USING A STANDARDS-BASED APPROACH FOR A

MULTIMEDIA KNOWLEDGE-BASE

Maria Ilaria Lunesu, Filippo Eros Pani and Giulio Concas

Department of Electrics and Electronics Engineering, University of Cagliari, Piazza d'Armi, Cagliari, Italy

Keywords: Multimedia content, Ontology, Mapping, Knowledge-base.

Abstract: In recent years, we witnessed the diffusion and rise in popularity of software platforms for User Generated

Content management, especially multimedia objects. These platforms handle a big quantity of unclassified

information. UGC sites (i.e. YouTube and Flickr) do not force the users to perform classification operations

and metadata definitions, leaving space to a logic of free-tags (Folksonomies). In the context of an industrial

project financed by the Autonomous Region of Sardinia, the idea of producing a Geolocalized Guide based

on a Knowledge-base came forth. Such Guide would be able to share georeferenced content with their users,

originated from UGC sources as well as from users themselves. For this purpose, we defined an ontology

that can represent the semantics of multimedia content, especially its metadata, which in turn can be given

an unambiguous meaning. The innovation in this work is represented by the use of the Adobe XMP,

DUBLIN CORE, EXIF, IPTC standards as a starting point. In order to unify metadata coming from

different sources we defined all laws of mapping toward a structure defined by sources like YouTube and

Flickr.

1 INTRODUCTION

It has been observed how, in recent years, many

software platforms managing big quantities of

multimedia content have risen in popularity within

the Web-2.0. UGCs in particular, the most famous of

which are Youtube, Flickr, Del.icio.us, Zooomr,

Picasa, own their great success to a spread of digital

technology accessible by a mass, paralleled by the

quantity and quality of the services offered. The

prominent features of such platforms are their ease

of use, the possibility for users to create and manage

their own spaces (personal channels or pages),

carrying and sharing any kind of multimedia content

from various sources, the implementation of

efficient content research and localization methods,

the definition of access and usage types for them,

and storage of information about legal restrictions

and rights management. When the first problems

about interoperability of applications and

management of shared means arose inside those

platforms, moving on to a more effective

representation of knowledge became a necessity,

along with the evolution of the Web in its semantic

form named Web 3.0.

In particular, we wanted data and resources to be

conceived and represented not through a description

of their structure (syntax), but by a definition of their

meaning (semantics), and for this to be shared within

the community using those same data.

In the context of an industrial project financed by

the Autonomous Region of Sardinia, we fostered the

idea of developing a Guide based on a Knowledge-

base which could manage content from UGC

sources like Flickr and YouTube available for their

users, in addition to contents the users add into the

system, with georeferenced information.

The purpose of this study is to give an

unambiguous meaning to those information so that

they can be managed with a single Knowledge-base.

In order to achieve this goal we chose to define

an ontology that is able to represent the semantics of

these multimedia contents and their metadata, with

the most used standards to define metadata in this

domain (Adobe XMP, DUBLIN CORE, EXIF,

IPTC) as starting points as proven by Gruber (2008).

The innovation of this work is that we chose to

base our approach on the use of the Adobe XMP

standard as a description of the domain of

multimedia metadata, which gives the opportunity to

exhaustively represent multimedia content and its

metadata as well as the other mentioned standards

(DC, EXIF e IPTC).

Lunesu M., Pani F. and Concas G..

USING A STANDARDS-BASED APPROACH FOR A MULTIMEDIA KNOWLEDGE-BASE.

DOI: 10.5220/0003663300870095

In Proceedings of the International Conference on Knowledge Management and Information Sharing (KMIS-2011), pages 87-95

ISBN: 978-989-8425-81-2

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

In the second section of this paper we recall

some aspects about the state of the art concerning

ontologies and standards used to represent metadata

related to multimedia contents.

In the third, we present our methodology and

address the analysis of the metadata typical of our

two UGC sources, Youtube and Flickr, and

Folksonomies. We also describe the testing done,

with a description of the different phases of ontology

building and mapping technology we developed.

