communication traffic between sortfirst processors rendering NCGA ÒheadÓ Picture-Level benchmark [1]. Arrow color indicates the number of primitives transferred between processors between these two successive frames. Range is 0 (black) to 800 (white) using a heated-object spectrum. We describe three broad classes of parallel rendering methods, based on where the sort from object-space to screen space occurs. These classes encompass most feedforward parallel software and hardware rendering architectures that have been described to date. After introducing the classes, we perform a coarse analysis of the aggregate processing and communication costs of each and identify constraints they impose on the rendering application. The aim is to provide a conceptual model of the tradeoffs between the approaches as an aid to designers and implementers of high-performance, parallel rendering systems.

Multi-projector systems are increasingly being used to provide large-scale and high-resolution displays for next-generation interactive 3D graphics applications, including large-scale data visualization, immersive virtual environments, and collaborative design. These systems must include a very high-performance and scalable 3D rendering subsystem in order to generate high-resolution images at real time frame rates. This paper describes a sort-first based parallel rendering system for a scalable display wall system built with a network of PCs, graphics accelerators, and portable projectors. The main challenge is to develop scalable algorithms to partition and assign rendering tasks effectively under the performance and functionality constrains of system area networks, PCs, and commodity 3-D graphics accelerators. We have developed three coarse-grained partitioning algorithms and incorporated them into a working prototype system. This paper describes these algorithms and reports our init...

We investigate a new hybrid of sort-first and sort-last approach for parallel polygon rendering, using as a target platform a cluster of PCs. Unlike previous methods that statically partition the 3D model and/or the 2D image, our approach performs dynamic, viewdependent and coordinated partitioning of both the 3D model and the 2D image. Using a specific algorithm that follows this approach, we show that it performs better than previous approaches and scales better with both processor count and screen resolution. Overall, our algorithm is able to achieve interactive frame rates with efficiencies of 55.0% to 70.5% during simulations of a system with 64 PCs. While it does have potential disadvantages in client-side processing and in dynamic data management---which also stem from its dynamic, view-dependent nature---these problems are likely to diminish with technology trends in the future. Keywords: Parallel rendering, cluster computing. 1 Introduction The objective of our research is ...

In computer graphics, rendering is the process by which an abstract description of a scene is converted to an image. When the scene is complex, or when high-quality images or high frame rates are required, the rendering process becomes computationally demanding. To provide the necessary levels of performance, parallel computing techniques must be brought to bear. Although parallelism has been exploited in computer graphics since the early days of the field, its initial use was primarily in specialized applications. The VLSI revolution of the late 1970Õs and the advent of scalable parallel computers during the late 1980Õs changed this situation. Today, parallel hardware is routinely used in graphics workstations, and numerous software-based rendering systems have been developed for general-purpose parallel architectures. This article provides a broad introduction to the subject of parallel rendering, encompassing both hardware and software systems. The focus is on the underlying concepts and the issues which arise in the design of parallel rendering algorithms and systems. We examine the different types of parallelism and how they can be applied in rendering applications. Concepts from parallel computing, such as data decomposition, task granularity, scalability, and load balancing, are considered in relation to the rendering

With widespread use of raster scan displays and the ever-increasing desire for faster interactivity, higher image com-plexity, and higher resolution in displayed images, several techniques have been proposed for rasterizing primitive graphical objects. This paper characterizes the performance of these techniques and shows how they evolve for more complex images on higher resolution displays. This charac-terization will not only show the strengths and deficiencies of existing rasterization techniques, but will also reveal new ar-chitectures for future raster graphics systems.

This dissertation identifies a class of parallel polygon rendering algorithms suitable for interactive use on multicomputers, and presents a methodology for designing efficient algorithms within that class. The methodology was used to design a new polygon rendering algorithm that uses the frame-to-frame coherence of the screen image to evenly partition the rasterization at reasonable cost. An implementation of the algorithm on the Intel Touchstone Delta at Caltech, the largest multicomputer at the time, renders 3.1 million triangles per second. The rate was measured using a 806,640 triangle model and 512 i860 processors, and includes back-facing triangles. A similar algorithm is used in Pixel-Planes 5, a system that has specialized rasterization processors, and which, when introduced, had a benchmark score for the SPEC Graphics Performance Characterization Group "head" benchmark that was nearly four times faster than commercial workstations. The algorithm design methodology also ident...

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Communication forms the backbone of parallel graphics, allowing multiple functional units to cooperate to render images. The cost of this communication, both in system resources and money, is the primary limit to parallelism. We examine the use of object and image parallelism and describe architectures in terms of the sorting communication that connects these forms of parallelism. We introduce an extended taxonomy of parallel graphics architecture that more fully distinguishes architectures based on their sorting communication, paying particular attention to the difference between sorting fragments after rasterization, and sorting samples after fragments are merged with the framebuffer. We introduce three new forms of communication, distribution, routing and texturing, in addition to sorting. Distribution connects object parallel pipeline stages, routing connects image parallel pipeline stages, and texturing connects untextured fragments with texture memory. All of these types of communication allow the parallelism of successive pipeline stages to be decoupled, and thus load-balanced. We generalize communication to include not only interconnect, which provides communication across space, but also memory, which functions as communication across time. We examine a number of architectures from this communicationcentric perspective, and discuss the limits to their scalability. We draw conclusions to the limits of both image parallelism and broadcast communication and suggest architectures that avoid these limitations.