1. Klaas Werkman Arjen Vellinga
Lecture 3: Interaction
Klaas Werkman
Arjen Vellinga

2. Contents Immersive Systems Non-immersive systems Input devices
Virtual Model
Body Model
Non-immersive systems
Input devices
Tasks in Virtual Reality
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3. Interaction
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4. Types of tasks Navigation / Locomotion Object manipulation
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5. User properties that may influence the performance of a task
User experience
Domain knowledge
Technical aptitudes
Left-handed/right-handed
Physical properties such as age, gender, size, stature
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6. Virtual Reality Model
Participant should be immersed within the virtual world
Participant should be able to directly manipulate the virtual world
The environment should be intuitive to use
The environment should have a natural set of interaction metaphors
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7. Immersion The displayed information surrounds the participant
The display is extensive
The display is inclusive
The display is vivid
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8. Example immersive system
Head Mounted Display (HDM)
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9. Another example
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10. Example semi-immersive system
Cave Automatic Virtual Environment (CAVE)
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11. Difficulties interaction human and system
Gulf of execution
Gulf of evaluation
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12. Difference between CAVE and HMD with respect to interaction between human and system.
HMD: Virtual body display Cave: Real body is visible
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13. Body Model
Description of the interface to the Virtual Environment System
Geometric description of the body drawn from an egocentric point of view
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14. H-Anim body hierarchy
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15. Motion tracking
Animation
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16. Six properties of tracking systems
Accuracy
Resolution
Range
Total system lag
Update rate
Robustness
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17. Object manipulation example
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18. Locomotion
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19. Collision Detection Preventing object intersection
Object pair collision detection; several tests to achieve this.
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20. Exhaustive test
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21. Basic rejection test 1
Each scene element is surrounded by a bounding sphere. Two objects cannot overlap if the distance between the two bounding sphere centers is greater then the sum of the radii of the bounding spheres.
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22. Basic rejection test 2
Separating plane test: Two objects cannot collide if any plane can be found where all the points of one object lie on one side and all the points of the other object lie on the other side.
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23. Basic rejection test 3
Bounding Box Range Test: Two boxes can overlap in 3D if and only if both their x-ranges overlap and both their y-ranges and both their z-ranges overlap.
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24. General Collision Detection
With n objects n2 possible pairs of objects.
Discard as many pairs as possible by spatial partitioning
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25. Spatial Division example
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26. Non-immersive Systems
Desktop Virtual Reality
Fish Tank Virtual Reality
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27. Characteristics of input devices
Degrees of freedom
Spatial resolution
Sampling rate and system lag
Resistance (isotonic or isometric)
Body centered interaction
Number of user supported
Size, weight, comfort and mobility
Costs
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28. 6D Mouse
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29. Space ball
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30. Tablet
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31. Glove
VPL Glove
Cyberglove
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32. Taxonomy of Mackinlay The classification is: Linear / Rotary
Position, Rotation / Force, Torque
Relative / Absolute
Direction
Sensitivity (1 = discrete, 10 = small range, 100 = large range, INF = continuous)
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33. Taxonomy of Mackinlay
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34. Three types of composition
Merge composition
Layout composition
Connection composition
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35. Magic Wand
Animation
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36. Selection
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37. Object Manipulation Translation Rotation March 9th 2005
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38. Translation
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39. Locomotion Metaphors
Scene-in-hand — The scene itself is slaved to the input device
Eyeball-in-hand — User viewpoint is controlled via direct manipulation of virtual camera
Flying vehicle control — The input device provides the controls for the vehicle such as velocity and rotation
Real world control — Walking, walking-in-place
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40. Locomotion
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41. Locomotion
Scale
Accuracy
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