The fourth section includes the conclusion and

reasonings about the future evolution of the

proposed project.

2 STATE OF THE ART

2.1 Standard Description

Ontologies are an increasingly popular tool thanks to

the advantages they offer when sharing information.

For a few years they have played a leading role in

the representation and utilization of knowledge

processes. In the past, the study of ontology focused

mainly on its philosophical context, but recently it

has assumed an important role in a different research

and industrial section. Ontologies are in fact able to

isolate, retrieve, organize and integrate information

according to their core feature, their semantic

context. Multimedia Ontologies have many

application fields, including Content Visualization,

Knowledge Sharing and Learning as proven by

Jaimes and Smith (2003) and by Kameas and

Seremeti (2007). Their structure and semantics are

accurately modelled to be broadly consistent with

existing multimedia description standards like

MPEG-7 as shown by Martínez, Koenen and Pereira

(2002).

There are two different approach to this kind of

ontologies. Media-Speciﬁc Ontologies (that use

different kinds of multimedia taxonomies and

describe different kinds of object properties) and

Content-Speciﬁc Ontologies (that describe the

content of resources, e.g. the scenarios or the

participant) as proven in Alesso and Smith (2008).

The construction of multimedia ontologies is

rather complex, it is an iterative process whereby a

phase for the selection of concepts to include in the

ontology, a phase to create properties and relations

linking them together, and a phase for maintenance

of the ontology. We could mention many attemps to

create a multimedia content ontology. In (Jaimes and

Smith, 2003) and (Benitez and Chang, 2003) new

methods for extracting semantic knowledge from

data are presented.

In (Strintzis et al., 2004), we used a Visual

Descriptors Ontology and a Multimedia Structure

Ontology with a domain ontology that aims to

support the note of content. There are other works as

shown in (Bertini et al., 2005), (Bertini et al., 2006),

(Petridis et al., 2006) that are not applicable in this

contest.

As regards our work (that we will describe in the

next sections) we referred to standards as domain

reference, which fit with the management and

categorization of different types of content and

georeferenced data. These standards will be

described below.

2.1.1 XMP Standard

The Adobe Extensible Metadata Platform (XMP) is

a standard, created by Adobe Systems Inc., for

processing and storing standardized and proprietary

information relating to the contents of a file.

XMP standardizes the definition, creation, and

processing of extensible metadata. Serialized XMP

can be embedded into a significant number of

popular file formats, without breaking their

readability by non-XMP-aware applications.

Embedding metadata avoids many problems that

occur when metadata is stored separately. XMP is

used in PDF, photography and photo editing

applications.

XMP encapsulates metadata inside the file, using

RDF (Resource Description Framework), a basic

tool proposed by W3C for encoding, exchange and

reuse of the structured metadata as proven by W3C.

The standard allows, in addition to other things,

interoperability between the different applications

that interact on the web. The reason for its use is that

it is a common standard for a wide range of

applications, which allows us to work efficiently and

effectively on metadata. These properties have

encouraged the rapid spread at many companies

operating in the digital media, which integrate their

applications with this technology. XMP has been

designed and thought also to define, create and

elaborate user-defined metadata which are compliant

with the standards.

2.1.2 Dublin Core (DC) Standard

Dublin Core is a standard for metadata that consists

of a core of essential elements for the description of

any digital material accessible via a computer

network as proven by (Becker et al., 1977). They

proposed a set of 15 basic elements extended also to

KMIS 2011 - International Conference on Knowledge Management and Information Sharing

sub-elements or qualifiers: each element is defined

using a set of 10 properties obtained by a standard

ISO 11179. The main features of DC are follows:

1) ease of use the standard is aimed at specialized

cataloguers which are not experts in cataloguing, as

users;

2) semantic interoperability, which gives rise to a

complex and precise data system the meaning of

which has been agreed in advance, along with a

value that allows the DC to be a standard for quality

research in Internet; flexibility, as it allows you to

integrate and develop the data structure with

different semantic meanings and a congenial

application environment.

