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Load balancing methods for ray tracing and binary tree computing using PVM

parallel COMPUTING 1995年第12期21卷 1963-1978页

作者： Sekharan, CN Goel, V Sridhar, R UNIV CENT FLORIDA DEPT COMP SCIORLANDOFL 32816 UNIV OKLAHOMA SCH COMP SCINORMANOK 73019

We propose efficient load balancing methods for two computational problems namely ray tracing and bottom-up binary tree computing in a distributed environment. In the context of ray tracing, we propose a variant of a static load balancing technique presented in [15] where the sampling is based on partitioning the object space. Our approach partitions the image instead and uses an efficient scheduling technique for load balancing. Computations carried out on a binary tree arise naturally in image processing and network optimization problems. Many of these problems are solved efficiently in parallel by the popular tree contraction technique [1]. In this paper, we explore the tree-contraction technique in a distributed setting using the grain packing method [9]. Implementations of our algorithms on a cluster of workstations using parallel Virtual Machine (PVM) [6] demonstrate near-perfect load balancing.

关键词： load balancing ray tracing binary tree distributed environment PVM workstation cluster

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A distributed AND ITERATIVE METHOD FOR SQUARE-ROOT FILTERING IN SPACE-TIME ESTIMATION

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AUTOMATICA 1995年第1期31卷 67-82页

作者： CHIN, TM KARL, WC WILLSKY, AS MIT INFORMAT & DECIS SYST LABCAMBRIDGEMA 02139 MIT DEPT ELECT ENGN & COMP SCICAMBRIDGEMA 02139

We describe a distributed and iterative approach to perform the unitary transformations in the square root information filter implementation of the Kalman filter, providing an alternative to the common QR factorization-based approaches. The new approach is useful in approximate computation of filtered estimates for temporally evolving random fields defined by local interactions and observations. Using several examples motivated by computer vision applications, we demonstrate that near-optimal estimates can be computed for problems of practical importance using only a small number of iterations, which can be performed in a finely parallel manner over the spatial domain of the random field.

关键词： KALMAN FILTERS image processing MULTIDIMENSIONAL SYSTEMS MODEL REDUCTION parallel processing ITERATIVE methods

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Efficient image matching: a hierarchical chamfer matching scheme via distributed system

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Real-time imaging 1995年第4期1卷 [d]245-259页

作者： You, J. Pissaloux, E. Zhu, W.P. Cohen, H.A. Univ of South Australia

image matching has played a key role in object recognition and localization. One central problem is to find an efficient and effective approach to search for the best matching between two image sets. In contrast to the conventional matching techniques, the innovation of our method detailed in this paper is to propose a hierarchical Chamfer matching scheme based on the dynamic detection of interesting points. The algorithm extends the traditional methods by introducing interesting points to replace edge points in distance transform for the matching measurement. The search for the best matching is guided by minimizing a given matching criterion in an interesting points pyramid from coarse level to fine level. The pyramid is created through a dynamic thresholding scheme and such a hierarchical structure aims to reduce the computation load. The processing speed is further improved by parallel implementation on a low cost heterogeneous PVM (parallel Virtual Machine) network without specific software and hardware requirements. The experimental results demonstrate that our algorithm is simple to implement and quite insensitive to noise and other disturbances with reliability and efficiency.

关键词： image processing

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parallel DATA RESAMPLING AND FOURIER INVERSION BY THE SCAN-LINE METHOD

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IEEE TRANSACTIONS ON MEDICAL IMAGING 1995年第3期14卷 454-463页

作者： NOLL, DC WEBB, JA WARFEL, TE CARNEGIE MELLON UNIV SCH COMP SCIPITTSBURGHPA 15213 CARNEGIE MELLON UNIV DEPT ELECT & COMP ENGNPITTSBURGHPA 15213

Fourier inversion is an efficient method for image reconstruction in a variety of applications, for example, in computed tomography and magnetic resonance imaging. Fourier inversion normally consists of two steps, interpolation of data onto a rectilinear grid, if necessary, and inverse Fourier transformation, This paper presents interpolation by the scan-line method, in which the interpolation algorithm is implemented in a form consisting only of row operations and data transposes, The two-dimensional inverse Fourier transformation can also be implemented with only row operations and data transposes, Accordingly, Fourier inversion can easily be implemented on a parallel computer that supports row operations and data transposes on row distributed data The conditions under which the scan-line implementations are algorithmically equivalent to the original serial computer implementation are described and methods for improving accuracy outside of those conditions are presented, The scan-line algorithm is implemented on the iWarp parallel computer using the Adapt language for parallel image processing. This implementation is applied to magnetic resonance data acquired along radial-lines and spiral trajectories through Fourier transform space.

