5388492
On-the-Fly rendering of losslessly compressed irregular volume data
Very large irregular-grid data sets are represented as tetrahedral mesh and may incur significant disk I/O access overhead in the rendering process. An effective way to alleviate the disk I/O overhead associated with rendering large tetrahedral mesh is to reduce the I/O bandwidth requirement through compression. Existing tetrahedral mesh compression algorithms focus only on compression efficiency and cannot be readily integrated into the mesh rendering process, and thus demand that a compressed tetrahedral mesh be decompressed before it can be rendered into a 2D image. This paper presents an integrated tetrahedral mesh compression and rendering algorithm calledGatun, which allows compressed tetrahedral meshes to be rendered incrementally as they are being decompressed, thus forming an efficient irregular grid rendering pipeline. Both compression and rendering algorithms in Gatun exploit the same local connectivity information among adjacent tetrahedra, and thus can be tightly integrated into a unified implementation framework. Our tetrahedral compression algorithm is specifically designed to facilitate the integration with irregular grid renderer without any compromise in compression efficiency. A unique performance advantage of Gatunis its ability to reduce the run-time memory footprint requirement by releasing memory allocated to tetrahedra as early as possible. As a result, Gatunis able to decrease rendering time by a factor of 2 for very large tetrahedral mesh whose size exceeds the amount of physical memory. At the same time, the smaller working set and better access locality of Gatunimprove the rendering performance by up to 30%, even when the input tetrahedral mesh is entirely memory-resident. CR Categories: I.3.3 [Computer Graphics]: Picture/Image Generation—Display Algorithms; E.4 [Coding and Information Theory]: Data Compaction and Compression.
35542914
A Decoupled Architecture for Application-Specific File Prefetching
6437408
Application-specific file prefetching for multimedia programs
This paper describes the design, implementation, and evaluation of an automatic application-specific file prefetching mechanism that is designed to improve the I/O performance of multimedia programs with complicated access patterns. The key idea of the proposed approach is to convert an application into two threads: a computation thread, which is the original program containing both computation and disk I/O, and a prefetch thread, which contains all the instructions in the original program that are related to disk accesses. At run time, the prefetch thread is scheduled to run far ahead of the computation thread, so that disk blocks can be prefetched and put in the file system buffer cache before the computation thread needs them. A source-to-source translator is developed to automatically generate the prefetch and computation thread from a given application program without any user intervention. We have successfully implemented a prototype of this automatic application-specific file prefetching mechanism under Linux. The prototype is shown to provide as much as 54% overall performance improvement for real-world multimedia applications.
5738405
Zodiac: A history-based interactive video authoring system
Abstract. Easy-to-use audio/video authoring tools play a crucial role in moving multimedia software from research curiosity to mainstream applications. However, research in multimedia authoring systems has rarely been documented in the literature. This paper describes the design and implementation of an interactive video authoring system called Zodiac, which employs an innovative edit history abstraction to support several unique editing features not found in existing commercial and research video editing systems. Zodiac provides users a conceptually clean and semantically powerful branching history model of edit operations to organize the authoring process, and to navigate among versions of authored documents. In addition, by analyzing the edit history, Zodiac is able to reliably detect a composed video stream's shot and scene boundaries, which facilitates interactive video browsing. Zodiac also features a video object annotation capability that allows users to associate annotations to moving objects in a video sequence. The annotations themselves could be text, image, audio, or video. Zodiac is built on top of MMFS, a file system specifically designed for interactive multimedia development environments, and implements an internal buffer manager that supports transparent lossless compression/decompression. Shot/scene detection, video object annotation, and buffer management all exploit the edit history information for performance optimization.
6822991
An Integrated Pipeline of Decompression, Simplification and Rendering for Irregular Volume Data
Very large irregular-grid volume data sets are typically represented as tetrahedral mesh and require substantial disk I/O and rendering computation. One effective way to reduce this demanding resource requirement is compression. Previous research showed how rendering and decompression of a losslessly compressed irregular-grid data set can be integrated into a one-pass computation. This work advances the state of the art one step further by showing that a losslessly compressed irregular volume data set can be simplified while it is being decompressed and that simplification, decompression, and rendering can again be integrated into a pipeline that requires only a single pass through the data sets. Since simplification is a form of lossy compression, the on-the-fly volume simplification algorithm provides a powerful mechanism to dynamically create versions of a tetrahedral mesh at multiple resolution levels directly from its losslessly compressed representation, which also corresponds to the finest resolution level. In particular, an irregular-grid volume renderer can exploit this multi-resolution representation to maintain interactivity on a given hardware/software platform by automatically adjusting the amount of rendering computation that could be afforded, or performing so called time-critical rendering. The proposed tetrahedral mesh simplification algorithm and its integration with volume decompression and rendering has been successfully implemented in the Gatun system. Performance measurements on the Gatun prototype show that simplification only adds less than 5% of performance overhead on an average and with multi-resolution pre-simplification the end-to-end rendering delay indeed decreases in an approximately linear fashion with respect to the simplification ratio.