2.1.3 EXIF Standard

The EXIF standard was created by Japan Electronics

and Information Technology Industries Association

for metadata of digital images. This is a structure

supported by the main producers of cameras and is

studied to give users the opportunity to supply

photos with interchangeable information between

imaging devices to improve processing and printing.

The rapid spread of digital cameras and related

tools increased the need to exchange images directly

from cameras or other instruments, or to display an

image taken with a camera through either another, or

a different device altogether.

EXIF offers a set of specific tags in itself,

concerning shooting parameters and settings of the

device at the time of capture (JEITA, 2002).

2.1.4 International Press

Telecommunication Council (IPTC)

Standard

IPTC is a standard that offers an advantage to

relations and exchanges among entities devoted to

information creation and distribution. It is sponsored

and defined by a consortium based in London that

encompasses the leading news companies in the

information world, such as Reuters, Associated

Press and France Press. IPTC does not hold, among

its metadata, fields related to technical information

on a digital object; in fact, the metadata of the digital

object itself, present in other standards like EXIF,

are not defined. The focus of IPTC in defining the

standard is on analyzing what surrounds the many

situations of telecommunications, and on studying

their production process. Therefore, a range of

metadata were defined, which are useful to define

and certificate all digital object production activities

for print or editing (IPTC, 2008).

2.2 Support Tools

The work needed a preliminary and careful study of

ontologies and the most suitable tools for ontology

editing. We chose Protégé (Stanford Center for

Biomedical Informatics Research), a knowledge-

base and open source framework developed at

Stanford University.

Protégé is able to implement a rich set of

structures and knowledge-modelling actions to

support creation, viewing and manipulation of

ontologies in various representation formats.

Below is an overview of the software platforms

analyzed and taken as an example for mapping

strategy development.

2.3 YouTube

YouTube is an Internet site for video sharing.

Founded in February 2005 by Chad Hurley, Steve

Chen and Jawed Karim (all former PayPal

employees), it is now property of Google Inc. It is

the third most visited site in the world next to

Google itself and Facebook.

YouTube uses the Adobe Flash technology to

play its contents, and it aims to host only videos

created directly by the uploader. This platform

makes an intensive usage of feeds containing

objects, such as web link to content sources. The

interaction between YouTube and clients is managed

through a protocol named YouTube Data API

Protocol, a program communication interface

application.

The data existing in the API are shown by the

protocol as views or projections, with the ability to

modify the form a feed is to be presented with.

However, content is preserved as it is. In this way,

two different projections from the same feed will

identify the same objects, but using different XML

tag sets in (Bray et al., 1998) and (W3C, 2007).

2.4 Flickr

Flickr, developed by Ludicorp (a Canadian company

in Vancouver founded in 2002), is a multilingual

web site that allows users to share personal pictures

with whoever has access to the Internet, in a Web

2.0 environment. The site, owned by the Yahoo!

group, has an ever growing library and was one of

the first to implement tag clouds, visual

representations of user-generated tags. Tag clouds

allow access to images tagged with the most popular

keywords. Thanks to this support for tags, Flickr

was mentioned as the first example of actual

USING A STANDARDS-BASED APPROACH FOR A MULTIMEDIA KNOWLEDGE-BASE

folksonomy use, although Thomas Vander Wal

suggested Flickr is not the best example (Vander

Wal, 2007).

Flickr supports standard metadata sets (it shows

the entire Exif metadata set for every picture),

keywords for searches and a group of tags belonging

to folksonomies.

As far as the georeferencing is concerned, Flickr

allows users to organize their pictures in 'sets', that is

groups of images sharing the same gallery. Sets are

more flexible than the traditional folder organization

method for files: a picture can belong to one or more

sets, or to none. Those sets represent a form of

category metadata, instead of a physical hierarchy.

