This paper describes the parallel implementation of the z-buffer algorithm on a distributed memory machine. The z-buffer is one of the most popular techniques used to generate a representation of a scene consisting of...
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This paper describes the parallel implementation of the z-buffer algorithm on a distributed memory machine. The z-buffer is one of the most popular techniques used to generate a representation of a scene consisting of objects in a three-dimensional world. We propose and compare two different parallel implementations on a reconfigurable network of Transputers. In the first approach, the description of the scene is distributed among the processors configured as a tree. The picture is processed in a pipelined fashion, in order to output parts of the image during the computation of the remainder. We show the influence of the degree and the height of the tree on the global performance of the algorithm. In a second approach, both the picture and the scene description are distributed to the processors. We have therefore to redistribute dynamically the tiles among the processors at the beginning of the computation. To perform this redistribution, a special algorithm is designed for the case where the processors are configured as a unidirectional or bidirectional ring. Then we implement a greedy algorithm that enables us to perform the redistribution on an arbitrary interconnection network. We show that the two approaches are complementary: for small pictures or large scenes, a tree-based algorithm performs better than a redistribution-based algorithm, but for large pictures or smaller scenes, it is the other way round. We obtain substantial speedups over the sequential implementation, with up to 32 processors.
A novel method based on time-domain physical optics (TDPO) is proposed to determine the transient response of electrically large conducting targets which are modelled with triangular facets. TD complex source beam (TD...
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A novel method based on time-domain physical optics (TDPO) is proposed to determine the transient response of electrically large conducting targets which are modelled with triangular facets. TD complex source beam (TDCSB) is used to illuminate the complex target. Different from plane wave, the propagation direction of CSB is not a line in real space. A fast shadowing technique based on z-buffer algorithm is presented to determine the shadowed area of PO when TDCSB is adopted. Analytic time transform is utilised to investigate the analytic step response of a complex target. With an appropriate transform, the two-dimensional (2D) integral of TDPO can be reduced to 1D which is independent of electrical size. Since the tedious and time-consuming numerical integration in the conventional TDPO is avoided, this method has a significant superiority in terms of speed. Numerical results are showed in this study to demonstrate the efficiency of the proposed method.
A new 3D ray-tracing technique, based on the Angular z-buffer algorithm, [1] to speed-up reflection calculations is presented. The technique can be applied to the analysis of propagation in urban or indoor environment...
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A new 3D ray-tracing technique, based on the Angular z-buffer algorithm, [1] to speed-up reflection calculations is presented. The technique can be applied to the analysis of propagation in urban or indoor environments, or to the computation of radiation of antennas on-board complex structures amongst other applications. The technique is used in combination with the Uniform Theory of Diffraction (UTD) and shows a large reduction in CPU-time.
Interactive multimedia simulations and computer game elements can be successfully combined in order to create new advanced educational resources for teaching today's generation of students. Such a learning environ...
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Interactive multimedia simulations and computer game elements can be successfully combined in order to create new advanced educational resources for teaching today's generation of students. Such a learning environment, a game-based learning model (GBLm), has been designed as a research prototype. This paper describes one type of GBLm for computer engineering, which we have used in the subject of computer graphics for the teaching unit z-buffer algorithm, in order to facilitate the learning process. The implementation of a GBLm for graphical algorithms (GBL4CAl) is presented in detail as a multimedia interactive learning module designed to motivate students by making learning a more enjoyable process. During the design of the GBL4CAl module, special attention was paid to the integration of pedagogical and game-play aspects.
A method which simply generates evaluation data for scene flow testing is presented, in which most algorithms for scene flow estimation require a pair of depth and colour images. We scanned the 3D geometry of a real o...
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A method which simply generates evaluation data for scene flow testing is presented, in which most algorithms for scene flow estimation require a pair of depth and colour images. We scanned the 3D geometry of a real object and rendered it in graphical space to acquire its depth and colour information. Next, surface deformation to generate natural motion for the scene flow is employed. The surface deformation enabled the generation of non-rigid as well as rigid motion. Next, barycentric coefficients were exploited to compute the ground truth scene flow. The coefficients enabled the acquired dense scene to flow accurately without dense point tracking and colour information. On the other hand, each flow vector was computed per pixel and a pixel could come from more than one point due to occlusion. We compute the flow maps dividing the geometry into the front area and the occluded area by modifying a z-buffer algorithm. Experimental results showed that the proposed method reliably provided evaluation data (a pair of depth and colour images and a scene flow map) based on a scanned model with occlusion.
An efficient algorithm for data visualization is presented. Its purpose is to display the data distribution on the outside of three-dimensional (3D) unstructured grid. For speeding up the visualization procedure, two ...
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An efficient algorithm for data visualization is presented. Its purpose is to display the data distribution on the outside of three-dimensional (3D) unstructured grid. For speeding up the visualization procedure, two algorithms for classifying element surfaces of the grid into outer surfaces and inner surfaces are presented, their efficiency is discussed, and algorithm 2 based on related surfaces of the minimum (or maximum) element node number is chosen as the better one in rendering the data distribution on outer surfaces. The algorithm has higher efficiency than other algorithms available, and can be implemented easily. (C) 2002 Published by Elsevier Science Ltd.
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