Using Large Displays for Virtual Environments

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Using Large Displays for Virtual Environments

• Yonca Haciahmetoglu
• CS6724 Display Wall User Interfaces
• Spring 2006

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Todays Papers

• Patrick, E. et.al. (2000). Using a large
  projection screen as an alternative to
  head-mounted displays for virtual environments.
  Proceedings of the SIGCHI conference on Human
  factors in computing systems, pp. 478 485
• Tan, D.S., Gergle, D., Scupelli, P., Pausch, R.
  (Accepted for publication, 2005). Physically
  Large Displays Improved Performance on Spatial
  Tasks. To appear in ACM TOCHI.
• Bouguila, L., Ishii, M., and Sato, M. 2002.
  Realizing a new step-in-place locomotion
  interface for virtual environment with large
  display system. In Proceedings of the Workshop
  on Virtual Environments 2002 , ACM International
  Conference Proceeding Series, vol. 23.
  Eurographics Association, Aire-la-Ville,
  Switzerland, 197-207.

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Paper I

• Using a large projection screen as an
  alternative to head-mounted displays for virtual
  environments

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Head Mounted Displays -HMDs

• Immersive experience
• - Cost
• Large projection screens may be effective
  substitutes for immersive displays such as HMDs.
• Differences in spatial knowledge in 3 viewing
  conditions
• HMD
• Large projection screen
• Desktop monitor

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Some points

• Question the level of immersion actually needed
  for effective cognitive mapping
• increasing field of view leads to perceptual,
  visual, and motor improvements in various
  navigation performance tasks
• Overall, wider fields of view are desirable for a
  wide variety of spatial tasks
• restricting field of view leads to perceptual,
  visual and motor decrements in various kinds of
  performance tasks

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Spatial Knowledge

• Acquisition of spatial knowledge
• Landmark knowledge
• Route knowledge
• Survey knowledge
• VR - educational and training tool
• Provides an opportunity for people to gain
  spatial knowledge for an environment other than
  the one in which they are physically located

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Spatial Cognition

• Cognitive maps
• internal, mental representations of spatial
  environment
• A component of spatial knowledge
• WHY is this internal representation important?
• Basis for human interaction with the world,
  guiding peoples decisions and interactions.
• HOW to build a cognitive map?
• Paper map v.s.Cursory navigation through
  environment
• Field of View
• How much of the world can be seen at a time
• has large impact on underestimating the distances
  both in real world and in VE
• Smaller FOV - people think things are closer then
  they actually are

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Immersion and Presence

• Immersion
• The feeling of isolation from the real world
• movies (no interaction), games (high level of
  interaction)
• Presence
• The extent to which a persons cognitive and
  perceptual systems are tricked into believing
  they are somewhere other than their physical
  location.

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Why (not) HMDs?

• HMD
• Can produce an experience high in immersion and
  presence
• Most effective way to gain accurate spatial
  knowledge for a VE
• Cognitive maps formed in HMD perform
  significantly better than cognitive maps learned
  by viewing VE on desktop monitor
• Users spent more time looking around
• WHY different than desktop monitor?
• additional perceptual cues provided by peripheral
  vision
• Peripheral vision plays critical role in learning
  the spatial layout of the environment - important
  for educational and military applications of VR
• The ability to look around
• Why not?
• However may cause simulator sickness
• Equipment is expensive and uninviting to use -
  neck strain

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Experiment

• 2 approaches for navigation
• Participants are allowed to freely explore
• Participants view a scripted presentation of a VE
• Procedure
• Standard spatial ability pretest
• Surface Development Test
• Exploration of two Ves
• Practice VE - to learn how to use steering wheel,
  to get used to the landmarks
• Experimental VE
• Virtual amusement park - groundkeepers
• Location and orientation of the entrance booths
• Posttest to discover what participants could
  remember about locations of landmarks in the
  second VE
• Foam squares representing the entrance booths
  placed on a white paper

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Results

• The hypothesis that the HMD condition should show
  better performance then large screen and desktop
  monitor was not supported
• No significant difference between two conditions,
  but significantly different than desktop monitor
• Earlier supporting results were due to additional
  display capabilities
• Participants did not move their head that much
  while using HMD
• Even with HMDs increased peripheral vision and
  capability to allow participant to freely look
  around, large screen still leaves participants
  with comparable spatial knowledge.

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Results

• Screen is more consistent and reliable
• smaller variance, lower mean placement in error
  scores
• Why Large screen outperformed HMD?
• Images projected into big screen may appear more
  real - more accurate judgments of relative
  position
• Large screens
• have the potential for multi-user
• Cost less
• Does not require labor-intensive installations

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Paper II

• Physically Large Displays Improved Performance
  on Spatial Tasks

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Overview

• 4 experiments
• comparing the performance of users working on
  large projected wall display to that of users
  working on standard desktop monitor
• First 2 experiments
• Large displays (even with constant visual angle)
  perform better on mental rotation tasks
• Large displays are immersing users within problem
  space biasing them into using more efficient
  cognitive strategies
• Next 2 experiments
• To show the presence of these effects with more
  complex tasks, such as 3D navigation and mental
  map formation and memory