The pictures in a set can be geotagged, and every

set of geotagged pictures can be put in relation with

a map using ImapFlickr2. Such a map can then be

embedded in Web sites.

2.5 Folksonomies

Folksonomies are a set of terms used by a group of

users to tag its own contents (Vander Wal, 2007).

An important aspect of folksonomies is that they

are made up of terms belonging to an open

namespace, i.e. there is neither a hierarchy nor a

parent-child relation among the terms. The only

standard they conform to is the one the tags are

formalized with: namespace:property=value (with

no rules on the other three parts that complete the

assertion) (Vander Wal, 2005); (Mathes, 2004).

3 ONTOLOGY BUILDING

Considering the current literature, the approach we

followed in building a multimedia content ontology

assumes the XMP, Dublin Core, EXIF and IPCT

standards, as well as the related XML schemas and

the integration with the semantics through RDF, as a

basic Knowledge-base for the starting domain as

proven by Lassila and Swick (1999) and by Brickley

and Guha (2000). Thus a complete modelling of the

domain of multimedia content properties, coming

from different sources, is guaranteed together with

an uniform representation of the variety of

associated metadata.

The reason for choosing this approach lies in the

fact that such standards allow for cataloguing

different aspects of multimedia content and natively

possess the specification tools for georeferenced

information. The ontology was then modelled on

those standards, selecting the relevant elements.

Once the basic ontology was decided, an analysis

on cataloguing and classification of metadata in

contents from the main software platforms of the

Net followed. Thanks to this we could acknowledge

alternative standards and proprietary formats used.

Given the great number of available platforms on

the Net and since analyzing all of them would have

been too onerous for us, it was necessary to narrow

the scope and choose which ones should be

considered.

After a study of all the features related to

metadata on the chosen UGC sites, we worked on a

mapping mechanism that allows such data and

associated metadata to be represented within the

ontology.

3.1 Ontology Modelling on Standards

The first step in creating an ontology implies

acquiring knowledge about the domain to be

modelled (Noy and McGuiness, 2001). In order to

do this, we started from the assumption that the

reference domain is the one that includes every kind

of multimedia content, both currently available in

the web or through modern digital technologies,

equipped with sets of metadata belonging to the

above mentioned standards.

The purpose of the ontology is to model the

semantics of metadata from various multimedia

contents, providing for georeferencing and mapping

of the different standards related to metadata. Their

representation can thus comply with the

reconciliation standard provided by the MWG and

with Adobe XMP.

The ontology must be able to receive a content

coming from social networks or software platforms

for content management without information loss or

alteration.

The resulting ontology can be used as a

Knowledge-base supporting the Geolocalized Guide.

As per the definition of the ontology, we chose to

categorize the concepts according to the expression

sublanguage named OWL DL (Description Logic),

due to its computational completeness, its

decidability and the fact it guarantees maximum

expressivity (Carroll and De Roo, 2004);

(McGuinness and Van Harmelen, 2004); (Heflin,

2004). The structure of the ontology was created by

modelling the concepts mentioned above as classes

or properties, following a middle-out approach. First

of all we proceeded with the definition of relations

and main entities which were progressively

generalized and specialized.

These structures were integrated with RDF

schemas. In particular, the entire set of metadata

KMIS 2011 - International Conference on Knowledge Management and Information Sharing

required by the EXIF standard, together with the

entire Dublin Core set (complete with its refiniment

terms), was imported. Both schemas allow the

ontology to exploit their metadata, making them

available as particular properties, datatype

properties and object properties at the same time,

probably so as to satisfy every kind of usage needs.

In this specific case they were used solely as

object properties, i.e. to link class instances with

other class instances. The main classes involved in

ontology building are basically four:

1) MultimediaContent: this class models the

concept of multimedia content. It is a simple class,

without subclasses, which formalizes its link with

the class representing file formats

(MultimediaFormat).

