Abstract not found

We present a strategy for rendering in distributed virtual environments. A geometry database is maintained by a server, while users invoke individual clients to interact with the environment. Instead of downloading a complete copy of the geometry data, the data is distributed on demand, thus gaining significant savings in network bandwidth. Our strategy combines several techniques, including levels of detail, progressive refinement and graceful degradation to deliver the data "just in time" over the network to the rendering process. The method allows operate on a tight resource budget, which important if attempting to use low cost systems for virtual reality applications.

This thesis presents a generic and principled solution for optimising the visual complexity of any arbitrary computer-generated virtual environment (VE). This is performed with the ultimate goal of reducing the inherent latencies of current virtual reality (VR) technology. Effectively, we wish to remove extraneous detail from an environment which the user cannot perceive, and thus modulate the graphical complexity of a VE with little or no perceptual artifacts. The work proceeds by investigating contemporary models and theories of visual perception and then applying these to the field of real-time computer graphics. Subsequently, a technique is devised to assess the perceptual content of a computer-generated image in terms of spatial frequency (c/deg), and a model of contrast sensitivity is formulated to describe a user's ability to perceive detail under various conditions in terms of this metric. This allows us to base the level of detail (LOD) of each object in a VE on a measure of ...

Virtual Reality (VR), sometimes called Virtual Environments (VE) has drawn much attention in the last few years. Extensive media coverage causes this interest to grow rapidly. Very few people, however, really know what VR is, what its basic principles and its open problems are. In this paper a historical overview of virtual reality is presented, basic terminology and classes of VR systems are listed, followed by applications of this technology in science, work, and entertainment areas. An insightful study of typical VR systems is done. All components of VR application and interrelations between them are thoroughly examined: input devices, output devices and software. Additionally human factors and their implication on the design issues of VE are discussed . Finally, the future of VR is considered in two aspects: technological and social. New research directions, technological frontiers and potential applications are pointed out. The possible positive and negative influence of VR on li...

: This paper considers the extension of a realtime graphics renderer to support fovea enhancement---the technique of localising visual detail to the particular region of the displaywhich the user is looking towards. This is performed by extending the standard notion of distance Level of Detail (LOD) into three dimensions to givevolumetric LOD# whereby the LOD of an object is related to its presence within a three- dimensional volume whichis aligned with the user's gaze. Before introducing this technique, some background details are discussed regarding the relevantcharacteristics of the human visual system and current solutions for effective gaze tracking. Subsequently, a brief cross-section of relevant research is presented and a conceptual model of volumetric LOD is formulated. Finally, implementation factors for such a system are considered and a theoretical evaluation is proffered. 1 Introduction Most current virtual reality (VR) graphics engines are polygon-based, i.e. all objec...

This report will present a procedure for assessing the degree of visual detail which a user can perceive in an arbitrary computer-generated image. This will involve describing an image in terms of its component spatial frequencies (c/deg)# a measure whichis commonly employed in the field of visual perception to characterise the efficacy of the human visual system. The text will present a brief introduction to this visual metric, and then demonstrate how a full-colour computer-generated image can be described in terms of this metric. The approachadvocated here is based upon an image segmentation algorithm: Fourier techniques will be considered, and shown to be inappropriate for this particular application. Keywords: Computer graphics, visual perception, visual acuity, spatial frequency. 1 Introduction For decades, the field of computer graphics has striven to produce ever-more visually realistic displays. This has seen a progression from simple, bland wireframe figures to ful...

Many real-time 3D graphics renderers represent each object as a collection of simple polygons. The complexity of this polygon structureisofpractical relevancebecause it can manifestly affect the performance of the graphics system. It is thereforecommonplace to find techniques to reduce the polygonal complexity of a model with the ultimate aim of improving the interactivity of the application. In the past, many of these schemes have not been concernedwiththeperceptual side-effects of this reduction and as a result a number of visual incongruities are often perceivable when these correspondinglyreducedrepresentations are employed. As an attempt to circumvent these problems, this paper presents a methodology for reducing the polygonal complexity of a model, whilst retaining a degreeofperceptual predictability. This allows the visual consequencesofthedegradation to be quantifiedandaccurately modelled. Keywords: polygon reduction, level of detail, visual perception, human visual s...

this paper we describe a system to show some limited effects on a static toy-car model and present techniques that can be used in similar setups. Our focus is on creating apparent motion for animation

The commonly used solution for real-life 3D model representation is polygonal spatially consistent geometry, with texture, and, optionally, bump or displacement maps attached. Although the idea of displacement mapping is well known, there are just a few approaches to its efficient implementation. In this paper we present a technique that allows for efficient representation and rendering of real-life 3D models by getting a new angle on the displacement mapping concept. We introduce a new primitive that is defined as the range image of a small part of the model’s surface; therefore, it is called a spatial patch. The whole model is just a collection of patches with no connectivity information between them. Such a representation can be directly acquired by 3D scanning machinery, and stored in a compact uniform form. It also allows for efficient visualization. In this paper we present some aspects of spatial patch rendering technique that utilize conventional z-buffer and benefit from modern features of computing units. We also discuss our experience in representing 3D models by spatial patches, provide some practical results and set up directions for future work. Our preliminary evaluation of the technique makes us believe that spatial patch technology can be efficiently used in a wide range of applications dealing with real-life 3D data.