关键词： Resampling Interpolation parallel computers image reconstruction Fourier Interpolation Arithmetic Fourier Transform method of lines Inversion

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Hierarchical image matching scheme based on the dynamic detection of interesting points

Hierarchical image matching scheme based on the dynamic dete...

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Proceedings of the 1995 20th International Conference on Acoustics, Speech, and Signal processing. Part 2 (of 5)

作者： You, Jane Pissaloux, Edwige Cohen, H.A. Univ of South Australia

This paper presents a parallel approach to a hierarchical image matching scheme using the Hausdorff distance for object recognition and localization in aerial images. Unlike the conventional matching methods in which edge pixels are considered as image feature pixels in distance transform and the blind pointwise comparison procedure in terms of the Hausdorff distance is applied, a guided image matching system is developed by the hierarchical detection of interesting points via a dynamic thresholding scheme for the search of the best matching between two image sets. Furthermore, the concept of remote procedure call (RPC) in distributed systems is introduced for the parallel implementation to achieve the speedup without specific software and hardware requirement.

关键词： image analysis

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Adapted wavelet analysis on moderate parallel distributed memory MIMD architectures 2nd

Adapted wavelet analysis on moderate parallel distributed me...

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2nd International Workshop on parallel Algorithms for Irregularly Structured Problems, IRREGULAR 1995

作者： Uhl, Andreas Research Institute for Softwaretechnology Salzburg University Austria

ISBN: (纸本)3540603212

Among other adaptive wavelet analysis methods, wavelet packet best basis selection has become a popular method in image compression. This paper introduces a subband based parallelization of the decomposition and the best basis selection. This approach overcomes most of the difficulties of a straightforward parallel version of the sequential algorithm. Beside the higher efficiency the algorithm is easier to implement than its classical version. Results are presented that are achieved through an implementation on a workstationcluster using PVM. © Springer-Verlag Berlin Heidelberg 1995.

关键词： Wavelet analysis

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Task allocation in distributed computer systems through an AI planner solver

Task allocation in distributed computer systems through an A...

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Proceedings of the IEEE 1995 National Aerospace and Electronics Conference. Part 2 (of 2)

作者： Hopper, Chahira M. Pan, Yi Wright Lab Wright Patterson Air Force Base United States

Many avionics systems use specialized parallel architectures to speed processing and to increase system reliability. The software used therein is frequently divided into tasks and executed concurrently on multiple processors under strict real-time constraints critical to the mission's successful performance. Scheduling and planning are needed for effectively managing the computational resources on such avionics architectures. Since most real-time scheduling problems are known to be NP-hard, an approximation approach that applies heuristic methods using conventional computer algorithms has been used to solve these scheduling problems. Artificial Intelligence (AI) planners have been used extensively in manufacturing scheduling and operations research. In this paper, we demonstrate the idea of using AI planners to perform scheduling through an example. We derive a solution to scheduling several image tasks on a distributed computer system, using the AI planner PRODIGY. The basic characteristics of AI planners in general and the PRODIGY solver in particular are described, the domain theory and problem specification for our problem through the PRODIGY description language PDL are presented.

关键词： distributed computer systems

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PROGNOSTIC-SIGNIFICANCE OF DNA-PLOIDY IN ORAL SQUAMOUS-CELL CARCINOMAS - A RETROSPECTIVE HOW AND image CYTOMETRIC STUDY WITH COMPARISON OF DNA-PLOIDY IN EXCISIONAL BIOPSY SPECIMENS AND RESECTION SPECIMENS, PRIMARY TUMORS, AND LYMPH-NODE METASTASES

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ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS 1995年第1期79卷 68-76页