2) MultimediaFormat: represents the most common

file formats currently available in the Net. This class

has a two-level hierarchy. The first level represents

format file categorizations depending on the content

type they express. The second level is represented

within each categorization, where classes,

representing the actual formats, are located. Each

format is identified by its own extension.

3) Metadata: its subclasses represent every type of

metadata considered in the study of reference

standards and reference application context.

4) XMPtype: all properties concerning the Metadata

class and its subclasses have the XMPtype class as

codomain. It includes a number of classes which

represent the different data type the XMP standard

uses to describe information inside its tags. One

problem is that some applications avoid the complex

operation that stores information inside files. They

opt instead for executing it in external files or

databases, although that operation could lead to the

loss of metadata as well, when the same file is used

in different applications. XMP, for example, is one

of the standards that requires writing of its own

metadata set inside the file, but it is not the only

standard that enables this action. Every file format

often has its own blocks, different from the ones

XMP uses, to store certain metadata schemas. For

example, a JPEG image has some containers for

storage of the EXIF, IPTC-IIM, and Photoshop

standards.

Metadata are stored in different semantic groups

inside each block. For example, the following

groups can be found inside the XMP APP1 block:

Dublin Core, IPTC-Core, EXIF/TIFF; inside the

Photoshop APP13 block is the IPTC-IIM group.

This problem required a data reconciliation

which was performed through the mapping

technique. The creation of the mapping meant the

execution, where feasible, of a set of non-

automatable, strongly subjective operations.

The search for XMP tags that could map the ones

used on the analyzed platforms was an integral part

of our work.

We searched for tags with the same semantics as

the ones we needed, among those available in the

standards within XMP. This search was performed

with particular care so as to avoid mistakes due to

unclear or poor descriptions and consequent

semantic association mistakes.

Figure 1: XMP block's Schema.

3.2 Mapping of UGC Metadata

YouTube. A significant part of the metadata used by

YouTube was used in order to define the Ontology.

One of the problems we faced during the

mapping was reducing the semantics of certain tags

to a single representation.

Each tag was represented with all of its attributes

and subtags within the ontology. The significance of

the information YouTube associates with some tags

depends on the feed where they appear.

The set we chose to represent was the one related

to the video feed, i.e.:

id,published?,updated,category*,title,c

ontent?,link*,author?,gd:comments?,

media:group?,yt:statistics?,gd:rating?,

yt:location?,yt:recorded?,yt:accessCont

rol+ georss:where?, app:control?

This subset describes the information related to

videos, which are the main content of YouTube, and

has pieces of information that are to be taken into

account when complying to specifications, such as

comments and georeferencing information.

However, due to the importance of YouTube,

this subset was represented whole in the Ontology.

Non-mappable tags were created ex novo as well as

implication relations that could tie together

mappable tags with 'mapping' tags.

USING A STANDARDS-BASED APPROACH FOR A MULTIMEDIA KNOWLEDGE-BASE

Table 1: XML Schemas and related namespaces.

Schema Namespace

Prefix

Schema URL

Atom

Syndication

Format

Default

namespace

www.w3.org/2005/Atom

Open Search

Schema

openSearch

A9.com/-

/spec/opensearch/1.1

Media RSS media Search.yahoo.com/mrss

YouTube XML

Schema

Gdata.youtube.com/schemas

/2007

Google Data

Schema

gd schemas.google.com/g/2005

GeoRSS georss www.georss.org/georss

Geography

Markup

Language

gml www.opengis.net/gml

Atom Publishing

Protocol

app www.w3.org/2007/app

Google Data API

Batch Processing

batch

schemas.google.com/gdata/b

atch

The mapping happened in two different ways,

depending on whether the semantic correspondence

was direct (same meaning of information, and same

format, same data type as well) or indirect, that is to

say there was discordance in its form (same meaning

but different representation. In the direct case, we

exploited the feature by which it is possible to create

property hierarchies: each property can have its own

subproperties, which specialize their superproperties

just like a subclass specializes a superclass. This

means that an implication relation among nested

properties is in place: if the superproperties have a

domain and a codomain, those will be necessarily

inherited by their subproperties. Even on a visual

level, mapped tags will appear under the mapping

ones. Therefore direct mappings were performed by

assigning the mapped tag its mapping tag as

superproperty.

