共查询到20条相似文献,搜索用时 31 毫秒
1.
Wen-Syan Li K.Selçuk Candan Kyoji Hirata Yoshinori Hara 《The VLDB Journal The International Journal on Very Large Data Bases》2001,9(4):312-326
Due to the fuzziness of query specification and media matching, multimedia retrieval is conducted by way of exploration.
It is essential to provide feedback so that users can visualize query reformulation alternatives and database content distribution.
Since media matching is an expensive task, another issue is how to efficiently support exploration so that the system is not
overloaded by perpetual query reformulation. In this paper, we present a uniform framework to represent statistical information
of both semantics and visual metadata for images in the databases. We propose the concept of query verification, which evaluates queries using statistics, and provides users with feedback, including the strictness and reformulation alternatives
of each query condition as well as estimated numbers of matches. With query verification, the system increases the efficiency
of the multimedia database exploration for both users and the system. Such statistical information is also utilized to support
progressive query processing and query relaxation.
Received: 9 June 1998/ Accepted: 21 July 2000 Published online: 4 May 2001 相似文献
2.
The GMAP: a versatile tool for physical data independence 总被引:1,自引:0,他引:1
Odysseas G. Tsatalos Marvin H. Solomon Yannis E. Ioannidis 《The VLDB Journal The International Journal on Very Large Data Bases》1996,5(2):101-118
Physical data independence is touted as a central feature of modern
database systems. It allows users to frame queries in terms of the logical
structure of the data, letting a query processor automatically translate
them into optimal plans that access physical storage structures. Both
relational and object-oriented systems, however, force users to frame their
queries in terms of a logical schema that is directly tied to physical
structures. We present an approach that eliminates this dependence. All
storage structures are defined in a declarative language based on
relational algebra as functions of a logical schema. We present an
algorithm, integrated with a conventional query optimizer, that translates
queries over this logical schema into plans that access the storage
structures. We also show how to compile update requests into plans that
update all relevant storage structures consistently and optimally.
Finally, we report on experiments with a prototype implementation of our
approach that demonstrate how it allows storage structures to be tuned to
the expected or observed workload to achieve significantly better
performance than is possible with conventional techniques.
Edited by
Matthias Jarke, Jorge Bocca, Carlo Zaniolo. Received
September 15, 1994 / Accepted September 1, 1995 相似文献
3.
The next generation of interactive multimedia documents can contain both static media, e.g., text, graph, image, and continuous
media, e.g., audio and video, and can provide user interactions in distributed environments. However, the temporal information
of multimedia documents cannot be described using traditional document structures, e.g., Open Document Architecture (ODA)
and Standard Generalized Mark-up Language (SGML); the continuous transmission of media units also raises some new synchronization
problems, which have not been met before, for processing user interactions. Thus, developing a distributed interactive multimedia
document system should resolve the issues of document model, presentation control architecture, and control scheme. In this
paper, we (i) propose a new multimedia document model that contains the logical structure, the layout structure, and the temporal
structure to formally describe multimedia documents, and (ii) point out main interaction-based synchronization problems, and
propose a control architecture and a token-based control scheme to solve these interaction-based synchronization problems.
Based on the proposed document model, control architecture, and control scheme, a distributed interactive multimedia document
development mechanism, which is called MING-I, is developed on SUN workstations. 相似文献
4.
5.
We describe a system which supports dynamic user interaction with multimedia information using content-based hypermedia navigation
techniques, specialising in a technique for navigation of musical content. The model combines the principles of open hypermedia, whereby hypermedia link information is maintained by a link service, with content-based retrieval techniques in which a database is queried based on a feature of the multimedia content; our approach could be described as
‘content-based retrieval of hypermedia links’. The experimental system focuses on temporal media and consists of a set of
component-based navigational hypermedia tools. We propose the use of melodic pitch contours in this context and we present
techniques for storing and querying contours, together with experimental results. Techniques for integrating the contour database
with open hypermedia systems are also discussed. 相似文献
6.
