Emerging Web graphics standards and technologies

Migrating computer graphics to the Web poses several problems, but with new standards and technology advances, graphics applications can balance latency and bandwidth constraints with image quality. The paper discusses Web graphics standards, distributed virtual environments and virtual humans.     

GPU-based real-time acoustical occlusion modeling

In typical environments, the direct path between a sound source and a listener is often occluded. However, due to the phenomenon of diffraction, sound still reaches the listener by “bending” around an obstacle that lies directly in the line of straight propagation. Modeling occlusion/diffraction effects is a difficult and computationally intensive task and thus generally ignored in virtual reality and videogame applications. Driven by the gaming industry, consumer computer graphics hardware and the graphics processing unit (GPU) in particular, have greatly advanced in recent years, outperforming the computational capacity of central processing units. Given the affordability, widespread use, and availability of computer graphics hardware, here we describe a computationally efficient GPU-based method that approximates acoustical occlusion/diffraction effects in real time. Although the method has been developed primarily for videogames where occlusion/diffraction is typically overlooked, it is relevant for dynamic and interactive virtual environments as well.     

虚拟环境的系统设计方法及计算模型研究

面向对象技术和面向Ａｇｅｎｔ技术是虚环境系统的基本设计方法。本文用面向对象的方法来构造Ａｇｅｎｔ,并提供一组支撑Ａｇｅｎｔ的底层计算模型,如神经网络,遗传算法,专家系统和规划管理等。     

An overview of physically-based modelling techniques for virtual environments

A class of virtual environments is concerned with the representation of behaviour that is apparent in the real world. In order to model this behaviour, sophisticated physical models are required. The development of these models, classed asphysically-based modelling, is based upon the fundamental concepts of Newtonian dynamics. Considerable research into physically-based modelling has already been conducted by the computer graphics community, permitting realistic animation of object motion. The application of physical models to virtual environments poses further problems, not least that of real-time execution in a fully interactive environment. This paper gives an overview of the existing computer graphics research concerned with physically-based modelling, discussing the merits and problems of various techniques in terms of the requirements of virtual environment.     

Evaluation of a low-cost 3D sound system for immersive virtual reality training systems

Since head mounted displays (HMD), datagloves, tracking systems, and powerful computer graphics resources are nowadays in an affordable price range, the usage of PC-based "virtual training systems" becomes very attractive. However, due to the limited field of view of HMD devices, additional modalities have to be provided to benefit from 3D environments. A 3D sound simulation can improve the capabilities of VR systems dramatically. Unfortunately, realistic 3D sound simulations are expensive and demand a tremendous amount of computational power to calculate reverberation, occlusion, and obstruction effects. To use 3D sound in a PC-based training system as a way to direct and guide trainees to observe specific events in 3D space, a cheaper alternative has to be provided, so that a broader range of applications can take advantage of this modality. To address this issue, we focus in this paper on the evaluation of a low-cost 3D sound simulation that is capable of providing traceable 3D sound events. We describe our experimental system setup using conventional stereo headsets in combination with a tracked HMD device and present our results with regard to precision, speed, and used signal types for localizing simulated sound events in a virtual training environment     

A transatlantic research and development environment [3D virtualgraphics]

Distributed 3D virtual environments can help researchers conduct experiments globally with remotely located participants. We discuss challenges and opportunities for the shared work environment. Our world is entering an age where our current understanding of telecommunications and graphics computing is constantly challenged. With the availability of global information highways, 3D graphical intercontinental collaboration will become a part of our daily work routine. Already, world class auto makers are attempting to reduce car development time to two-year cycles, enlisting global engineering teams. However, this process requires new tools such as shared 3D CAD and distributed product data management systems. The Fraunhofer Center for Research in Computer Graphics (CRCG) in the United States and the Fraunhofer Institute for Computer Graphics (IGD) in Germany, are looking ahead into this new age by establishing a transcontinental computer graphics research effort and a proposed G-7 testbed. We are studying how 3D computer graphics and virtual environments can aid global collaborative work. We have focused our research efforts on determining how computer networks can transform the distributed workplace into a shared environment, allowing real time interaction among people and processes without regard to their location     

A new approach for the real-time simulation of tissue deformations in surgery simulation

Simulation of the behaviour of elastic objects in real time is one of the present objectives of computer graphics. One of its fields of application lies in virtual reality, mainly in surgery simulation systems. Models used for the construction of objects with deformable behaviour in computer graphics are known as deformable models. These have two conflicting characteristics: interactivity and movement realism. The deformable models developed up till now have promoted one characteristic to the detriment of the other. In this paper, a new approach is proposed based on boundary element methods (BEM). This is characterised by a positive equilibrium between speed and realism and great robustness. These properties along with the experimental results described in this paper permit one to assert that establishing deformable models with BEM is a reliable method to model objects in virtual reality environments for surgery simulation. In addition to that, the required elasticity parameters could be obtained experimentally through the use of a pig's liver.     

Creating Real-Time Embodied Autonomous Agents

A challenging research area for computer graphics and virtual environments (VE) is training interpersonal interactions. In such a system, at least one person is the VE participant, while several more virtual human agents (represented by human-like, embodied models) are engaged in activities in the same virtual space. The participants, whether live or virtual, should interact as if all were real. This means that the virtual agents must have several characteristics afforded to real people, including the following:     

基于边折叠的网格简化算法研究

在计算机图形学和几何造型中,物体表面常用多边形网格模型来描述.一个复杂的场景可能会包含大量的多边形,不利于存储、传输及绘制.网格简化技术用于处理计算机图形学领域中广泛使用的多边形网格数据,主要应用领域有科学可视化、实时显示和虚拟现实等.文章给出了网格简化方法的分类,研究了基于边折叠的简化算法,对相关技术及其特点进行了介...     

