Realtime 3D Computer Graphics Virtual Reality

Realtime 3D Computer GraphicsVirtual Reality

Virtual Reality Input Devices

Realtime 3D Computer Graphics / Virtual Reality – WS 2005/2006 – Marc Erich Latoschik

VR input devices! Special input devices are required for interaction,navigation and

motion tracking (e.g., for depth cue calculation):

1. Motion Trackers: Position and orientation of a reference system in 3D requires to measure 6 Degrees of Freedom (DOFs).

2. 3D Mice/Wands etc. : Specialized devices for point and click WIMP1-style metaphors have to account for additional DOFs.

3. Joint sensors: Sensors which measure movement of user’s joints (Also possible with trackers and inverse kinematics).

4. Props: Real placeholders for virtual objects.5. Movement effect sensors: Measure the effect user movement

has to the surrounding (no kinematics involved).6. Skin sensors, neural interfaces, bio-sensors: Measure skin

resistance, brain activity and other body related data.

…and hybrid devices.1WIMP: Windows, Icons, Menu, Pointer


VR input devicesInput is measured by a multitude of physical and biological

principles, e.g.,1.electro-magnetism2.optics (marker/marker less, visible spectrum/infrared)3.electrics (voltage, impedance, electrical flow,…)4.acoustics (ultrasound,…)5.inertia

Input devices produce data...•...discrete event based

(buttons, state changers).•...continuously

(discrete but continuously sampled).


VR input devices

6DOF Magnetic tracker & DataGlove

• Electromagnetic tracker• used to be most common

see: “put-that-there” (Bolt, 1980)• Transmitter

• Creates three orthogonal low-frequency magnetic fields

• Short range version: < 1m• Long range version: < 3m

• Receiver(s)• Three perpendicular antennas. • Distance is inferred from the

currents induced in the antennas.

- Noisy – requires filtering.- Affected by metal – requires non-linear

calibration.- Wireless versions expensive.

Transmitter

Receiver


• Inertial trackers !(Intersense IS-300)

+ Less noise, lag- Only 3 DOFs (orientation)• Use gyroscopes and accelerometers

• Hybrid trackers(e.g.,Intersense IS-600/900)

• inertial (orientation)• acoustic (position)

• Acoustic trackers• Uses ultrasound• Typical setup for 3 DOF:

3 microphones and1 speaker• Distance is inferred from the

travel time of the sound+ No interference with metal+ Relatively inexpensive- Line of sight issues- Sensitive to air temperature

and certain noises Logitech Fly Mouse

VR input devices


VR input devices

• Optical marker based tracker• marker reflects IR light• Combined to unique spatial

configuration per tracked position+ No interference with metal+ Low latency+ High resolution- Line of sight issues

(more cameras help)

6DOF optical tracker by ART


• 3D mice/wands• Several buttons and sensors

for selection of binary states and/or continuous state changes (e.g., potentiometers).

• Often hybrid devices for additional position/orientation.

VR input devices

tracked wand

space orb

ring mouse


VR input devices• CubicMouseTM

• First 12 DOF input device• Tracks position and rotation of rods

using potentiometers• Other shapes and

implementationspossible

• Mini Cubic Mouse• …

pictures courtesy of IMK Fraunhofer Gesellschaft


Sensors: 20/suit

100 updates/sec3 meters rangefrom base unitResolution<2 mmand <.2 degrees

Electronic unit(2 hours battery life)

Wireless suit (Ascension Technology)

VR input devices• Data Gloves

• Used to track the user’s finger movements.

• For posture and gesture detection.• Almost always used with a tracker

sensor mounted on the wrist• Common types:

• Body suites • Used to track the overall body

movement• Angles measured by resistance or• by inverse kinematics based on certain

body points

5DT Glove (left)5/16 sensors

• CyberGlove (right)• 18/22 sensors

• here hybrid modification for flexion and pinch


Head-propCourtesy of Hinkley et al.

VR input devices

ShapeTape-propcourtesy of Balakrishnan et al.

Cyberglove with haptics

Treadmill types(e.g. bicycles)

! …all the preceding and/or Speech Input

• continuous vs. one-time recognition• choice and placement of microphone• training vs. no training• handling of false positive recognition• surrounding noise interference• Can complement other modes of interaction

! " multi-modal interaction (by, e.g., additionally including gesture processing which benefits from the VR sensory equipment)

Fiktion: Interaktion


The Ultimate Display

„The ultimate display would, of course, be a room within which the computer can control the existence of matter. A chair displayed in such a room would be good enough to sit in. Handcuffs displayed in such a room would be confining, and a bullet displayed in

such room would be fatal. With appropriate programming such a display could literally be the

Wonderland into which Alice walked.“

(Sutherland 1965)

Fiktion: Interface für das „Ultimate Display“?

Fiktion: Results of physical contact


References• Bolt, R. A. (1980): Put That There: Voice and Gesture at the Graphics Interface.

In: Computer Graphics 14/3, (pp. 262-270)• Bühl, Achim (1997): Die virtuelle Gesellschaft. Politik, Ökonomie und Kultur im Zeichen des Cyberspace.

In: Gräf, Lorenz/ Krajewski, Markus (Hrsg.): Soziologie des Internet. Handeln im elektronischen Web-Werk, Frankfurt/M. /New York: Campus, 39-59.

• Gibson, William (1984): Neuromancer (first print)• Gibson, William (1999): Neuromancer, 9. Aufl., München: Heyne 1999 • Okoshi, T. (1976): Three-Dimensional Imaging Techniques, Academic Press, New York. • Peters, G. (2000). Theories of Three-Dimensional Object Perception - A Survey. Recent Research

Developments in Pattern Recognition, Transworld Research Network.• Sutherland, I.E. (1968): A Head-Mounted Three-Dimensional Display.

In: AFIPS Conference Proceedings, Vol. 33, Part I, pp. 757-764.

Realtime 3D Computer Graphics Virtual Reality

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