Effects of Handling Real Objects and Avatar Fidelity on Cognitive Task

Performance in Virtual Environments

Benjamin Lok

University of North Carolina at Charlotte

Samir Naik

Disney VR Studios

Mary Whitton, Frederick P. Brooks Jr.

University of North Carolina at Chapel Hill

March 25th, 2003

Current ImmersiveVE Approaches

• System has limited shape and motion information of real objects.

• Most objects in the VE are purely virtual– User– Tools– Parts

• Most virtual objects are not registered with a corresponding real object.

Ideally

• Would like:– Real objects in the VE, including accurate

virtual representations, or avatars– Virtual objects responding to real objects– Haptic feedback– Correct affordances– Constrained motion

• Example: Unscrewing a virtual oil filter from a car engine model

Dynamic Real Objects

• By tracking and modeling dynamic objects (change shape and appearance) would– Improve interactivity– Enable visually faithful

virtual representations

Previous Work: Incorporating Real Objects into VEs

• Non-Real Time– Virtualized Reality (Kanade, et al.)

• Real Time– Image Based Visual Hulls [Matusik00, 01]– 3D Tele-Immersion [Daniilidis00]

• Augment specific objects for interaction– Doll’s head [Hinkley94]– Plate [Hoffman98]

• How important is to get real objects into a virtual environment?

Previous Work: Avatars• Self - Avatars in VEs

– What makes avatars believable? [Thalmann98]

– What avatars components are necessary? [Slater93, 94, Garau01]

• VEs currently have:– Choices from a library– Generic avatars– No avatars

• Generic avatars > no avatars [Slater93]

• Are visually faithful avatars better than generic avatars?

Object Reconstruction System

• System takes n live camera images.

• At each frame, generates a view of the visual hull of the real objects from the user.

• It is combined with the virtual environment

• 15-18 fps• Allows incorporation of

dynamic real objects into a virtual environment

Spatial Cognitive Task StudySpatial Cognitive Task Study

Study Motivation

• Effects of– Interacting with real objects– Visual fidelity of self-avatars

• On– Task Performance

• For spatial cognitive manual tasks

Spatial Cognitive Manual Tasks

• Spatial Ability– Visualizing a manipulation in 3-space

• Cognition– Psychological processes involved in the

acquisition, organization, and use of knowledge

Task Performance Hypotheses

Real Objects: Participants will complete a spatial cognitive manual task faster when manipulating real objects, as opposed to virtual objects only.

Avatar Fidelity: Participants will complete a spatial cognitive manual task faster with visually faithful self-avatars, as opposed to generic avatars.

Task

• Manipulated identical painted blocks to match target patterns

• Each block had six distinct patterns.

• Target patterns:– 2x2 blocks (small)– 3x3 blocks (large)

Measures• Task performance

– Time to complete the patterns correctly – If errors were made:

• Participants were notified• Participants continued until all errors were corrected

• Other factors– (After experience) Steed-Usoh-Slater Sense of

Presence Questionnaire (SUS) (larger study)– (Before experience) spatial ability– (Before and after experience) simulator sickness

Conditions

• All participants did the task in a real space environment.

• Each participant did the task in one of three VEs.

Real Space

Purely Virtual

Hybrid

Vis. Faithful Hybrid

Conditions

Avatar Fidelity

GenericVisually

faithful

Interact with

Real objects

HE VFHE

Virtual objects

PVETask performance

Task performance

Real Space Environment

• Task was conducted within a draped enclosure

• Participant watched monitor while performing task

• RSE performance was a baseline to compare against VE performance

Purely Virtual Environment

• Participant manipulated virtual objects• Participant was presented with a generic avatar

Hybrid Environment

• Participant manipulated real objects• Participant was presented with a generic avatar

Visually-Faithful Hybrid Env.

• Participant manipulated real objects• Participant was presented with a visually faithful avatar

Task Performance Results

Small Pattern Time (seconds) Large Pattern Time (seconds)

Mean S.D. Mean S.D.

Real Space (n=41) 16.8 6.3 37.2 9.0

Purely Virtual (n=13) 47.2 10.4 117.0 32.3

Hybrid (n=13) 31.7 5.7 86.8 26.8

Visually Faithful Hybrid (n=14) 28.9 7.6 72.3 16.4

Small Pattern Time Large Pattern Time

T-test p T-test p

Purely Virtual vs. Vis. Faithful 3.32 0.0026** 4.39 0.00016***

Purely Virtual vs. Hybrid 2.81 0.0094** 2.45 0.021*

Hybrid vs. Vis. Faithful Hybrid 1.02 0.32 2.01 0.055

* - significant at the =0.05 level ** - =0.01 level *** - =0.001 level

Task Performance Results

Debriefing Responses• They felt almost completely immersed while performing the task.

• They felt the virtual objects in the virtual room (such as the painting, plant, and lamp) improved their sense of presence, even though they had no direct interaction with these objects.

• VFHE and HE participants felt tactile feedback of working with real objects improved their performance and sense of presence.

• They felt that seeing an avatar added to their sense of presence.

• PVE and HE participants commented on the fidelity of motion, whereas VFHE participants commented on the fidelity of appearance.

• VFHE participants reported getting used to manipulating and interacting in the VE significantly faster than PVE participants.

Conclusions

Study Conclusions• Interacting with real objects provided a quite

substantial performance improvement over interacting with virtual objects for cognitive manual tasks.

• Avatar fidelity does not appear to affect cognitive task performance.

Handling real objects makes task performance and interaction in the VE

more like the actual task.

Future Work

• Improved Object Reconstruction System– model fidelity– lag and latency (could improve results)

• Further studies to illuminate:– Effect of real objects and avatar fidelity on:

• Sense of Presence

– Expand on the relationship between avatar kinematic fidelity and visual fidelity

ThanksCollaborators

Dr. Larry F. Hodges

UNC-CH Effective Virtual Environments

Object Reconstruction SystemI3D2001 and I3D2003

For more information:http://www.cs.uncc.edu/~bclok/research/vr2003

Funding Agencies The LINK Foundation

NIH (Grant P41 RR02170)

National Science Foundation

Office of Naval Research