High-resolution multiprojector display walls

Meeting the demands of the current tera-scale visualization community requires the use of large- and small-scale tiled displays. The Lawrence Livermore National Laboratory (LLNL) efforts in this area have led to the creation of one of the largest interactive tiled displays built to date, and a number of new efforts for “personal” tiled displays. Visualization hardware and software now being built will display up to 15 times the number of pixels in a typical desktop display. We outline the system implemented at LLNL for the creation and support of large, tiled, multi-pipe graphics displays. The system builds on a simple, portable, parallel API for tiling OpenGL commands in parallel to multiple contexts on a set of X servers. This API has allowed us to retrofit existing visualization and analysis codes to support these displays with very little effort. While this work represents a first step toward the ultimate goal of scalable visualization in individual office spaces, the result has been the creation of useful new visualization workspaces and tools for our users     

GPU rendering for tiled multi-projector autostereoscopic display based on chromium

In this paper, a GPU-based high-resolution multiview rendering approach (HRMVRA) is presented and incorporated into Chromium, and then a tiled multi-projector autostereoscopic display system (TMPADS) based on HRMVRA is constructed to provide an immersing 3D perception and a compelling sense of presence without the need of glasses for viewers. HRMVRA renders the multiview images in real time in only one pass, though the traditional multiview rendering approaches based on Chromium render the multiviews in multiple passes. The hardware of the autostereoscopic display system consists of a front-projection screen that covers an area of 360×160 square centimeters, twenty four projectors and thirteen computers connected with the gigabit Ethernet. TMPADS is well scalable since both the resolution and the number of the rendered views are configurable. It is shown by the experiments that HRMVRA has more than five times performance of the traditional high-resolution multiview parallax rendering based on Chromium. Most existing single-view OpenGL applications (e.g., some games like Quake III) can run directly on TMPADS without any source-code modification or re-compiling.     

基于OSG的镜面反射特效的实现

针对虚拟现实领域中如何提高渲染性能的问题,提出采用OSG(Open Scene Graph)图形开发接口实现镜面反射特效.由于镜面反射特效中的反射映像需通过绘制被反射物体的镜像拷贝来实现,而OSG的场景图技术支持对象实例的重用,它可以在一次加载几何体模型的情况下,给模型添加多个父节点,用以绘制不同状态的模型.同时,OSG采用StateSet类管理渲染状态,每个StateSet对象可以自动优化状态设置,使状态转变量最小,从而提升渲染性能.实验证明,用OSG开发库可以快速模拟出真实的镜面反射现象,并有效避免了冗余状态的设置.     

The perceptual scalability of visualization

Larger, higher resolution displays can be used to increase the scalability of information visualizations. But just how much can scalability increase using larger displays before hitting human perceptual or cognitive limits? Are the same visualization techniques that are good on a single monitor also the techniques that are best when they are scaled up using large, high-resolution displays? To answer these questions we performed a controlled experiment on user performance time, accuracy, and subjective workload when scaling up data quantity with different space-time-attribute visualizations using a large, tiled display. Twelve college students used small multiples, embedded bar matrices, and embedded time-series graphs either on a 2 megapixel (Mp) display or with data scaled up using a 32 Mp tiled display. Participants performed various overview and detail tasks on geospatially-referenced multidimensional time-series data. Results showed that current designs are perceptually scalable because they result in a decrease in task completion time when normalized per number of data attributes along with no decrease in accuracy. It appears that, for the visualizations selected for this study, the relative comparison between designs is generally consistent between display sizes. However, results also suggest that encoding is more important on a smaller display while spatial grouping is more important on a larger display. Some suggestions for designers are provided based on our experience designing visualizations for large displays.     

Tiled++: An Enhanced Tiled Hi-Res Display Wall

In recent years, high-resolution displays have become increasingly important to decision makers and scientists because large screens combined with a high pixel count facilitate content rich, simultaneous display of computer-generated imagery and high-definition video data from multiple sources. Tiled displays are attractive due to their extended screen real estate, scalability, and low cost. LCD panels are usually preferred over projectors because of their superior resolution. One of the drawbacks of LCD-based tiled displays is the fact that users sometimes get distracted by the screens' bezels, which cause discontinuities in rendered images, animations, or videos. Most conventional solutions either ignore the bezels and display all pixels, causing objects to become distorted, or eliminate the pixels that would normally fall under the bezels, causing pixels to be missing in the display of static images. In animations, the missing pixels will eventually reappear when the object moves, providing an experience that is similar to looking through a French window. In this paper, we present a new scalable approach that leads neither to discontinuities nor to significant loss of information. By projecting onto the bezels, we demonstrate that a combination of LCD-based tiled displays and projection significantly reduces the bezel problem. Our technique eliminates ambiguities that commonly occur on tiled displays in the fields of information visualization, visual data analysis, human-computer interaction, and scientific data display. It improves the usability of multimonitor systems by virtually eliminating the bezels. We describe a setup and provide results from an evaluation experiment conducted on a 3 times 3 and on a 10 times 5 tiled display wall.     