Aya Soffer Hanan Samet 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(4):253-274
Symbolic images are composed of a finite set of symbols that have a semantic meaning. Examples of symbolic images include
maps (where the semantic meaning of the symbols is given in the legend), engineering drawings, and floor plans. Two approaches
for supporting queries on symbolic-image databases that are based on image content are studied. The classification approach
preprocesses all symbolic images and attaches a semantic classification and an associated certainty factor to each object
that it finds in the image. The abstraction approach describes each object in the symbolic image by using a vector consisting
of the values of some of its features (e.g., shape, genus, etc.). The approaches differ in the way in which responses to queries
are computed. In the classification approach, images are retrieved on the basis of whether or not they contain objects that
have the same classification as the objects in the query. On the other hand, in the abstraction approach, retrieval is on
the basis of similarity of feature vector values of these objects. Methods of integrating these two approaches into a relational
multimedia database management system so that symbolic images can be stored and retrieved based on their content are described.
Schema definitions and indices that support query specifications involving spatial as well as contextual constraints are presented.
Spatial constraints may be based on both locational information (e.g., distance) and relational information (e.g., north of).
Different strategies for image retrieval for a number of typical queries using these approaches are described. Estimated costs
are derived for these strategies. Results are reported of a comparative study of the two approaches in terms of image insertion
time, storage space, retrieval accuracy, and retrieval time.
Received June 12, 1998 / Accepted October 13, 1998 相似文献
7.
In this paper, we investigate a playout scheduling framework for supporting the continuous and synchronized presentations
of multimedia streams in a distributed multimedia presentation system. We assume a situation in which the server and network
transmissions provide sufficient support for the delivery of media objects. In this context, major issues regarding the enforcement
of the smooth presentation of multimedia streams at client sites must be addressed to deal with rate variance of stream presentations
and delay variance of networks. We develop various playout-scheduling algorithms that are adaptable to quality-of-service
parameters. The proposed algorithms permit the local adjustment of unsynchronized presentations by gradually accelerating
or retarding presentation components, rather than abruptly skipping or pausing the presentation materials. A comprehensive
experimental analysis of the proposed algorithms demonstrates that our algorithms can effectively avoid playout gaps (or hiccups)
in the presentations. This scheduling framework can be readily used to support customized multimedia presentations. 相似文献
8.
This paper describes an approach to the problem of articulating multimedia information based on parsing and syntax-directed
translation that uses Relational Grammars. This translation is followed by a constraint-solving mechanism to create the final
layout. Grammatical rules provide the mechanism for mapping from a representation of the content and context of a presentation
to forms that specify the media objects to be realized. These realization forms include sets of spatial and temporal constraints
between elements of the presentation. Individual grammars encapsulate the “look and feel” of a presentation and can be used
as generators of such a style. By making the grammars sensitive to the requirements of the output medium, parsing can introduce
flexibility into the information realization process. 相似文献
9.
Bing Wang 《International Journal on Digital Libraries》1999,2(2-3):91-110
A digital library (DL) consists of a database which contains library information and a user interface which provides a visual
window for users to search relevant information stored in the database. Thus, an abstract structure of a digital library can
be defined as a combination of a special purpose database and a user-friendly interface. This paper addresses one of the fundamental aspects of such
a combination. This is the formal data structure for linking an object oriented database with hypermedia to support digital
libraries. It is important to establish a formal structure for a digital library in order to efficiently maintain different
types of library information. This article discusses how to build an object oriented hybrid system to support digital libraries.
In particular, we focus on the discussion of a general purpose data model for digital libraries and the design of the corresponding
hypermedia interface. The significant features of this research are, first, a formalized data model to define a digital library
system structure; second, a practical approach to manage the global schema of a library system; and finally, a design strategy
to integrate hypermedia with databases to support a wide range of application areas.
Received: 15 December 1997 / Revised: June 1999 相似文献
10.
Over the last few years, there has been a tremendous increase in the number of interactive multimedia presentations prepared
by different individuals and organizations. In this paper, we present an algebra for creating and querying interactive multimedia
presentation databases. This algebra operates on trees whose branches reflect different possible playouts of a set of presentations.
