Z clipping, and global clipping using the algorithm are discussed     

Realizing 3D Visual Programming Environments within a Virtual Environment

In the visual programming community, many interesting graphical metaphors have been reported upon for representing computer programs graphically. Most of them have a 2D or 2.5D appearance on the screen in order to reflect the inherent multi-dimensionality of the programming constructs being represented. By going into a three-dimensional representation, this reflection can go a stepfurther. With ever increasing3D graphics rendering capabilities on todays computers, it moreover becomes feasible to extend the dimensionality of the program (and data structure) depiction. We follow this approach by realizing 3D graphical programming techniques within CAEL, our interactive Computer Animation Environment Language. The paper elucidates how several concepts, traditionally found within the Virtual Environments area, can be utilized in the realization of three-dimensional Programming Environments.     

Three views of virtual reality: nonimmersive virtual reality

Nonimmersive virtual reality (VR), which places the user in a 3D environment that can be directly manipulated with a conventional graphics workstation using a monitor, a keyboard; and a mouse, is discussed. The scene is displayed with the same 3D depth cues used in immersive VR: perspective view, hidden-surface elimination, color, texture, lighting, shading and shadows. As in immersive VR, animation and simulation are interactively controlled in response to the user's direct manipulation. Much of the technology used to support immersive and nonimmersive VR is the same. They use the same 3D modeling and rendering and many of the same interaction techniques. The advantages and applications of nonimmersive VR systems are discussed. Immersive and nonimmersive VR systems are compared and hybrid possibilities are reviewed     

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.     

用OpenGL开发虚拟制造环境(二)

本文介绍ＯｐｅｎＧＬ３Ｄ图形处理的管道过程,从建立模型坐标、视平面坐标到设备视风变换。论述了ＯｐｅｎＧＬ在虑拟制造环境开发实践中的应用。     

The effects of movement of attractors and pictorial content of rewards on users' behaviour in virtual environments: an empirical study in the framework of perceptual opportunities

Technological developments in Virtual Reality (VR) appear to outpace progress in design methodology of VR. The theory of Perceptual Opportunities (POs) has previously been proposed as a basis of such a design methodology (Blade and Padgett, 2002). This paper presents the first empirical study investigating the effect of representation of POs on users' behaviour in Virtual Environments (VEs). The current study has a methodological focus, using POs as a framework and desktop VR as a experimental environment. The application of an experimental paradigm is illustrated with two experiments. Evidence was found for an effect of movement type on choice of objects in a simple VE. Implications for VE design and the methodology of empirical research in the framework of POs are discussed.     

Walking in a cube: novel metaphors for safely navigating large virtual environments in restricted real workspaces

Immersive spaces such as 4-sided displays with stereo viewing and high-quality tracking provide a very engaging and realistic virtual experience. However, walking is inherently limited by the restricted physical space, both due to the screens (limited translation) and the missing back screen (limited rotation). In this paper, we propose three novel locomotion techniques that have three concurrent goals: keep the user safe from reaching the translational and rotational boundaries; increase the amount of real walking and finally, provide a more enjoyable and ecological interaction paradigm compared to traditional controller-based approaches. We notably introduce the "Virtual Companion", which uses a small bird to guide the user through VEs larger than the physical space. We evaluate the three new techniques through a user study with travel-to-target and path following tasks. The study provides insight into the relative strengths of each new technique for the three aforementioned goals. Specifically, if speed and accuracy are paramount, traditional controller interfaces augmented with our novel warning techniques may be more appropriate; if physical walking is more important, two of our paradigms (extended Magic Barrier Tape and Constrained Wand) should be preferred; last, fun and ecological criteria would favor the Virtual Companion.     

一种双目立体视觉算法的GPU实现

利用可编程图形硬件GPU实现了非参数局域变换双目立体视觉算法。该算法使用局部非参数统计的结果而不是像素灰度值作为匹配代价，相对于其它基于区域的立体匹配算法，具有物体边界区域处理稳定和适于硬件实现等优点。该文利用GPU的最新特性实现了算法的全部运算都在GPU上执行。由于GPU的并行流水特性，算法在GPU上的运算速度较在CPU上得到提高。