作者： BARETTON, G LI, X STOLL, C FISCHERBRANDIES, E SCHMIDT, M LOHRS, U WUHAN UNIV INST PATHOLWUHAN 430072PEOPLES R CHINA UNIV MUNICH DEPT ORAL & MAXILLOFACIAL SURGMUNICHGERMANY UNIV MUNICH INST MED INFORMAT BIOMETRY & EPIDEMIOLMUNICHGERMANY

Deoxyribonucleic acid ploidy was determined in paraffin-embedded tumor tissue from 116 patients with primary oral squamous cell carcinomas (including 5 carcinomas of the lip and 14 of the tongue) by means of flow cytometry. One hundred six cases were suitable for evaluation (91%). Sixty-eight percent of the cases (n = 72) showed a nondiploid nuclear DNA content. Nondiploidy correlated significantly with presence of lymph node metastases (p < 0.02) but not with tumor stage, grading (World Health Organization), or relapse-free and overall survival. Carcinomas of the lip and tongue turned out to be diploid more frequently than other oral squamous cell carcinomas (p = 0.002). In the 21 cases in which a comparison of DNA content of excisional biopsy specimens and subsequent resection specimens was possible a difference in DNA ploidy was found in one case only. The comparison of primary tumors and their lymph node metastases in 30 cases revealed a discrepancy of DNA content in five cases (17%), which was connected with a shift from nondiploidy to diploidy in four out of five cases. Fifty cases studied in parallel by means of image cytometry with Feulgen-stained tissue sections exhibited a concordance of the ploidy status in 87% and a significant correlation of the DNA index values obtained with both methods (p < 0.01). These results demonstrate that DNA ploidy in oral squamous cell carcinomas is distributed rather homogeneously within the tumors and remains rather stable in the lymph node metastases. Despite a significant correlation between nondiploidy and presence of lymph node metastases, ploidy failed to be a statistically significant parameter for prognosis in oral squamous cell carcinomas in our investigation.

关键词： Aneuploidy Carcinoma Squamous Cell Chi-Square Distribution DNA Neoplasm Female Flow Cytometry Humans image processing Computer-Assisted Linear Models Lip Neoplasms Lymphatic Metastasis Male Middle Aged Mouth Neoplasms Neoplasm Staging Prognosis Retrospective Studies Survival Analysis Tongue Neoplasms

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New data-parallel language features for sparse matrix computations

New data-parallel language features for sparse matrix comput...

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International Symposium on parallel processing

作者： M. Ujaldon E.L. Zapata B.M. Chapman H.P. Zima Department of Computer Architecture University of Malaga Malaga Spain Institute for Soft. Technology and Parallel Systems University of Technology Vienna Vienna Austria

High level data parallel languages such as Vienna Fortran and High Performance Fortran (HPF) have been introduced to allow the programming of massively parallel distributed memory machines at a relatively high level of abstraction, based on the single program multiple data (SPMD) paradigm. Their main features include mechanisms for expressing the distribution of data across the processors of a machine. The paper introduces additional language functionality to allow the efficient processing of sparse matrix codes. It introduces methods for the representation and distribution of sparse matrices, which forms a powerful mechanism for storing and manipulating sparse matrices able to be efficiently implemented on massively parallel machines.< >

关键词： Sparse matrices Educational programs Finite element methods image reconstruction Data structures

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A hierarchical image matching scheme based on the dynamic detection of interesting points

A hierarchical image matching scheme based on the dynamic de...

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International Conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： J. You E. Pissaloux H.A. Cohen School of Computer and Information Science University of South Australia SA Australia Institut dElectronique Fondamentale Université Paris XI Orsay France Department of Computer Science and Computer Engineering La Trobe University Bundoora VIC Australia

This paper presents a parallel approach to a hierarchical image matching scheme using the Hausdorff distance for object recognition and localization in aerial images. Unlike the conventional matching methods in which edge pixels are considered as image feature pixels, the distance transform and the blind pointwise comparison procedure is simplified and extended in terms of the Hausdorff distance, and a guided image matching system is developed by the hierarchical detection of interesting points via a dynamic thresholding scheme for the search of the best matching between two image sets. Furthermore, the concept of remote procedure call (RPC) in distributed systems is introduced for the parallel implementation to achieve the speedup without specific software and hardware requirements.

关键词： image matching image edge detection Pixel Object recognition Hardware

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