FIT5900 : Interactive
In the previous lecture:
- Animation is all about putting in lots of hard work to make pictures that
seem to move.
- Animation may help you get across your message in ways which no other
medium can quite manage.
In this lecture:
- Why make an interactive virtual world?
- What issues do you need to consider when making a virtual world for people
to interact with?
- What technologies are available to help you make & display a virtual
- Do a web search for Myst, Riven,
Tomb Raider Doom/Quake or if you have an old Apple somewhere try Zork &
Beyond Zork, Transylvania, Hitch-Hikers Guide
to the Galaxy... or any of countless other virtual world type games (of course
there are plenty for the PC too).
- Also play around with the VRML models below and search the web for others.
Whilst you can probably read about these virtual worlds, there is nothing quite
There is no experience quite like being there and...
Looking at things from different locations
Hearing things from different locations
Bumping into things
...being there allows you to sense the place.
- Virtual Reality (VR) aims to provide this experience synthetically
by fooling a viewer into experiencing a space where there is none.
- Often digitally synthesized, animated images are presented to a VR
Early text and text / still-image based adventure games like Zork,
Beyond Zork, The Hobbit & Transylvania
were extraordinarily adept at transporting the player to another world
for real-world hour after hour.
- A still image creates a kind of virtual reality and may be used to
give the illusion of space.
- To make a virtual world "inhabitable" consistency is vital!
- Consistent behaviour (objects / characters)
- Consistent location (for navigation)
- Consistent interaction
An inconsistent world is impossible to inhabit comfortably!
- It is also beneficial if there is a purpose to one's visit to a virtual
- Explore (only if the world warrants it!)
- Solve a puzzle (only if the puzzle warrants it!)
- Chat with other inhabitants (only if the inhabitants warrant it!)
- Provide sophistication of interaction...
- Via a story tied in with a puzzle... hence the success of text based
- Complex and rewarding interaction through the inclusion of other human
inhabitants... hence the success of Doom, Quake, Internet chat rooms etc.
- Complex artificial agents are also becoming viable inhabitants
for interesting worlds. (Space Invaders & Pacman ghosts were just the
3 - Dimensional Computer Graphics
- The domain of Computer Graphics concerns itself with Image Synthesis...
the modelling of illusory light reflected, transmitted and absorbed by objects
which themselves do not exist, like these cubes...
- Most 3D graphics is produced using off-the-shelf software with a GUI that
even a newcomer to computers can decipher after a few years of training, headaches,
heart aches, lost clumps of greying hair, broken relationships etc.
- 3D software packages may provide means
- Modelling - the process of specifying the geometric properties
of an object.
Usually performed through a GUI allowing the user to select basic primitives
(cones, spheres etc.) and modify their geometry by various means as well
as decorate them with textures and connect them in hierarchies.
At this stage synthetic lights are also added to the model for the rendering
- Animating - the process of specifying the time varying properties
of a model.
Usually performed by a keyframing process where the model is posed
at various times and the computer mathematically determines where the
model ought to be positioned between these key frames.
- Rendering - the process of synthesizing images of a model.
Usually a computationally expensive process where imaginary light rays
are bounced off the imaginary model at each time an image is required
and for each pixel in the image to determined the colour visible to a
viewer at that point in space.
Virtual Reality Markup Language (VRML)
- A compact means of describing 3D virtual worlds usable on the WWW.
- A computationally intensive thing to display in a web browser.
Display requires a VRML plugin such as CosmoPlayer.
- Users can interact with the three-dimensional world or model using the mouse.
Take a look at this NASA
model (requires a VRML plugin for display).
- Objects in the world may be animated.
- Objects in the world may be hotlinked to other VRML scenes.
Quicktime Virtual Reality (QTVR)
- A means of illustrating a world (real or imaginary) using a panaoramic
photograph or rendering 'stitched' into a cylinder. (Other similar methods
stitch images into complete spheres)
- Not a computationally expensive thing to display in a browser!
- Users can interact with the pseudo three dimensional world using the mouse.
- Objects in the world can't really be animated.
- Locations on the image may be hotlinked to other QTVR scenes.
Of course even without these fancy technologies you can reveal a space! Have
a look at the Opera National de Paris...
just pretend you want to make a booking to the opera and then click on the map
of the opera house. (Shame about the scrolling status bar text on the main page
Now if you're looking for something to do... try playing this large, crazy
online adventure game
(just click the READ link)!
This lecture's key point(s):
- Virtual worlds are a cheap and nasty substitute for real places and experiences.
- They can also be the only way some people will ever experience a space...
especially if the space is of your own invention!
- Virtual worlds can also provide a safe environment for training.
- Consistency is perhaps the most important aspect of virtual world design.
courseware | FIT5900
Alan Dorin & Jon McCormack 1999,2000