医学三维图像显示平台的开发与研究

在医疗辅助诊断软件系统中,三维显示越来越重要。文章研究并开发了一种适用于医学图像三维显示的图形平台。该平台基于场景图的概念架构,取名为SceneGraph。该平台采用OpenGL作为图形硬件接口,提供了多种交互功能。该平台目前在多个项目中都获得了应用。     

Introduction to building projection-based tiled display systems

This tutorial introduces the concepts and technologies needed to build projector-based display systems. Tiled displays offer scalability, high resolution, and large formats for various applications. Tiled displays are an emerging technology for constructing semi-immersive visualization environments capable of presenting high-resolution images from scientific simulation. The largest impact may well arise from using large-format tiled displays as one of possibly multiple displays in building information or active spaces that surround the user with diverse ways of interacting with data and multimedia information flows. These environments may prove the ultimate successor to the desktop metaphor for information technology work. Several fundamental technological problems must be addressed to make tiled displays practical. These include: the choice of screen materials and support structures; choice of projectors, projector supports, and optional fine positioners; techniques for integrating image tiles into a seamless whole; interface devices for interaction with applications; display generators and interfaces; and the display software environment     

Equalizer: A Scalable Parallel Rendering Framework

Continuing improvements in CPU and GPU performances as well as increasing multi-core processor and cluster-based parallelism demand for flexible and scalable parallel rendering solutions that can exploit multipipe hardware accelerated graphics. In fact, to achieve interactive visualization, scalable rendering systems are essential to cope with the rapid growth of data sets. However, parallel rendering systems are non-trivial to develop and often only application specific implementations have been proposed. The task of developing a scalable parallel rendering framework is even more difficult if it should be generic to support various types of data and visualization applications, and at the same time work efficiently on a cluster with distributed graphics cards. In this paper we introduce a novel system called Equalizer, a toolkit for scalable parallel rendering based on OpenGL which provides an application programming interface (API) to develop scalable graphics applications for a wide range of systems ranging from large distributed visualization clusters and multi-processor multipipe graphics systems to single-processor single-pipe desktop machines. We describe the system architecture, the basic API, discuss its advantadges over previous approaches, present example configurations and usage scenarios as well as scalability results.     

虚拟现实中粒子系统的设计与应用

该文描述了一套粒子系统应用程序接口(API)的设计，并将其作为一个模块应用于虚拟现实系统的动态场景模拟中。该粒子系统API采用合理的数据结构，设计了一套高效的粒子生成、管理方法，并采用高速OpenGL渲染引擎，使之能够满足在普通PC机上模拟大数据量动态场景的需求。同时，它还具有相当的灵活性和可扩展性，可以应用于各种各样的动态场景。这套粒子系统API的设计充分体现了面向对象和结构化程序设计的思想，在传统算法上进行优化创新，使之能更好地达到虚拟现实的效果。     

三维多元地学数据一体化显示框架设计

随着三维地质信息系统发展与应用的深入,对地学数据的可视化需求更加迫切。采用面向对象的思想设计并实现了一个可扩展的多元地学数据一体化显示框架。该框架主要划分为模型层、场景层和渲染层,使得数据与绘制流程分离。围绕此框架详细阐述了绘制管线、绘制过程的设计和多层次地学场景组织,满足地质多领域、多专题数据的统一显示与分析需要。基于此框架在OpenGL环境下开发了北京市三维城市地质信息管理与服务系统。     

基于OSG的飞行视景仿真平台开发

OSG(Open Scene Graph)是一个出色的视景仿真开源软件包,基于OSG可以开发高拟真度低费用的飞行视景过程.但是由于OSG是基础类库,因而有必要对其进行二次开发以降低视景过程的开发难度和开发周期.首先论述了OSG的体系结构,并依据装配式的视景仿真生成思想,设计了基于OSG的飞行视景仿真软件平台FSS的顶层结构体系.基于该顶层设计,实现了软件的开发,通过示例可以看出,在FSS上可以简单、快速实现飞行视景过程的创建,从而大幅度降低了飞行视景仿真过程开发的周期和难度.     

基于OSG的电子沙盘系统的研究与实现

结合“山西省水利工程规划电子沙盘”实例提供了一种基于开源跨平台三维渲染引擎OSG的电子沙盘系统开发方案,并对其中场景结构的组织和管理、大地形建模和立体显示等关键技术展开了研究.分析了地形建模工具VPB的工作机理及生成IVE模型的分页细节层次结构,提出了一种模拟飞行的场景切换模式的实现方法.所开发出的系统具有海量模型库迅速加载、矢量文字图片显示、多种场景漫游方式并存等特点,对于工程实践有一定的指导意义.     

