So, we can rephrase our problem as
how can we give access to the 'Dam square' information space
But now we forget one thing.
The idea underlying the last scenario is
that we somehow realize a seamless
transition from the real life experience to
the information space.
Well, of course, we cannot do that.
So what did we do?
1
Look at the screenshot from our virtual context
prototype.
You can also
start the VRML demo version that is online, by
clicking on the screenshot.
What you see is (a model of) the Dam square, more or
less as it was in 2001.
In the lower part, you see a panel with paintings.
When you click on one of these painting,
your viewpoint is changed so that you observe the real
building from the point of view from which the
painting was made.
Then using the controls to the right of the panel, you can overlay
the real building with a more or less transparent
rendering of the painting.
You can modify the degree of transparency by
turning the dial control.
You may also make the panel of paintings invisible,
so that it does not disrupt your view of the Dam
and the chosen overlay.
In other words, we have
a VR model of Dam square and
a selection of related paintings from the Royal Museum, that are
presented in aa panel from which the user can choose a painting.
We deploy viewpoint adjustment, to match the selected painting,
and we use
overlay of paintings over buildings, in varying degrees of
transparancy, to give the user an impression of
how the differences between the scene depicted in the
painting and the actual scene in (the virtual) reality.
virtual context
- VR model of Dam square
- selection of related paintings fromRoyalMuseum
- viewpoint adjustment, to match painting
- (transparent) overlay of paintings over buildings
We have chosen for the phrase virtual context
to characterize this prototype,
since it does express how
virtual reality technology enables us to relate
an information space to its original context.
From the perspective of virtual reality, however,
we could also have characterized our prototype
as an application of augmented virtual reality,
since what we have is a virtual reality model
of a reallife location that is augmented with information
that is related to it,
(almost) without disrupting the virtual reality
experience.
In summary, we may characterize our approach as follows.
augmented virtual reality
- give user sense of geographic placement of buildings
- show how multiple objects in a museum relate to eachother
- show what paintings convey about their subject, and how
Considering the fact that many city-scape paintings of
Amsterdam have been made,
many of which are in the Royal Museum,
and that paintings may say many things about their subject,
we believe that our approach is viable
for this particular instance.
The augmented virtual reality approach would also
qualify as a possible approach to cultural heritage
projects, provided that sufficient pictorial
material is available or can be reconstructed.
Although we were quite satisfied with what we accomplished,
there are still many things that can be done
and also a number of open problems.
problems
- organised guided tours
- account for buildings that no longer exist
- change temporal context
- allow user queries as input
Guided tours are a wellknown phenomenon.
But how to place them in our virtual context is
not entirely clear.
As another problem, our approach does not seem
suited to account for buildings that do no longer exist.
Another thing we have to study is how to change the temporal
context, that is for example change from a model
of the dam in 2001 to a model of the Dam in 1850.
We would then also like to have 'viewpoint transitions' over space and time!
Finally, to give better access to the underlying
information space we must also provide for
textual user queries,
and find an adequate response to those queries.
VRML
To realize our prototype we used VRML,
which limits us to medium quality
desktop VR.
At this stage, VRML is a good option, since it is a relatively
stable format with a reasonable programmatic model.
In short, what VRML offers is
VRML
- declarative means for defining geometry and appearance
- prototype abstraction mechanism
- powerful event model
- relatively strong programmatic capabilities
Although VRML allows for writing models
(including geometry and appearance) using a plain text
editor, many tools support export to VRML.
As a consequence, often tools are used to create
more complex models.
In addition,
VRML allows for defining prototype abstractions, so reuse
of models and behavior can be easily realized.
Defining dynamic behavior involves the routing of
events that may come from a variety of built-in sensors
(for example a TimeSensor for animations)
to scripts or so-called interpolators, that allow
for the manipulation of geometry and appearance
parameters of the model.
In particular, the use of scripts or the
External Authoring Interface (EAI),
that allows for defining behavior in Java,
is essential for realizing complex behavior.
Summarizing, VRML is a sufficiently rich
declarative language for defining 3D scenes,
with a relatively powerful programming model for
realizing complex behavior.
Some may think that VRML is dead.
It isn't.
The underlying model is endorsed in both
the X3D and RM3D standards,
simply since it has proven its worth.
2
research directions -- augmented virtuality
Given an information space, there is a duality
between information and presentation.
For an audience or user to be able to digest
a presentation, the amount of information must be limited.
Effective presentation, moreover, requires the use of proper
rethorics (which may be transcoded as ways of presenting)
that belong to the medium.
Using VR, which is (even in its desktop format)
a powerful presentation vehicle,
one should always beware of the question what is it good for?
Generally one may ask, what is the added value of using VR?
In an abstract fashion the answer should be,
to bridge the gap between information content and presentation.
Or, in other words, to resolve the duality between
information and presentation!
Let's look at an example, a site about archeology,
announced as a site
offering Virtual Archeology.
Perhaps it is good to bring to your attention that the
virtual, in Computer Science, means nothing but another
level of indirection to allow for a (more) flexible usage
of entities or objects.
See [OO], section
1.2.
virtual archeology
- variety of archeological sites
- various paths through individual site
- reconstruction of 'lost' elements
- 'discovery' of new material
- glossary -- general background knowledge
For a site about archeology, virtual means the
ability to present the information in a number of ways,
for example as paths through a particular site,
with the possibility to explore the reconstruction of lost
or perished material, and (for students) to discover new perspectives
on the material.
In addition, for didactic reasons there may also be
a glossary to explain concepts from archeology.
Now, how would you construct such a site
about virtual archeology?
As a collection of HTML pages and links?
It seems that we can do better, using VR and rich
interaction mechanisms!
So, what is meant by augmented virtuality?
Nothing that hasn't been expressed by the notion
of augmented virtual reality, of
which an example has been given in this section.
The phrase augmented virtuality itself is just
one of those potentially meaningless fancy phrases.
It was introduced simply to draw your attention
to the duality between information and presentation,
and to invite you to think about possible ways to
resolve this duality.
(C) Æliens
04/09/2009
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