The algebra not only extends all the classical relational operators to such databases, but also introduces a variety of novel
operators for combining multiple presentations. As our algebra supports merging parts or all of existing presentations, this
algebra can also be used as an authoring tool for creating multimedia presentations. We prove a host of equivalence results
for queries in this algebra, which may be used to build query optimizers for interactive presentation databases. 相似文献
11.
Serge Abiteboul Sophie Cluet Tova Milo 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(2):96-114
Structured data stored in files can benefit from standard database technology. In particular, we show here how such data
can be queried and updated using declarative database languages. We introduce the notion of structuring schema, which consists of a grammar annotated with database programs. Based on a structuring schema, a file can be viewed as a database
structure, queried and updated as such. For queries, we show that almost standard database optimization techniques can be used to answer queries without having to construct
the entire database. For updates, we study in depth the propagation to the file of an update specified on the database view of this file. The problem is not
feasible in general and we present a number of negative results. The positive results consist of techniques that allow to
propagate updates efficiently under some reasonable locality conditions on the structuring schemas.
Received November 1, 1995 / Accepted June 20, 1997 相似文献
12.
Multimedia databases 总被引:2,自引:0,他引:2
A.Desai Narasimhalu 《Multimedia Systems》1996,4(5):226-249
The rapidly growing interest in building multimedia tools and applications has created a need for the development of multimedia
database management systems (MMDBMSs) as a tool for efficient organization, storage and retrieval of multimedia objects. We
begin with a word about traditional database management systems (DBMSs). Then we present an overview of the MMDBMS research
issues, challenges, methods, models, and architectures. We review the state of the art and research contributions from related
disciplines. Finally, we consider possibilities and probabilities for MMDBMS research in the future. 相似文献
13.
When multimedia information is transported over a packet-switched network, the quality of presentation can be degraded due
to network delay variation or jitter. This paper presents a dejittering scheme that can be used in the transport of MPEG-4
and MPEG-2 video to absorb any introduced network jitter, thus preserving the presentation quality of transported media streams.
The dejittering scheme is based on the statistical approximation of delay variation in the arrival times of video packets
carrying encoded clock reference values and a filtering and re-stamping mechanism. In addition, a brief overview of the MPEG-4
system is presented. 相似文献
14.
The most common way of designing databases is by means of a conceptual model, such as E/R, without taking into account other
views of the system. New object-oriented design languages, such as UML (Unified Modelling Language), allow the whole system,
including the database schema, to be modelled in a uniform way. Moreover, as UML is an extendable language, it allows for
any necessary introduction of new stereotypes for specific applications. Proposals exist to extend UML with stereotypes for
database design but, unfortunately, they are focused on relational databases. However, new applications require complex objects
to be represented in complex relationships, object-relational databases being more appropriate for these requirements. The
framework of this paper is an Object-Relational Database Design Methodology, which defines new UML stereotypes for Object-Relational
Database Design and proposes some guidelines to translate a UML conceptual schema into an object-relational schema. The guidelines
are based on the SQL:1999 object-relational model and on Oracle8i as a product example.
Initial submission: 22 January 2002 / Revised submission: 10 June 2002
Published online: 7 January 2003
This paper is a revised and extended version of Extending UML for Object-Relational Database Design, presented in the UML’2001
conference [17]. 相似文献
15.
Lawrence D. Bergman Jerre Shoudt Vittorio Castelli Chung-Sheng Li Loey Knapp 《International Journal on Digital Libraries》1999,2(2-3):178-189
In this paper, we describe a new interface for querying multimedia digital libraries and an interface building framework.
The interface employs a drag-and-drop style of interaction and combines a structured natural-language style query specification
with reusable multimedia objects. We call this interface DanDMM, short for “drag-and-drop multimedia”. DanDMM interfaces capture
the syntax of the underlying query language, and dynamically reconfigure to reflect the contents of the data repository.
A distinguishing feature of DanDMM is its ability to synthesize integrated interfaces that incorporate both example-based
specification using multimedia objects, and traditional techniques including keyword, attribute, and free text-based search.
We describe the DanDMM-builder, a framework for synthesizing DanDMM interfaces, and give several examples of interfaces that
have been constructed using DanDMM-builder, including a remote-sensing library application and a video digital library.
Received: 15 December 1997 / Revised: June 1999 相似文献
16.
