BEYOND THE MOVING CAMERA: SYSTEMS DEVELOPMENT FOR INTERACTIVE IMMERSIVE EXPLORATION OF URBAN ENVIRON

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BEYOND THE MOVING CAMERA SYSTEMS DEVELOPMENT FOR
INTERACTIVE IMMERSIVE EXPLORATION OF URBAN
ENVIRONMENTS.

• Ian Bishop
• Centre for GIS and Modelling,
• University of Melbourne
• idbishop_at_unimelb.edu.au
•  
• Bharat Dave
• Faculty of Architecture, Building and Planning,
• University of Melbourne
• bharat_at_unimelb.edu.au

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Elements of Presence

• Illustrative
• Immersive
• Interactive
• Intuitive
• Intensive

From Sherman Judkins (1992)
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Illustrative

• VR offers information in a clear descriptive and
  illuminating way

Nakamae et al, 2001
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Immersive

• VR should deeply involve or absorb the user

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Interactive

• In VR, user and computer act reciprocally through
  the interface

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Intuitive

• Virtual information is easily perceived. Virtual
  tools are used in a human way.

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Intensive

• In VR the user encounters complex information and
  responds

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DEVELOPMENT
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OBJECTIVES

• Explore appropriate techniques for interaction
  with a virtual environment to enhance sense of
  place (presence) and the validity of assessments
  and responses.
• Develop some specific features for systems
  evaluation, namely
• link target objects to triggers within the
  virtual environment in order to allow users to
  open a door, call a lift, switch on a light etc
• attach directional sounds to still or moving
  objects
• animate light sources to change position, colour
  or intensity over time (e.g. sunset)

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HARDWARE

• 3 LINUX or IRIX computers
• 3 LCD projectors
• 3 flat screens (front or rear projection)

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SOFTWARE

• Built on IRIX Performer
• Loads objects in .obj, .dxf, .3ds, .flt and other
  formats
• Based on a scene file which defines
• Actions
• Triggers
• Targets
• The scene file also specifies
• Paths
• Sounds
• Lights

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Actions
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SOURCES TARGETS
define actions of targets TARGET LIFT STATE
UP1 ACTION FOLLOWPATH LIFT_UP ACTION
FOLLOWXYZ 31.8 24.1 0.8 STATE DOWN1 ACTION
FOLLOWPATH LIFT_DOWN ACTION NEXTSTATE
define targets TARGET LIFT TYPE
SELECT FILEREF lift.obj TRANSLATE 0.0 0.0
26.0 END TARGET SOURCE LIFT_BUTTON TYPE
SELECT FILEREF lift_button.obj TRANSLATE 0.0
0.0 26.0 END SOURCE
link sources to targets SECTION
TRIGGERS SOURCE LIFT_BUTTON TARGET
LIFT TARGET LIFT_BUTTON END TRIGGERS
define paths SECTION PATHS PATH
LIFT_UP FILEREF lift_up.path END PATH
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SYNCHRONISATION

• Three client instances are executed on three
  separate machines. A server program is executed
  somewhere on the local area network.
• One of the client applications is the control
  which transmits messages (such as position,
  orientation, action events, key presses) to the
  server, which passes them to the other clients
• Visual synchronisation requires that the three
  instances update the display at exactly the same
  time.
• Each client renders the next frame into a hidden
  buffer and sends a message to the server when it
  has finished.
• The server waits for all three clients to
  indicate they have rendered the current frame.
• The server sends a 'swap buffer now' message to
  every client.
• All clients swap their hidden buffer to the
  foreground at the same time.  

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Sounds

• The server checks the ID of messages that arrive.
  It also listens for packets that hold the
  viewer's position (XYZ) and orientation (HPR)
  information.
• The server keeps track of each sound source in a
  table and uses OpenAL (Open Audio Library -
  (http//www.openal.org/home/) to create a 3D
  sound environment. The library uses various
  filters, applied to each of the speakers
  separately, to achieve this.
• This way the sound samples are heard to be coming
  from the direction of the source in the scene.
• These OpenAL libraries are available for Windows,
  Macintosh and Linux operating systems, but not
  for IRIX OS, so the server must be run on Linux
  for this functionality.

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An example

• Play the movie..

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ISSUES CHALLENGES

• Modelling information
• different needs of precision-oriented geometric
  modeling community and that of real-time
  interaction and visualisation community have led
  to divergent solutions
• Interaction paradigms
• With viewers immersed in 3D space, 2D interaction
  paradigms may or may not be the most appropriate
  ways to interact with such environments
• Application specific knowledge
• scene geometry may come from one database whereas
  event dependency and activation may be driven by
  separate domain specific knowledge, e.g. traffic
  flows
• Application of rule-based behaviour
• the presence of, and interactions with, other
  people condition much of our experience of urban
  spaces
• User perception and participation
• there is a distinction between information that
  is meaningful and useful, and that is detailed
  and complete

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Directions

• Interactive design
• The ability to combine design and visualisation
  tasks at one-to-one scale in immersive
  environments will allow a richer and immediate
  feedback cycle in more responsive designs.
• Temporal changes
• construction assemblies, traffic distribution,
  pollution dispersion, deforestation, etc., can be
  simulated and studied in a more systematic
  manner.
• Participatory design
• The presence of multiple viewers implies multiple
  control devices and procedures within the virtual
  environment.
• Travel and tourism
• a different mode in which to access and
  experience places and cultures that may not
  easily accessible

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CONCLUSION

• Just begun to explore the potential of virtual
  environments for fun, profit, learning,
  self-awareness, decision support or applications
  unknown.
• Commercial developers are leading the way
  technologically but their conceptual horizons are
  bound by entertainment-related objectives.
• Urban planners and managers have real problems
  but are generally not a large enough market for
  specialized developments (c.f. What if?
  CommunityViz)
• People without profound software and systems
  skills may be unaware of the possibilities.
• We hope that the efforts described here will
  narrow this divide

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thanks