topical media & game development
Given an information space we may turn it into
an information hyperspace, that is, following [Spaces]
the logical information space may further be structured in a logical information hyperspace, where the clues become hyperlinks that provide directional information, and the information space can be navigated by the user following directional clues.
In other words,
information is chunked, and each chunk is illustrated
or made accessible by an example (hypernode).
Now, what exactly does information hyperspace mean?
To answer this question, let's briefly look at the history of
hypertext and hypermedia.
Vannevar Bush' seminal paper As we may think
may be regarded as the origin of what is known as
hypertext with which, even if you don't know the phrase,
every one of you is familiar, since it is (albeit in a rather
simple way) realized in the web.
The phrase hypertext was invented by Ted Nelson
(not patented, as far as I know),
who looked for a less constraining way
to organize information then was common in
the educational system he grew up with.
But before that, Douglas Engelbarth, who
incidently invented the mouse, developed the Augment
system to, as he said, boost the human intellect.
What for, you may ask.
Let me quote the series of flashes
that Engelbarth went through, according to Dust or Magic [Magic]:
- 1945 -- Vannevar Bush (Memex) -- as we may think, [Bush]
- 1963 -- Douglas Engelbart (Augment) -- boosting the human intellect [Engelbart]
- 1980 -- Ted Nelson (Xanadu) -- everything is intertwinkled, [Nelson]
- flash 1: we are in trouble (human mankind)
- flash 2: we need to boost mankind's ability to deal with complex urgent problems
- flash 3: aha, graphic vision surges forth of me ...
- flash 4: hypermedia -- to augment the human intellect
- flash 5: augment (multimedia) workstation -- portal into an information space
classification of hypermedia
Perhaps it is good to know that Vannevar Bush
wrote his article when working for an information agency
in the second world war period.
From that perspective, we can easily see that hypermedia
(combining hypertext and multimedia)
were thought of an instruments of intelligence.
Basically, hypermedia systems must be able to deal with:
- components -- text, graphics, audio, video
- links -- relations between components
- presentation -- structured display
Far from being a definition, this characterization
gives some insight in what functionality hypermedia systems
Recall that dealing with complex information is what
hypermedia is all about.
Is this a natural way to deal with information?
Just think about how you are taught to deal with
information and how you actually go about with it.
Speaking about Ted Nelson, [Magic] observed that
he realized that this intertwingularity was
totally at odds with the education system he spent so long in
and had been so uncomfortable with.
Quoting Ted Nelson himself from his book Literary Machines:
A curriculum promotes a false simplification of any subject,
cutting the subject's many interconnections and leaving
a skeleton of sequence which is only a charicature
of its richness and intrinsic fascination.
Judge for yourself.
Would you prefer to have an 'immersive' course in
multimedia rather than a more or less ordered
collection of abstractions?
True enough, the visions of the pioneers of hypermedia
Nevertheless, the concept of hypermedia,
that is non-linear media with
machine-supported links, or 'text' as a network,
found an application in a large variety of systems, see [Hypertext].
classification of hypermedia systems
- macro-literary systems -- publishing, reading, criticism
- problem exploration tools -- authoring, outlining, programming
- browsing systems -- teaching, references, information
- general hypermedia technology -- authoring, browsing, collaboration
- embedded hypermedia -- CASE, decision support, catalogs
An example of a hypermedia system that has
extensively been used in education, for
example biology and chemistry classes,
is the Brown University Intermedia
system of which supports so-called information webs,
consisting of documents and links,
that could both be retrieved by specifying attribute,
allowing in this way for respectively both filtered content and
An interesting aspect of this system is that the user
may create maps, that is structures containing
documents and links, which form a personalized
version of the web of information for a specific user,
superimposed on the information space offered by the system.
Dexter Hypertext Reference Model
After many years of developing ideas and exploring
implementations, one group of experts in the
field came together and developed what is commonly
known as the Dexter Hypertext Reference Model,
named after the location, actually a pub, where the meetings were held.
The Dexter model offers an abstract description
It made a distinction between components, anchors within components
and links between components, attached to anchors.
The model was meant as a reference standard against
which existing and future hypertext systems could
Components have the following attributes:
- content -- text, graphics, video, program
- attributes -- semantic description
- anchors -- (bi-directional) links to other documents
- presentation -- display characteristics
The Dexter Hypertext Model has been criticised
from the beginning.