To make such operation clearer and the ontology

more readily accessible by users, every direct

mapping came together with an annotation of the

rdf:comment type with information related to the

'mapping' tag.

On the other hand, in the indirect case the

implication relation cannot be used, because the

information must be broken down in its elementary

parts first, and then those parts must be traced back

to direct mode. These steps are described inside the

rdf:comment associated to the mapped tag.

In particular it explains how to split and convert

the information, and where to store it.

Flickr. Our approach to Flickr was quite different

compared to YouTube. It was firstly because of how

metatada related to available content were managed,

and secondly due to the lack of documentation about

them. Initially Flickr used to equip its content with a

simple set of pure Exif data, so natively mappable in

the ontology because they strictly complied with the

standard.

Folksonomies. In the more recent years a reversal

took place, and metadata in Flickr started becoming

part of the so-called Folksonomies. As previously

discussed on section two, the usage of folksonomies

causes metadata not to belong to any kind of

hierarchy. They become unidentifiable in a

namespace and make recognition and mapping

impractical. For this reason the tags of Flickr not

included in the Exif standards were represented with

a class called 'FlickrFolkosomies' inside the

ontology. This class has, as a property, a set of tags

that allow to generate a Feed Atom, that in turn

includes all such information in bulk, non-

standardized.

Metadata belonging to standards but non-mapped

and lacking on the ontology Knowledge-base were

mapped and presented in the same way.

In particular, the set of unknown metadata or

metadata belonging to folksonomies must be stored

inside the Atom Syndication Format tag

atom:content. “This specification describes Atom's

XML markup vocabulary. Markup from other

vocabularies (foreign markup) can be used in an

Atom Document. Note that the atom:content element

is designed to support the inclusion of arbitrary

foreign markup.” (The Internet Society, 2005).

3.3 Mapping Example

We shall now consider the mapping applied to the

metadata related to the 'Hammamet' picture on

Flickr. The metadata associated to this picture by

Flickr are listed in Table 2.

These metadata are partly complying with the

Exif standard (and mapped with the typical rules of

the standard as such) and partly belong to

Folksonomies.

The above mentioned mapping rules were

applied, and part of the data were inserted, while the

rest was inserted in the FlickrFolksonomies class.

KMIS 2011 - International Conference on Knowledge Management and Information Sharing

Table 2: Tag EXIF.

Fotocamera Panasonic DMC-FS5

Esposizione 0,002 sec (1/640)

Aperture f/5.6

Lente 5.8 mm

ISO 100

Exposure Bias 0 EV

Flash Auto, Did not fire

Orientation Horizontal (normal)

X-Resolution 180 dpi

Y-Resolution 180 dpi

Software f-spot version 0.5.0.3

Date and Time

(Modified)

2009:08:21 19:02:51

YCbCr Positioning Co-sited

Exposure Program Landscape

Date and Time

(Original)

2009:08:19 08:07:14

Date and Time

(Digitized)

2009:08:19 10:07:14

Compressed Bits

Per Pixel

Max Aperture

Value

3.3

Metering Mode Multi-segment

Light Source Unknown

Color Space sRGB

Sensing Method One-chip color area

Custom Rendered Normal

Exposure Mode Auto

White Balance Auto

Digital Zoom Ratio 0

Focal Length

In35mm Format

33 mm

Scene Capture

Type

Standard

Gain Control None

Contrast Normal

Saturation Normal

Sharpness Normal

Image Quality High

Firmware Version 0.1.1.2

White Balance Auto

Focus Mode Auto

AFMode 3-area (auto)?

Image Stabilization On, Mode 2

Table 2: Tag EXIF (cont.).

