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Explore the foundations of virtual reality interaction, from immersive to non-immersive systems, input devices, and task types. Learn about user properties affecting task performance and delve into virtual reality models and body hierarchies.
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Lecture 3: Interaction Klaas Werkman Arjen Vellinga
Contents • Immersive Systems • Virtual Model • Body Model • Non-immersive systems • Input devices • Tasks in Virtual Reality Lecture 3: Interaction
Interaction Lecture 3: Interaction
Types of tasks • Navigation / Locomotion • Object manipulation Lecture 3: Interaction
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 Lecture 3: Interaction
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 Lecture 3: Interaction
Immersion • The displayed information surrounds the participant • The display is extensive • The display is inclusive • The display is vivid Lecture 3: Interaction
Example immersive system • Head Mounted Display (HDM) Lecture 3: Interaction
Another example Lecture 3: Interaction
Example semi-immersive system • Cave Automatic Virtual Environment (CAVE) Lecture 3: Interaction
Difficulties interaction human and system • Gulf of execution • Gulf of evaluation Lecture 3: Interaction
Difference between CAVE and HMD with respect to interaction between human and system. • HMD: Virtual body displayCave: Real body is visible Lecture 3: Interaction
Body Model • Description of the interface to the Virtual Environment System • Geometric description of the body drawn from an egocentric point of view Lecture 3: Interaction
H-Anim body hierarchy Lecture 3: Interaction
Motion tracking • Animation Lecture 3: Interaction
Six properties of tracking systems • Accuracy • Resolution • Range • Total system lag • Update rate • Robustness Lecture 3: Interaction
Object manipulation example Lecture 3: Interaction
Locomotion Lecture 3: Interaction
Collision Detection • Preventing object intersection • Object pair collision detection; several tests to achieve this. Lecture 3: Interaction
Exhaustive test Lecture 3: Interaction
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. Lecture 3: Interaction
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. Lecture 3: Interaction
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. Lecture 3: Interaction
General Collision Detection • With n objects n2 possible pairs of objects. • Discard as many pairs as possible by spatial partitioning Lecture 3: Interaction
Spatial Division example Lecture 3: Interaction
Non-immersive Systems • Desktop Virtual Reality • Fish Tank Virtual Reality Lecture 3: Interaction
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 Lecture 3: Interaction
6D Mouse Lecture 3: Interaction
Space ball Lecture 3: Interaction
Tablet Lecture 3: Interaction
Glove • VPL Glove • Cyberglove Lecture 3: Interaction
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) Lecture 3: Interaction
Taxonomy of Mackinlay Lecture 3: Interaction
Three types of composition • Merge composition • Layout composition • Connection composition Lecture 3: Interaction
Magic Wand • Animation Lecture 3: Interaction
Selection Lecture 3: Interaction
Object Manipulation • Translation • Rotation Lecture 3: Interaction
Translation Lecture 3: Interaction
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 Lecture 3: Interaction
Locomotion Lecture 3: Interaction
Locomotion • Scale • Accuracy Lecture 3: Interaction