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Questions

• How physical affordances of the large displays
  fundamentally affect human perception and
  thought?
• How does the size of the screen affect task
  performance?
• Other factors (visual angle, resolution,
  brightness, contrast, color, and content) are
  held constant
• Are the effects of large displays independent of
  other factors that may induce immersion or
  increase performance?
• Wider FOV can increase immersion

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General Setup for Experiments

• 2 displays for each experiment
• Resolution 1024x768
• Frame rate 60Hz
• Fixed FOV
• Wider FOV causes wider retinal image, and slows
  the speed of rotation

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Experiment 1

• Why is the performance differ in spatial
  orientation tasks?
• One explantion the choice of cognitive
  coordinate systems used to perform the task
• Remember that there was no significant
  difference in reading task in an earlier work
• Task mental rotation
• presentation, degree of immersion, and level of
  performance have been extensively measured for
  those tasks
• Guilford-Zimmerman test

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Experiment 1 - Hypotheses

• Hypothesis 1a
• Simple instructions and training prior to the
  test are sufficient to bias users into adopting
  either the egocentric strategy or the exocentric
  one when they perform the task.
• Hypothesis 1b
• The egocentric strategy is more efficient than
  the exocentric one for this spatial orientation
  task.

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Experiment 1- cont

• Egocentric
• First person view
• Users imagine rotating their bodies within
  environment
• Exocentric
• Third-person view
• Users imagine objects rotating around each other
  in space
• Evidence in psychology research
• Egocentric strategies are more efficient for real
  world tasks
• Users become more immersed in the task on the
  large display - they were more likely to adopt
  the egocentric strategy
• Egocentric rotations are quicker

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Results

• 2x3x2x2
• display size, instruction type, position, gender
• Users performed better when they used egocentric
  strategy than exocentric
• Simple instructions and training were sufficient
  to bias users into adopting one or the other
  strategy
• Display size affects the choice
• In the absence of explicit strategy, user seem to
  have chosen an exocentric one when working with
  small displays, and an egocentric one when
  working with large displays

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Experiment 2

• Hypothesis 2
• Large displays bias users into using egocentric
  strategies and do not increase performance on
  intrinsically exocentric tasks for which
  egocentric strategies are not useful.
• Task type
• Object-centric problems have been described as
  inherently exocentric
• 2x2x2
• Display size, position, gender

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Results

• Users performed no differently on any of those
  tasks whether using small or large display

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Results- cont

• There was no reason to believe that imagining
  their bodies within the problem space due to
  object-centric nature of the stimuli
• We must be very careful in applying the findings
  as large display benefits only apply to tasks
  that can be performed more effectively using
  egocentric strategies
• Next experiments
• Incrementally increase the complexity of spatial
  abilities used in order to see if current effects
  continue to be robust
• Use fairly rich dynamic 3D VE and incrementally
  increase the complexity by adding cues such as
  landmarks and textures in order to see how the
  effects hold up in presence of other cues
• Test for the reliability of large display when
  the user actively interacts with the VE.

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Experiment 3

• Earlier work
• Users perform 3D navigation tasks requiring path
  integration more efficiently on large displays
• 3D navigation is a complex cognitive task
  requiring the use of a series of interrelated
  spatial abilities
• This experiment
• Include a mental map formation and memory task
• The user explores the virtual world in order to
  build a cognitive map of the environment
• The users then navigates to several targets as
  quickly as they can - using the cognitive map
  they build
• 2x2 - display size, interactivity (passive
  viewing, active joystick)

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Experiment 3 - Hypotheses

• Hypothesis 3a
• Users perform better in mental map formation and
  memory tasks when using physically large displays
  due to the increased likelihood that they adopt
  egocentric strategies.
• Hypothesis 3b
• Users perform better in the path integration task
  when they are interactively moving themselves
  through the virtual environment.
• Hypothesis 3c
• The effects induced by physical display size are
  independent of those induced by interactivity.

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Experiment 3 - Results

• Fairly complex task requiring the use of numerous
  spatial skills
• Map formation and memory task benefited from
  having users adopt an egocentric frame of
  reference while navigating
• Users benefited from active control
• It helped users learn and remember environments
  more effectively
• Effects of interactivity were still independent
  of effects induced by size.

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Experiment 4

• VEs in Experiment 3 were still fairly sterile and
  controlled.
• They did not contain any landmarks or textures.
• Can other factors contribute to effects observed
  before?
• Hypothesis 4
• Even in an environment crafted with cues such as
  distinct landmarks and rich textures to be
  realistic and memorable, users perform better in
  mental map formation and memory tasks when using
  physically large displays due to the increased
  likelihood that they adopt egocentric strategies.

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Experiment 4 - design

• 2x2 (display size, difficulty)
• Learning phase (Active)
• Recall phase

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Experiment 4 - Results

• Benefits of large displays are independent of the
  cues that may be used in real-world virtual
  environment to increase immersion and
  memorability, such as distinct landmarks and rich
  textures.

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General Discussion

• Physically large displays immerse users and bias
  them into adopting egocentric strategies
• The effects caused by physically large displays
  seem to be independent of other factors that may
  induce immersion or increase performance
• Large displays offer the potential to improve
  performance on a fairly broad range of taks.
• It is interesting that these results exist at
  all