Macro Mode Off

Shooting Mode Scenery

Audio No

Data Dump

(Binary data 8200 bytes, use -

option to

extract)

White Balance Bia

Flash Bias 0

Internal Serial

Number

AAAAAAAAAAAAAAAAAAAAAA

Panasonic Exif

Version

0260

Color Effect Off

Time Since Power

00:00:49.25

Burst Mode Off

Sequence Number 0

Contrast High

Noise Reduction Standard

Self Timer Off

Rotation Horizontal (normal)

Color Mode Normal

Optical Zoom

Mode

Standard

Conversion Lens Off

Travel Day n/a

World Time

Location

Home

Text Stamp Off

Program ISO n/a

Maker Note

Version

0121

Scene Mode Scenery

WBRed Level 1833

WBGreen Level 1054

WBBlue Level 1964

Flash Fired No

Compression JPEG (old-style)

Orientation Horizontal (normal)

As for the mapping, it was necessary to manually

enter what was not provided for by the scheme of

the ontology. We inserted the information related to

all properties and created the link amongst them and

between them and the various metadata so that they

could be represented univocally and no information

could be lost. In our example the first thing to be

created was, with the aid of the tool, the

USING A STANDARDS-BASED APPROACH FOR A MULTIMEDIA KNOWLEDGE-BASE

MultimediaContent class; the name 'Hammamet'

was then associated to it, exploiting the 'instance

browser. It could be noticed that, for the properties

previously created, the hasMetadataLocation and

doesExpress fields appear already compiled.

On the other hand, we had to define the elements

to insert in the hasMetadataDescription field and the

ExifSchema,UnknownMetadata,ExifSchemaHamma

met and UnknownmetadataHammamet instances.

The latter belongs to the class devoted to the

representation of unknown metadata belonging to a

standard.

At this stage, the ExifSchemaHammamet

instance could be filled out with all the fields

returned by the Flickr tool. In this way an univocal

correspondence between information and metadata

related to it was created.

The entire Exif schema must be checked in order

to know which tags of the picture are present or not.

We entered the missing data manually.

Once the values were ready to be entered into the

tags, we created a different data-type instance for

each data. Afterwards a Date_1-type instance was

created for the tiff:dateTime tag.

Since the data type belongs to the EXIF schema,

it requires some additional attributes for temporal

information

(

exif:subSecTimeDigitized,exif:subSecTi

meOriginalexif:subSecTime

); thanks to the

existing relations, the fields related to such attributes

were displayed as well.

4 CONCLUSIONS

The purpose of this work was to study, design and

create an ontology that could formalize the

multimedia content semantics and geocoded data,

starting from the most used standards in representing

that domain, especially the Adobe XMP standard.

The aim was to offer a structure enhanced with

semantics, that could serve as base support for the

creation of a software platform for web content

management.

Another powerful tool is represented by the same

shared standards: in fact, they guarantee

interoperability, i.e. the ability for various

technological systems and services to communicate

and exchange information among themselves and

with other systems, which is a feature of utmost

importance. Given the way the ontology was

organized and structured, we might think of its

future application as a support to a software platform

which would allow different subjects to develop

high-value services based on the input of multimedia

content in a context of semantic organization,

integrated by localization services.

The system could be accessible through mobile

devices such as PNAs (Personal Navigator

Assistant), that would use a geolocalization system

to know their location.

The platform, thanks to the modelled concepts,

could give users the chance to collect and add

contents originated from varied sources (websites,

web portals, local files) and to influence the value of

the contents though ratings, comments and

preferences. Thus contents could be gathered,

aggregated and geocoded, and then distributed to

each user.

Such a platform should clearly be provided a

powerful tool capable to “conform” every piece of

information about the added contents to the form

designated as representation standard within itself.

In other words, it must be able to map any kind of

metadata present in contents.

Once again the ontology we created would be an

impressive tool for fulfilling that requirement.

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USING A STANDARDS-BASED APPROACH FOR A MULTIMEDIA KNOWLEDGE-BASE