Subregion graph: A path planning acceleration structure for characters with various motion types in very large environments

Computational Visual Media - Modern computer graphics applications commonly feature very large virtual environments and diverse characters which perform different kinds of motions. To accelerate...     

南瓜果实生长的几何造型

引入了一个虚拟瓜果结构生长模型.通过对良种南瓜的生长观察,建立其生长时期三个阶段的数学模型,并在计算机中连续、动态地模拟这三个阶段的生长过程.该模型为虚拟农作物提供了具有实际应用价值的研究方法.     

Internetworked graphics and the Web

Although the networking and computer graphics fields are considered to be distinct disciplines, they must begin to converge in order to support collaborative exploration and information visualization on the Internet and the World Wide Web. Telecommunication breakthroughs remove bottlenecks and provide new opportunities for interactive 3D graphics across globally interconnected, dissimilar networks. Multicast backbone tools, developed in the networking arena, provide desktop videoconferencing tools for sharing information visualization and virtual reality explorations. The Virtual Reality Modeling Language (VRML), developed in the computer graphics arena, supports the 3D display and fly-through of networked computing resources on the Internet. The computer graphics community considers VRML to be an interactive tool for exploring content on the Web. The telecommunications community calls it an application on the networking infrastructure. The authors define the concept of internetworked graphics to describe the future merger and dependencies of computer graphics applications and the telecommunications networking infrastructure     

Behavioral Self-Organization in Lifelike Synthetic Agents

Modern computer graphics technology has enjoyed rapid development in recent years, attracting researchers and practitioners to explore a wide spectrum of applications ranging from computer-aided graphical design to artificial life and virtual reality. This paper is concerned with the animation-based entertainment use of computer graphics, i.e., to create digitally synthetic agents that can self-animate themselves, adapt to their virtual environments, and learn new behaviors to attain some specific goals. Here we propose a synthetic agent computational architecture called inter-threaded motif-based behavioral self-organization architecture, in which one motif acquires a conditioned association from the presently sensed state of the environment to the requirement of a desired motion as well as a plausible behavioral pattern to enable such a motion, whereas another computes the optimal parameters for the identified behavior in fulfilling the motion requirement. This architecture will enable animated behaviors to be automatically programmed based on the concurrent self-organization of individual motifs as well as their crisscrossing interactions.     

Real-time deformable models for surgery simulation: a survey

Simulating the behaviour of elastic objects in real time is one of the current objectives of computer graphics. One of its fields of application lies in virtual reality, mainly in surgery simulation systems. In computer graphics, the models used for the construction of objects with deformable behaviour are known as deformable models. These have two conflicting characteristics: interactivity and motion realism. The different deformable models developed to date have promoted only one of these (usually interactivity) to the detriment of the other (biomechanical realism). In this paper, we present a classification of the different deformable models that have been developed. We present the advantages and disadvantages of each one. Finally, we make a comparison of deformable models and perform an evaluation of the state of the art and the future of deformable models.     

Web-based learning in the computer-aided design curriculum

Abstract This study attempts to apply the principle of constructivism and virtual reality (VR) technologies to computer-aided design (CAD) curriculum by integrating network, CAD and VR into a web-based learning environment. Through VR technologies, it is expected that the traditional two-dimensional (2D) computer graphics course can be expanded into a three-dimensional (3D) real-time simulation one. VR technologies provide a novel method to enhance user visualisation of complex three-dimensional graphics and environments. Experience and environmental interaction allow users more readily to perceive the dimensional interrelations of graphics which are typically portrayed through static multiview or pictorial representations. A web-based learning system ( WebDeGrator ) has been developed to simulate a computer graphics learning system for learning. Future developments of the proposed web-based learning framework are also discussed.     

Future multimedia user interfaces

No matter how powerful or elegant the technologies underlying multimedia computing, it is the user interface that ultimately determines how these systems will be used. We provide an overview of two emerging areas of user-interface research that will play major roles in future multimedia systems: virtual environments and ubiquitous computing. We discuss what they are and why they are important, and describe their relationship to current multimedia systems. While mouse and window-based user interfaces provide access to 2D graphics, video, and sound, virtual environments not only involve interactive 3D graphics, but further address all our senses through the use of spatial audio, haptics, and other modalities. While it is still a research goal to provide high-throughput video on demand, ubiquitous computing will require that multimedia network infrastructure also support extremely low-latency interaction among large numbers of mobile wireless users. To arrive at an understanding of the needs, capabilities, and potential of these new paradigms, we introduce their terminology and technology, and explain the basic system architectures being explored, leading up to a discussion of key current research issues and future directions.     

碰撞检测中的固定方向凸包包围盒的研究

碰撞检测在计算机图形学、CAD、仿真、虚拟现实等领域都有重要的研究意义.包围盒层次是解决碰撞检测问题固有的时间复杂性的一个有效途径.论述了用固定方向凸包(fixeddirectionshulls,简称FDH)作为包围盒进行碰撞检测的方法,证明了固定方向凸包适用于复杂环境中的精确碰撞检测,包括软体对象环境中的碰撞检测,并通过实验数据与其他包围盒进行了性能分析与比较.