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282 11. Navigation and Movement in VR
There is a close connection between the use of IK and the motion capture
and motion-tracking hardware discussed in Chapter 4. This is because IK
can predict the motion of parts of a linkage that have not been explicitly
tracked. It is especially useful in those cases where the tracked points relate to
human actions. For example, some dance steps might be captured by tracking
five markers on a human figure: two on the feet, two on the hands and the
other on the torso. A well-thought-out IK model will allow the motion of
ankles, knees, hips, wrists, elbows and shoulders to be simulated with a very
satisfying degree of realism.
And so, with all the theoretical detail explained with regards to creating
your own VR environment, it is now time to summarize all we have reviewed
before going on to the practical aspects of VR implementation.
Bibliography
[1] R. S. Ferguson. Practical Algorithms for 3D Computer Graphics. Natick, MA:
A K Peters, 2001.
[2] T.R.McCalla.Introduction to Numerical Methods and FORTRAN Program-
ming. New York: John Wiley and Sons, 1967.
[3] C. Welman. Inverse Kinematics and Geometric Constraints for Articulated Figure
Manipulation. MSc Thesis, Simon Fraser University, 1993.
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Summing Up
We have now reached the halfway point of the book. Back in Chapter 3, we
offered the opinion that VR has many useful applications with benefits for
mankind, but it also has its drawbacks, can be misused and can be applied in
situations where the original non-VR alternatives are still actually better. We
suggested that you (the reader) should make up your own mind whether VR is
appropriate or will work satisfactorily in an area that you may be considering
it for.
In the intervening chapters, we have explored the theory and technology
that delivers the most up-to-date virtual experiences. We have seen that a
VR system must interact with as many senses as possible to deliver a virtual
experience. To date, most research has been dedicated to delivering a realistic
visual experience. This is because sight is regarded as the most meaningful
human sense, and therefore is the sense that VR primarily tried to stimulate.
In addition, the process of sight is well understood, and most modern tech-
nology makes use of this knowledge, e.g., cameras and visual display devices.
Visualization technology is also very advanced because of its importance to
the entertainment industry (e.g., computer gaming). As a result, we can de-
liver highly realistic graphics in real time to the users of the VR environment.
Our ability to do this is also thanks to the huge revolution that graphics pro-
cessors have undergone. Now we are able to program these directly, and as
such we can achieve much more realism in our graphic displays.
However, when we try to stimulate even more senses in VR, e.g., sound
and touch, the experience exceeds the sum of its parts. This is a very
important point and is one reason why our guide covers such a broad spec-
trum of ideas, from computer graphics to haptics. Indeed, we try to hint
that the term rendering, so familiar in graphics, is now being used to present
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284 11. Summing Up
a 3D audio scene as well as painting haptic surfaces that we feel rather than
see. Sadly, this is difficult, and it may be a long time before it is possible
to render acoustically or haptically as realistic a scene as one can do
graphically.
Having described all the relevant technology involved in VR, we then
tried to give you an understanding of the internals of delivering the VR ex-
perience; that is, the software processing that must be undertaken to deliver
this experience. This is not a trivial topic, but if you want to build y our own
virtual environment then you should be able to grasp the basics of this, e.g.,
graphics rendering, the Z-buffer, lighting etc.
To complete our first section, we also introduced the concept of computer
vision. For some time, the sciences of computer vision (with its applications
in artificial intelligence and robotics) and computer graphics have been con-
sidered separate disciplines, even to the extent of using different notations for
expressing exactly the same thing. But, for VR and the increasingly impor-
tant augmented reality (AR), we need to bring these together and use both as if
they are one. For example, we can utilize computer vision to create VR from
pictures rather than build it graphically from mesh models. This is an ideal
way of creating the surrounding environment for certain VR experiences, e.g.,
walkthroughs.
Now, at the end of Part I, we hope that you have read enough on the
concepts of VR to help you answer whether VR is appropriate and suitable to
help enhance your own application.
The Future for VR
VR still has a lot of undiscovered potential for use in the future, but we should
notexpecttoomuchofit.
Ultimately, we would like to achieve a VR that is indistinguishable from
reality. But is this possible? Virtual humans whom you can touch and who
can touch you are always going to be figments of the imagination. Artificial
intelligence may one day offer virtual actors that can act autonomously and
intelligently, but they can’t be made to take physical form using any type of
projection system.
Is it possible to predict the future for VR? We think the answer has to be
no, but we do believe that today’s uses as summarized in Chapter 3 will only
form a small portfolio of the areas in which VR can play a part. Provided
we know our technological limitations and use the possibilities wisely, VR
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285
does offer a benefit to mankind, one that should equal the communications
revolution of the Internet. In fact, VR is really just a part of it.
Current Research Focus
In the short term, a high proportion of research effort in VR appears focused
along two pathways, haptics and distributed reality. The main technical chal-
lenges are in haptics.h e physical process of touch and feel is still not fully
understood, and our attempts to build equipment to interface with some of
its facets are bulky, look decidedly crude and frankly don’t, in many cases,
work very well either. When compared to the current graphics engines that
deliver startlingly realistic graphics, the realism of haptic rendering should be
a major focus for research.
Distributed reality is a popular topic in many VR research labs. For one
thing, it facilitates collaboration, with its obvious advantages in taking a con-
ference call to a new level of reality. The Internet is touching life in many
ways that could not have been imagined, and using it to link VR environ-
ments which appear simultaneously across the earth is easily possible and has
benefits yet to be quantified.
To say much more on either of these two topics now could make our
book look dated very quickly. We just urge you to keep an eye on these two
areas of research and development in VR, as they are likely to be the source
of the next big thing, whatever that might be.
Putting VR into Practice
To be of any real use, VR must be put into practice. This is where the sec-
ond part of the book and its CD resources come into play. At the center of
any VR application is a computer. It controls all the interface hardware and
provides a medium in which to represent the vir tual. The computer is now
probably the cheapest and most readily a vailable component in any VR sys-
tem. Even in its most basic form, the computer hardware is capable of sensing
in real time whilst simultaneously delivering graphics, audio and even haptic
control to almost any level of detail. What you can deliver in terms of reality
just depends on how much you are prepared to pay for the human interface
components and having the right software. We cannot (in a book) offer you a
low-cost and easy way of constructing the interface hardware, but we can offer
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286 11. Summing Up
you some exciting and useful software. In many cases, the same software can
be used to drive low-cost bespoke/experimental VR technology (as illustrated
in Chapter 4), right up to the most lavishly endowed commercial systems.
What we can offer you ar e some pieces of the software jigsaw for VR, which
you can place together with some basic interface components to achieve your
own VR experience. This is where Par t II comes in! So please read on.
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