Teil 3: VR – Eingabegeräte · Teil 3: VR – Eingabegeräte Virtuelle Realität Wintersemester...

Virtuelle Realität

1

Teil 3:VR – Eingabegeräte

Virtuelle RealitätWintersemester 2007/08

Prof. Bernhard Jung

Prof. B. Jung Virtuelle Realität TU Freiberg

Overview

Continuous input devicesTrackerData gloves

Discrete & hybrid input devices Mouse-type input devices

MiscellaneousPlatformsSpeech…

Virtuelle Realität

2


Information Flow in VR-Systems

Source: Sherman & Craig, 2005


Virtual Reality Experience Source: Sherman & Craig, 2005

Virtuelle Realität

3


User input to the virtual world

User monitoring is the real-time monitoring of the participant's actions in a VR experience

Continuous tracking of user movements (body tracking). allows the system to render and display the virtual world from the user's egocentric perspective -- providing the effect of physical immersion.

Discrete user-initiated inputsallows the user to indicate to the system that an action should be takene.g. pressing a button or speaking a command to the system


Discrete / event-basedContinuous / sampledHybridsMiscellaneous input

speechlocomotion devices

Input device characteristics

Virtuelle Realität

4


Generate one event at a timeEvent queueExamples:

buttonskeyboardspinch gloves

Discrete input devices


Continuous input devices

Produce steady stream of dataSampled at various times by the system for “snapshot” of stateExamples:

trackersdata glovespotentiometers

Virtuelle Realität

5


Tracking systems

Measure position and/or orientation of a sensor6 degrees of freedom in space

Most VEs track the head and the hand(s) Spatial input devices

free-space interaction

Tracked real objects resembling virtual objectsMotion capture


Electromagnetic Tracker

6DOF Magnetic tracker & DataGlove

6 DOF tracking (position & orientation)Transmitter

Creates three orthogonal low-frequency magnetic fieldsShort range version: < 1mLong range version: < 3m

Receiver(s)Three perpendicular antennas Distance is inferred from the currents induced in the antennas

DistortionsNoisy – requires filteringAffected by metal – requires non-linear calibration

Rather large sensors (1-2cm)

Transmitter

Receiver

Virtuelle Realität

6


Wireless suit (Ascension Technology)Sensors: 20/suit

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

Electronic unit(2 hours battery life)


Optical Trackerpassive

IR light reflecting markerCombined to unique spatial configuration per tracked position

activeIR light emitting markerSequential activation: trivial identification of single markersrequires cabling & batteries

2 or more IR camerasAdvantages

No interference with metalLow latencyHigh resolution

DisadvantagesLine of sight issues (more cameras help)

6DOF optical tracker by ART

Virtuelle Realität

7


Optical Tracker

6DOF optical tracker by ART


Real-Time Motion Capture

www.ptiphoenix.com

Virtuelle Realität

8


Mechanical Tracker

Very accurate and preciseVery fastMechanical linkage places an unnatural inertia on the userMechanical linkage can prevent the user from moving to some locationsForce feedback can be integrated into the system

Video: HMD SutherlandBoomPhantom


Uses ultrasoundTypical setup for 3 DOF

3 microphones1 speaker

Distance is inferred from the travel time for the sound

Triangulation allows the location of each microphone/speaker to be determined

AdvantagesNo interference with metalRelatively inexpensive

DisadvantagesLine of sight issuesSensitive to air temperature and certain noises

Logitech Fly Mouse

Acoustic Trackers

Virtuelle Realität

9


Inertial trackers

Intersense IS-300Less noise, lagOnly 3 DOFs (orientation)Use gyroscopes and accelerometers

inexpensiveCan lose accuracy over time

a gyroscopesource: wikipedia


E.g. Intersense IS-600 / 900inertial (orient.)acoustic (pos.)

E.g. Ascension HyBirdoptical (position + orientation)inertial (orientation)

Hybrid Trackers

Virtuelle Realität

10


E.g. Nintendo Wii Remote optical position & orientation tracking

uses built-in one-megapixelimage sensor

+ stationary sensor bar with 8 IR LEDs

+ orientation tracking using acceleration/tilt sensors

used when device is pointed away from sensor bar

Hybrid Trackers

wikipedia

nintendo-europe.com

wii.nintendo.com


Tracking Technology: Pros and Cons Overview

Acc

urac

y

Late

ncy

Drif

t

Line

Of

Sigh

t

Wire

less

Sens

or W

eigh

t

Sens

or S

ize

Magnetic - - + + - + - Optical (active) + + + - 0 + +

Optical (passive) + + + - + + - Acoustic 0 + + - + - - Inertial - + - + 0 0 0

Acoustic / Inertial 0 + + +/- 0 - -

(based on Kuhlen & Assenmacher)