Answering queries using views: A survey 总被引:25,自引:0,他引:25
Alon Y. Halevy 《The VLDB Journal The International Journal on Very Large Data Bases》2001,10(4):270-294
The problem of answering queries using views is to find efficient methods of answering a query using a set of previously
defined materialized views over the database, rather than accessing the database relations. The problem has recently received
significant attention because of its relevance to a wide variety of data management problems. In query optimization, finding
a rewriting of a query using a set of materialized views can yield a more efficient query execution plan. To support the separation
of the logical and physical views of data, a storage schema can be described using views over the logical schema. As a result,
finding a query execution plan that accesses the storage amounts to solving the problem of answering queries using views.
Finally, the problem arises in data integration systems, where data sources can be described as precomputed views over a mediated
schema. This article surveys the state of the art on the problem of answering queries using views, and synthesizes the disparate
works into a coherent framework. We describe the different applications of the problem, the algorithms proposed to solve it
and the relevant theoretical results.
Received: 1 August 1999 / Accepted: 23 March 2001 Published online: 6 September 2001 相似文献
17.
A survey of approaches to automatic schema matching 总被引:76,自引:1,他引:75
Erhard Rahm Philip A. Bernstein 《The VLDB Journal The International Journal on Very Large Data Bases》2001,10(4):334-350
Schema matching is a basic problem in many database application domains, such as data integration, E-business, data warehousing,
and semantic query processing. In current implementations, schema matching is typically performed manually, which has significant
limitations. On the other hand, previous research papers have proposed many techniques to achieve a partial automation of
the match operation for specific application domains. We present a taxonomy that covers many of these existing approaches,
and we describe the approaches in some detail. In particular, we distinguish between schema-level and instance-level, element-level
and structure-level, and language-based and constraint-based matchers. Based on our classification we review some previous
match implementations thereby indicating which part of the solution space they cover. We intend our taxonomy and review of
past work to be useful when comparing different approaches to schema matching, when developing a new match algorithm, and
when implementing a schema matching component.
Received: 5 February 2001 / Accepted: 6 September 2001 Published online: 21 November 2001 相似文献
18.
19.
Adaptive multimedia synchronization in a teleconference system 总被引:3,自引:0,他引:3
In this paper, we present an adaptive buffering scheme for implementing intra-stream and inter-stream synchronization in
real-time multimedia applications. The essence of the proposed scheme is to dynamically enforce equalized delays to incoming
media streams, in order to piece-wise smooth the network delay variations and to synchronize the streams at the sink. An adaptive
control mechanism based on an event-counting algorithm is employed to calibrate the PlayOut Clocks (POCs), which manages the
presentations of multimedia data. The algorithm does not rely on globally synchronized clock and makes minimal assumption
on underlying network delay distribution. Also, the user defined quality of service (QoS) specifications can be directly incorporated
into the design parameters of the synchronization algorithm. The proposed synchronization scheme has been experimentally implemented
in a teleconference system which consists of separately controllable audio, video, and data channels. The modular structure
of the synchronization control provides the flexibility to maintain an arbitrary synchronization group in conjunction with
a distributed conference management scheme. This paper also shows the experimental results of the test implementation and
the suitability of the proposed scheme with respect to the multimedia traffic across an FDDI/Ethernet network. 相似文献
20.
Control of perceived quality of service in multimedia retrieval services: prediction-based mechanism vs. compensation buffers 总被引:3,自引:0,他引:3
Aurelio La Corte Alfio Lombardo Sergio Palazzo Giovanni Schembra 《Multimedia Systems》1998,6(2):102-112
In multimedia systems end-to-end delay jitter has a great impact on the continuity of information playback. Therefore, it
is necessary to introduce appropriate mechanisms to compensate for delay variations, so that the intramedia and intermedia
temporal relationships can be preserved. In this paper, two methods for compensation of the network delay jitter in a distributed
multimedia retrieval service are compared: the first is based on prediction of the network delay jitter suffered by each information
unit and retrieval time modification at the source site; the second is based on a compensation buffer at the destination site.
Comparison is made by assuming a master/slave relationship between the monomedia streams composing the multimedia data flow. 相似文献