An idea that was born from the research areas of hypertext
If you consider a traditional text based thesaurus, it organises words
into entries. Each entry represents a concept (much like an
everything2 node) and lists synonyms for the concept. Given this
structure, you can look up other synonyms for a concept, or find which
concepts are described by a given word.
Text based information retrieval systems often include a thesaurus. This
allows queries containing the word "car" to retrieve documents
containing the word "automobile". The thesaurus enables automatic
synonym substitution to be used.
A multimedia thesaurus is an attempt to adopt a traditional thesaurus
approach but with information represented in several media. The concepts
may be the same as a thesaurus, but the multimedia synonyms
are very different.
For example, a multimedia thesaurus entry for the concept of "table" may
have the word "table", a picture of a table, a sound clip of someone
saying "table" and a 3D computer model of a table. During a query, any
of these representations may be matched against to arrive at the
concept, and any representation may be used as a result for the query.
Clearly, such an approach requires multimedia matching techniques to
allow pictures and sounds and other representations to be compared.
This is a whole research area in itself and is very much an unsolved
problem in the general case. One problem is the way the same object can
look very different when viewed from different angles. The computer
can't match two different views of the same object easily.
A multimedia thesaurus can alleviate this problem by including several
views as representations of a concept. This way, matching against any of
the views will allow the same concept to be visited. It can be used as an approach to object classification.
The utility of the thesaurus can be enhanced by associating different
information with the entries. If documents are associated with entries
that represent the concepts they describe, then the thesaurus can be
used as an index to the documents. Alternatively, relationships can be
stored between the entries themselves, allowing the thesaurus to become
a semantic network.