基于OSG与Qt的FAST三维场景仿真

为解决FAST基地可视化的问题,开发了一套基于OpenSceneGraph(OSG)与Qt的三维场景仿真系统。通过三维建模,计算机程序自动化布局,OSG虚拟场景搭建等,将FAST的场景进行仿真显示。通过数据驱动实现对虚拟场景的实时更新,同时采用OSG的粒子系统来模拟雨雪天气特效场景。该系统将FAST的场景实时显现在技术工作人员面前,具有场景漫游,动态演示等基本人机交互功能,可为FAST基地的实践工作提供辅助决策依据。     

基于OpengL的面向对象的巷道三维可视化

介绍了巷道三维模型建立的过程,即巷道数据处理、巷道三维实体模型、模型OpengL映射、三维场景设置、坐标投影变换、巷道三维显示。采用面向对象的VC++的结构体数据类型和类建立描述组成巷道中心线的不同基本元素空间信息的数据结构。利用OpenGL原语进行描述,对巷道实体三维数学建模。通过三维场景设置,控制三维巷道的生成效果,运用OpenGL的Z缓存自动消隐功能构建和生成具有真实感的三维巷道模型,并实现交互式查询。以此解决方案对地下巷道的实际情况进行直观和形象的模拟,对煤矿的信息化管理能力有一定的提高,利于指导煤矿的实际生产。     

A scalable distributed paradigm for multi-user interaction with tiled rear projection display walls

We present the first distributed paradigm for multiple users to interact simultaneously with large tiled rear projection display walls. Unlike earlier works, our paradigm allows easy scalability across different applications, interaction modalities, displays and users. The novelty of the design lies in its distributed nature allowing well-compartmented, application independent, and application specific modules. This enables adapting to different 2D applications and interaction modalities easily by changing a few application specific modules. We demonstrate four challenging 2D applications on a nine projector display to demonstrate the application scalability of our method: map visualization, virtual graffiti, virtual bulletin board and an emergency management system. We demonstrate the scalability of our method to multiple interaction modalities by showing both gesture-based and laser-based user interfaces. Finally, we improve earlier distributed methods to register multiple projectors. Previous works need multiple patterns to identify the neighbors, the configuration of the display and the registration across multiple projectors in logarithmic time with respect to the number of projectors in the display. We propose a new approach that achieves this using a single pattern based on specially augmented QR codes in constant time. Further, previous distributed registration algorithms are prone to large misregistrations. We propose a novel radially cascading geometric registration technique that yields significantly better accuracy. Thus, our improvements allow a significantly more efficient and accurate technique for distributed self-registration of multi-projector display walls.     

超高分辨GIS信息显示技术

为解决海量 GIS 地图信息显示分辨率高、处理难度大等问题,研究了集群并行显示、WMS 服务、GIS渲染显示等技术,提出了以计算机集群并行计算为基础构建集群并行 GIS 拼接显示系统,采用 WMS 并行获取GIS数据信息、地图投影变换处理数据、OpenGL并行纹理渲染,进而实现GIS数据的超高分辨显示。实验结果表明,提出的集群并行GIS拼接显示系统可极大地提高地图显示分辨率、为海量GIS地图的超高分辨显示提供了可行的解决方案。     

Ray-driven dynamic working set rendering

Ray tracing a volume scene graph composed of multiple point-based volume objects (PBVO) can produce high quality images with effects such as shadows and constructive operations. A naive approach, however, would demand an overwhelming amount of memory to accommodate all point datasets and their associated control structures such as octrees. This paper describes an out-of-core approach for rendering such a scene graph in a scalable manner. In order to address the difficulty in pre-determining the order of data caching, we introduce a technique based on a dynamic, in-core working set. We present a ray-driven algorithm for predicting the working set automatically. This allows both the data and the control structures required for ray tracing to be dynamically pre-fetched according to access patterns determined based on captured knowledge of ray-data intersection. We have conducted a series of experiments on the scalability of the technique using working sets and datasets of different sizes. With the aid of both qualitative and quantitative analysis, we demonstrate that this approach allows the rendering of multiple large PBVOs in a volume scene graph to be performed on desktop computers.     

A scalable architecture for geometric correction of multi-projector display systems

Multi-projector displays allow the realization of large and immersive projection environments by allowing the tiling of projections from multiple projectors. Such tiled displays require real time geometrical warping of the content that is being projected from each projector. This geometrical warping is a computationally intensive operation and is typically applied using high-end graphics processing units (GPUs) that are able to process a defined number of projector channels. Furthermore, this limits the applicability of such multi-projector display systems only to the content that is being generated using desktop based systems. In this paper we propose a platform independent FPGA based scalable hardware architecture for geometric correction of projected content that allows addition of each projector channel at a fractional increase in logic area. The proposed scheme provides real time correction of HD quality video streams and thus enables the use of this technology for embedded and standalone devices.