1742512
On Construction of a Large File System Using PVFS for Grid
Grid is the largest advance of network after Internet since the Grid System provides a specialty that can be used popularly and effectively. However, it is a challenge to the consistency and community of use on the data storages space of a Grid System. Therefore, the problem of application for the Computational Grid and Data Grid is more important. It can set up a usability, expandability, high operation capability, and large memory space in Grid with the Cluster system and parallel technique in order to solve the problem. In this paper, we provided a Grid with high operation capability and higher memories to solve the problem. As to the Grid setting, we take use of the Cluster computing to increase the operation effect for computing, and a PVFS2 with more storages effect for data. It can supply a quite correct platform for Grid user whether for large data access or huge operation.
16831415
Automatic construction of English/Chinese parallel corpora
As the demand for global information increases significantly, multilingual corpora has become a valuable linguistic resource for applications to cross-lingual information retrieval and natural language processing. In order to cross the boundaries that exist between different languages, dictionaries are the most typical tools. However, the general-purpose dictionary is less sensitive in both genre and domain. It is also impractical to manually construct tailored bilingual dictionaries or sophisticated multilingual thesauri for large applications. Corpus-based approaches, which do not have the limitation of dictionaries, provide a statistical translation model with which to cross the language boundary. There are many domain-specific parallel or comparable corpora that are employed in machine translation and cross-lingual information retrieval. Most of these are corpora between Indo-European languages, such as English/French and English/Spanish. The Asian/Indo-European corpus, especially English/Chinese corpus, is relatively sparse. The objective of the present research is to construct English/ Chinese parallel corpus automatically from the World Wide Web. In this paper, an alignment method is presented which is based on dynamic programming to identify the one-to-one Chinese and English title pairs. The method includes alignment at title level, word level and character level. The longest common subsequence (LCS) is applied to find the most reliable Chinese translation of an English word. As one word for a language may translate into two or more words repetitively in another language, the edit operation, deletion, is used to resolve redundancy. A score function is then proposed to determine the optimal title pairs. Experiments have been conducted to investigate the performance of the proposed method using the daily press release articles by the Hong Kong SAR government as the test bed. The precision of the result is 0.998 while the recall is 0.806. The release articles and speech articles, published by Hongkong & Shanghai Banking Corporation Limited, are also used to test our method, the precision is 1.00, and the recall is 0.948.
8656490
Large Primes in Stream Cipher Cryptography
The present research is motivated by the observation that if the period T of a certain binary sequence is a prime, then its linear complexity will be bounded from below by the order of 2 modulo T, i.e., LC⩾OrdT(2). A class of generators with state periods T(q, n)=q·2n−1 are constructed for q=3, 5, 7, 9 and arbitrary n on the basis of a pair of m-sequence generators with the same number of stages, each controlling the clock of the other (bilateral stop-and-go clock control). A new test is derived to find the primes among the numbers T(q, n) with the cases 3 | q and 3 | q treated in a unified manner. The orders of 2 modulo some of the primes T(q, n) are given and some additional cryptographic and implementational remarks are made.
8537388
Implementation of visual MPI parallel program performance analysis tool for cluster environments
In this paper, we present visual tool for performance measurement and analysis of MPI parallel programs in cluster environments. Most of tools available today for cluster systems show solely system performance data (e.g., CPU load, memory usage, network bandwidth, machine-room temperature, server average load, among others), being more suitable for system administrators who maintain such system. The visual tool is designed to show performance data of all computer nodes involved in the execution of MPI parallel program, such as CPU load level and memory usage. Additionally, this tool is able to display comparative performance data charts of multiple executions of the application (instrumented with MPI interface) under development.
2271054
An information delivery system with automatic summarization for mobile commerce
Wireless access with handheld devices is a promising addition to the WWW and traditional electronic business. Handheld devices provide convenience and portable access to the huge information space on the Internet without requiring users to be stationary with network connection. Many customer-centered m-services applications have been developed. The mobile computing, however, should be extended to decision support in an organization. There is a desire of accessing most update and accurate information on handheld devices for fast decision making in an organization. Unfortunately, loading and visualizing large documents on handheld devices are impossible due to their shortcomings. In this paper, we introduce the fractal summarization model for document summarization on handheld devices. Fractal summarization is developed based on the fractal theory. It generates a brief skeleton of summary at the first stage, and the details of the summary on different levels of the document are generated on demands of users. Such interactive summarization reduces the computation load in comparing with the generation of the entire summary in one batch by the traditional automatic summarization, which is ideal for wireless access. The three-tier architecture with the middle-tier conducting the major computation is also discussed. Visualization of summary on handheld devices is also investigated. The automatic summarization, the three-tier architecture, and the information visualization are potential solutions to the existing problems in information delivery to handheld devices for mobile commerce.