We present in this article a parallelization of a discrete radiosity method, based on scene division and achieved on a cluster of workstations. This method is based on discretization of surfaces into ...voxels and not into patches like most of the radiosity methods do. Voxels are stocked into visibility lists representing the space partition into discrete lines and allowing mutually visible neighbour voxels to exchange their radiosities. The parallelization distributes the scene among the processors by dividing it into parts. Exchanges of radiosity values are accomplished between neighbourhood voxels belonging to a same list but located on different processors. This parallelization improved time and distributed memory offering thus the capability to deal with large scenes.
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The current trend in hardware for parallel rendering is to use clusters instead of high-end super computer. We describe a novel parallel rendering system that allows application to render to a ...large-scale display. Our system, called D3DPR, uses a cluster of PCs with high-performance graphics accelerators to drive an array of projectors. D3DPR consists of two types of logical nodes, Geometry Distributing Node and Geometry Rendering Node. It allows existing Direct3D9 application to run on our parallel system without any modification. The advantage of high-resolution and high-performance can be obtained in our system, especially when the triangle number of the application becomes very large. Moreover, the details of interconnecting network architecture, data distribution, communication and synchronization, etc. are hidden from the users.
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Although the sort-last parallel rendering is a promising approach to accelerate large-scale computer graphics applications handling huge data sets, parallel image composition is a bottleneck of ...performance improvement. So far, several image coding schemes have been proposed in order to achieve fast image composition by compressing communicated data. These schemes mainly encode blank pixels in rendered images, which are pixels with no projection of objects. However, sufficient compression was not available in the case that rendered images have few blank pixels. This paper presents an image coding scheme that reduces the communication time in parallel image composition by effective compression of non-blank pixels and load balancing. The coding scheme exploits coherence of differential pixel values with a few additional computations that do not spoil the reduction in communication time. Experiments on a PC cluster with eight processing elements connected by a 100 Mbit Ethernet switching hub show that the worst frame rate of all viewing parameters can greatly be improved by the proposed coding scheme.
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Parallel rendering algorithms usually suffer from high load imbalance during execution, due to the irregular nature of the datasets. In this paper, we propose a new load balancing scheme for ...tile-based parallel rendering that includes strategies for load estimation, tile decomposition and tile assignment. The load estimation strategy computes the rendering cost for each pixel, and uses it as a prediction for the next frame. The tile decomposition strategy adaptively divides the screen into tiles based on the computed costs, until an evenly tile partition is achieved. The tile assignment strategy distributes the tiles among rendering processors, based on a 2-optimal scheduling. Experimental results show that our scheme achieves significant performance gains by reducing the load imbalance when compared to the traditional tile subdivision and static random distribution schemes.
Large-scale and high-resolution displays are increasingly being used 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.
We are investigating how to build such a system using only inexpensive commodity components in a PC cluster. The main challenge is to develop scalable algorithms to partition and distribute rendering tasks effectively under the bandwidth, processing, and storage constraints of a distributed system. In this paper, we compare three different approaches that differ in the type of data transmitted from client to display servers: control, primitives, or pixels. For each approach, we describe our initial experiments with a working prototype system driving a multi-projector display wall with a PC cluster. We find that different approaches are suitable for different system architectures, with the best choice depending on the communication bandwidth, storage capacity, and processing power of the clients and display servers.
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We present an efficient occlusion culling algorithm for interactive rendering of large complex virtual scene with high depth complexity. Our method exploits both spatial and temporal coherence of ...visibility. A space hierarchy of scene is constructed and its nodes are rendered in an approximate front-to-back order. Nodes in view frustum are inserted into one of layered node lists, called layered buffers(LBs), according to its distance to the view point. Each buffer in the LBs is rendered with hardware occlusion queries. Using a visibility predictor(VP) for each node and interleaving occlusion queries with rendering, we reduce the occlusion queries count and graphics pipeline stalls greatly. This occlusion culling algorithm can work in a conservative way for high image quality rendering or in an approximate way for time critical rendering. Experimental results of different types of virtual scene are provided to demonstrate its efficiency and generality.
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This paper presents a distributed rendering system for visualization of massive molecular data sets on computational grids. It is designed with the ability to animate molecular dynamics (MD) ...simulation trajectories imported from a simulation engine in a distributed environment. MD simulation and visualization are computationally intensive tasks and computational grids are promising technologies for these applications. The framework of the system is introduced and the grid technologies and the parallel rendering approach are discussed in this paper.
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Sort-last parallel rendering is a good rendering scheme on distributed memory multiprocessors. This paper presents an improvement on the binary-swap (BS) method, which is an efficient image ...compositing algorithm for sort-last parallel rendering. Our compositing method uses three acceleration techniques, compared to the original BS method: (1) the interleaved splitting, (2) multiple bounding rectangle, and (3) run-length encoding. Through the use of the three techniques, our method balances the compositing workload among processors, exploits more sparsity of the image, and reduces the cost of communication.
We also show some experimental results on a PC cluster. The results show that our method completes the image compositing faster than the original BS method, and its speedup to the original increases with the number of processors.
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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. 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 an overview of the parallel rendering field, encompassing both hardware and software systems. The focus is on the underlying concepts and the issues which arise in the design of parallel renderers. We examine the different types of parallelism and how they can be applied in rendering applications. Concepts from parallel computing, such as data decomposition and load balancing, are considered in relation to the rendering problem. Our survey explores a number of practical considerations as well, including the choice of architectural platform, communication and memory requirements, and the problem of image assembly and display. We illustrate the discussion with numerous examples from the parallel rendering literature, representing most of the principal rendering methods currently used in computer graphics.
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We present an adaptive dynamic load balancing scheme for 3D texture based sort-last parallel volume rendering on a PC cluster equipped with GPUs. Our scheme exploits not only task parallelism but ...also data parallelism during rendering by combining the hierarchical data structures (octree and parallel BSP tree) in order to skip empty regions and distribute proper workloads to rendering nodes. Our scheme can also conduct a valid parallel rendering and image compositing in visibility order by employing a 3D clustering algorithm. To alleviate the imbalance when the transfer function is changed, a load rebalancing is inexpensively supported by exchanging only needed data. A detailed performance analysis is provided and scaling characteristics of our scheme are discussed. These show that our scheme can achieve significant performance gains by increasing parallelism and decreasing synchronizing costs compared to the traditional static distribution schemes.
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