Virtuelle Realität

11


Used to track the user’s finger movementsfor gesture and posture communication

Almost always used with a tracker sensor mounted on the wristCommon types

CyberGlove18 sensors22 sensors

5DT Glove 5 sensors16 sensors

Require calibrationtime-consuming processresults often not perfect

Sensor readings do not correspond directly to joint angles requires nonlinear mappingparticularly difficult: Thumb rotation

Data Gloves

Immersion Cyberglove II, 22 sensors

5DT Data Glove, 16 sensors


Mattel / Nintendo Power Glove (1989)

Image: wikipedia

Virtuelle Realität

12


Optical Finger Tracking

Extension of motion tracking

accurate finger tip positionsreliable calculation of joint angles

simple calibration

line-of-sight issuesparticularly tricky: bimanual interactionmore cameras help

ART, www.ar-tracking.de

PTI, www.ptiphoenix.com


Continuous and discrete inputExamples

Button device + trackerFlex & PinchRing mouseLCD tabletCubic MouseSpaceballTracked PDA

Hybrid devices

Virtuelle Realität

13


Buttons + Joystick + 6 DOF Tracking

Tracked Wands


Space MouseRing Mouse (pictured)Fly Mouse(pictured)

Mouse Type Devices

Virtuelle Realität

14


SpaceballSpaceMouseSpaceOrb

Potentially tracked

SpaceNavigator

Stationary Devices


3Dconnection SpacePilot

Virtuelle Realität

15


The Cubic Mouse

Fraunhofer IMK, Bernd Fröhlich & John Plate


Cubic Mouse

First 12 DOF input deviceTracks position and rotation of rods using potentiometers

Other shapes andimplementationspossible

Mini Cubic Mouse…

Virtuelle Realität

16


Hinkley et al., 1994

Props

A physical object used to represent some manipulableobject in a virtual worldThe physical properties (shape, weight, texture, center of gravity, solidity) give a limited amount of haptic feedback, and often suggest how the device is used (e.g. putter) Real nature of props allows user to easily manipulate the object (e.g. hand it to another user).

Head propCar prop…


Tracking & interaction with handheld devices

tracked PDA

tracked stylusbuttons + stylus + 6DOF trackingtablet PC

Object selection (left) and manipulation (right)

work by Stefan Conrad, 2007

Virtuelle Realität

17


Platforms

Larger physical structures used to interface with virtual worlds (the place where the user sits or stands) Can themselves represent some portion of the virtual world Can be generic or specific Several common platform types


Ring Platform

Generic Typically used with head-based displaysTypically has a waist-high rail surrounding the participant Often used with handheld props

Ascension Spacepad

Virtuelle Realität

18


Kiosk Platform

Booth-like structure the user stands/sits at (like an arcade machine) Generally has physical controls mounted on it Often designed to be easily relocatable


Ambulatory platforms

Treadmill or stair-stepping machine Designed to provide realistic travel through the virtual world Physical exertion through leg motion gives proprioceptic feedback

www.virtusphere.com

Onmidirectional Platformwww.vsd.bz

Virtuelle Realität

19


Vehicle platforms

Designed to seem as though you are riding in the cockpit of some craft Realistic controls panels are provided Large flight simulators are a familiar example Often used in theme-park VR systems


Input devices with Haptics

cyberglove with haptics

Haptic Workstation

Vibro-tactile feedback

All pictures: www.immersion.com

Virtuelle Realität

20


www.measurand.com

Other input devices – Shape Tape


Other input devices – Position Tracking for minimal invasive surgery

Ascension 3D Guidance™ Tracker

"3D Guidance tracks the position and orientation of one or more tiny sensors, enabling real-time guidance of medical instruments for minimally invasive, image-guided procedures. Sensors, ranging in diameter from 1.8 mm to 0.3 mm, are typically embedded in the distal tip of catheters, scopes and probes. Measurements are unaffected when used in close proximity to intravascular ultrasound arrays."www.ascension-tech.com

Virtuelle Realität

21


Other input devices –Neural (muscular) tracking methods

Means of sensing body part movement relative to other body parts(e.g. curling the hand into a fist). Has not been explored to a large degree in VR systems


Audio Input - Speech Recognition

Speech is a natural means of communicating information Can complement other modes of interactionmulti-modal interaction

How does computer know you're talking to it? push-to-talk name-to-talk look-to-talk

Issues to considercontinuous vs. one-time recognitionchoice and placement of microphonetraining vs. no traininghandling of false recognitionsurrounding noise interference

Not good when speaking can interfere with other operations Very good when hands are occupied with other tasks

Teil 3: VR – Eingabegeräte · Teil 3: VR – Eingabegeräte Virtuelle Realität Wintersemester...

Documents

Transcript of Teil 3: VR – Eingabegeräte · Teil 3: VR – Eingabegeräte Virtuelle Realität Wintersemester...