Among others, because compound documents,
that is documents having subcomponents,
where not adequately dealt with.
And also because it did not accomodate
multimedia (such as video) content very well.
In practice, however, the Dexter model has proven
to be even somewhat overambitious in some respects.
For example, the web does (currently) not support
bi-directional links in a straightforward manner.
Amsterdam Hypermedia Model
When looking for alternatives, a Dutch multimedia research
group at CWI proposed to extend the Dexter model
with their own multimedia model (CMIF), an extension for
which they coined the name Amsterdam Hypermedia Model.
Let's look at the (CMIF) multimedia model first:
(CMIF) multimedia model
- data block -- atomic component
- channel -- abstract output device
- synchronization arc -- specifying timing constraints
- event -- actual presentation
What strikes as an immediate difference with respect to
the hypertext model is the availability of channels,
that allow for presenting information simultaneously,
and so-called synchronization arcs,
that allow the author to specify timing constraints.
Also, events are introduced in the model to deal with
With respect to authoring, the model
supports a declarative approach to specifying sequential
and parallel compounds, that is in what order specific things
must be presented and what may ocuur simultaneously.
Again, channels may be employed to offer a choice in the presentation,
for example a dutch or english account of a trip in Amsterdam,
dependent on the preferences of the (human) viewer.
The Amsterdam Hypermedia Model (AHM) extends the Dexter Hypertext
Reference Model in a rather straigthforward way with channels
and synchronization arcs.
Amsterdam Hypermedia Model
- contents -- data block
- attributes -- semantic information
- anchors -- (id, value)
- presentation -- channel, duration, ...
Obviously, the difference between Dexter and AHM is primarily
the more precise definition of presentation characteristics,
by introducing channels as in the (CMIF) multimedia model.
Another (major) difference lies in the
characterization of compounds.
Each compound has one or more children, or subcomponents.
Subcomponents may act as the source or destination
of synchronization arcs.
Each component obtains a start-time, that may result
from parallel or sequential composition
and synchronisation arcs.
Another interesting concept introduced by
the Amsterdam Hypermedia Model is the notion of context.
What happens when you click on a link?
Does everything change or are only some parts affected?
Then, when you return, does your video fragment start anew
or does it take up where you left it?
Such and other issues are clarified in the
Amsterdam Hypermedia Model, of which we have omitted many details here.
It is perhaps interesting to know that the
Amsterdam Hypermedia Model has served as a reference for the
SMIL standard discussed in section 3.2.
If you want to know more about
the Amsterdam Hypermedia Model, you may consult
[Hypermedia] or [AHM].
example(s) -- hush
In the hush
we explore a variety of hypermedia applications.
In fact already in 1994 we developed a SGML-based
browser with applets in Tcl/Tk.
Somehow, we did a lot with music with optimistic titels such as
Bringing music to the Web, [Music] and more pessimistic ones such
as Jamming (on) the Web, [Jamming].
The acronym hush stands for hyper utility shell.
Many of the projects with hush were student projects,
in which we studied operational support for hypermedia applications.
Although we used SGML for markup, we did not have
any specific document model, as in [CMIF].
An overview and rationale of hush is given in [OO].
A significant part of the hush software is being
reused in the ViP system, that is discussed in section
4.3, albeit with an entirely different
research directions -- computational models
Today, hypermedia functionality is to some extent embedded
in almost all applications.
However, to realize the full potential of hypermedia,
and in effect the networked multimedia computer,
there are still many (research) issues to be resolved.
To get an impression of the issues involved,
have a look at the famous seven hypermedia research
issues formulated by Halasz.
- search and query -- for better access
- composition -- for imposing structure
- virtual structures -- on top of existing structures
- computation -- for flexibility and interaction
- versioning -- to store modification histories
- collaborative work -- sharing objects with multiple users
- extensibility and tailorability -- to adapt to individual preferences
See [Hypermedia], section 2.3 for a more extensive description.
Although the research issues listed above were formulated
quite early in the history of hypermedia,
as a reflection on the requirements for second-generation
hypermedia systems, they remain valid even today.
Without going into any detail with respect to the individual
research issues, I rather wish to pose the grand encompassing
research issue for the networked multimedia computer:
What is the proper computational model underlying
hypermedia or, more generally, for applications
that exploit the networked multimedia computer
in its full potential?
Some directions that are relevant to this issue will be given in
[3-3] which deals with
the multimedia semantic web.
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