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Spatiotemporal Information Processing No.2 3 components of Virtual Reality-1 Sensing System. Kazuhiko HAMAMOTO Dept. of Information Media Technology, School of Information and Telecommunication Eng., Tokai University, Japan. Today’s Contents. Virtual Reality and its 3 components (review) - PowerPoint PPT Presentation
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Spatiotemporal Information ProcessingNo.23 components of Virtual Reality-1Sensing System
Kazuhiko HAMAMOTO
Dept. of Information Media Technology,
School of Information and Telecommunication Eng.,
Tokai University, Japan
Today’s Contents
Virtual Reality and its 3 components (review)
Sensing System Tracker
Electromagnetic induction method Ultrasound method Optical method
Data Glove
Virtual Reality (review)
A computer will be able to process spatiotemporal information in next generation
To access the information, the computer will use human sense Ordinary behavior of person is also used as interface to
computer.
The human interface is “Virtual Reality”
Definition of “Virtual Reality” (review)
What is not actual, but has the same essence as actual thing
The world where we can access by the five senses and human behavior can be used as human interface directly
First proponent of “Virtual Reality” isJ.Lanier, USA, in 1987
3 elements of Virtual Reality (review) 3D Environment
3D virtual space is “natural” for human senses.
Real-Time Interaction Real time response of computer to action of
person Autonomy
Virtual space exists even if people (user) doesn’t exist,
Virtual space exists not only as human interface but independent of user.
Sensing system Detection of motion (head, eyeball, trunk, upper
limbs and lower limbs) in real 3D space and input to computer
Simulation system Creation of virtual space, and calculation of motion
of virtual objects and real-virtual matching
Display system (Realistic display) Display of not only visual but aural, tactile and
olfactory information, and stimulus of sense organs
3 components for Virtual Reality (review)
The relationship among 3 components (review)
Person
real space virtual space
Simulation system
Display system
Sensing system
computer
Sensing system What is done? and Where is it done? Measurement of Where
Coordinates and direction in 3D space 6 Degree Of Freedom : 6DOF
Coordinates : x, y, z Direction : Euler angle (yaw, pitch, roll) “Tracker”
Measurement of What Form of hand or body and their action Creation and display of their CG after the measurement Input of the intention of operating object
Sensing system : Euler angle
Definition of the order of axis rotation
“yaw, pitch, roll” means : 1st : z-axis, α[degree] 2nd : y-axis, β[degree] 3rd : x-axis, γ[degree]
in the right figure
Sensing System : Euler angle
Z
Y
X
z
y
x
100
0cossin
0sincos
cos0sin
010
sin0cos
cossin0
sincos0
001
(X,Y,Z) : World coordinate system(x,y,z) : Local coordinate system
Required condition of Tracker
Measurement of coordinates (x,y,z) and direction (yaw, pitch, roll), total 6DOF
6DOF information can be measured in real time The sampling rate is enough for representation of
user’s natural action The precision is less than one of sense of organ The range where Tracker can measure 6DOF can
cover the range of user’s action Tracker doesn’t restrict user’s action and it should be
free from environment
Sensing system : Tracker Tracker by electromagnetic induction
Use of electromagnetic induction 3 coils intersect perpendicularly each other Transmitter (fixed)
Generation of changing Magnetic flux Receiver (moving object)
Change of Linkage flux -> induced current in each of coils
Magnitude of induced currents is determined by position (x,y,z) and direction (pitch,yaw,roll) of the receiver.
6DOF of the receiver (moving object) can be detected by the induced currents.
Transmitter coil( fixed in the space )
Receiver coil(x,y,z,α,β,γ)
Generation and change of
Electromagnetic field
Induced voltageV=f (x,y,z,α,β,γ) depends on distance from transmitter and angle of receiver coil (amount of flux linkage)
Orthogonal coilV=f (x,y,z,α,β,γ)V=f (x,y,z,α,β,γ)
9 equation, 6 unknown information
Sensing system : Tracker
Transmitter(orthogonal
coil)
Receiver(orthogonal
coil)
Magnetic field
detector
drive circuit
Control unit
Output of 6DOF of receiver (X、 Y 、 Z 、 Roll、 Yaw、 Pitch)
Sensing system : Tracker
Advantages High precision
Coordinate : a few [mm], Angle : less than 1[deg] Small size and light weight Not suffer from physical obstacles
Weak points Narrow range of measurement, which depends on the size
of transmitter Suffer from magnetic material, for example, a desk made by
steel More the number of receiver is, less the sampling rate
becomes
Sensing system : Tracker
Sensing system : Tracker
3SPACE SYSTEM (POLHEMUS Inc.)
ISOTRAKII
Precision position 2.4 [mm] angle 0.75 [degree]
Area hemisphere whose radius is
76 [cm]
Data rate 30pts/s (2receiver)
Tracker2 transmitter
Receiver (fixed)
Receive USCalculationof distance
A transmitter is on the arc
A
BA transmitter is on the cross point of 2 arcs.
Measurement of B transmitter by the same matter
Angle of the Tracker can be detected
The distance is used as a radius
Sensing system : TrackerTracker by ultrasound
6DOF measurement by 3 transmitters and 3 receivers
Advantages Easy for measurement Not suffer from magnetic materials
Weak points Error by a change of sound velocity Suffer from the reflection and physical obstacles
Sensing system : TrackerTracker by ultrasound
Ivan Sutherland’s method 3 transmitter on user’s helmet
37, 38.6, 40.2kHz 4 receivers at each corner of the ceiling Continuous USs are transmitted, and
separated after the measurement. 12 patterns of phase shifts between
transmitted USs and received USs can be used for position detection
Sensing system : TrackerTracker by ultrasound
InterSense, Inc. IS-900 The wide range of tracking 3m×3m ~ 15m×15m The Precision
coordinate 4mm angle 0.2 ~ 0.4
[degree] The size of sensor
3cm ~ 4cm Data rate 180Hz
Sensing system : TrackerTracker by ultrasound
Markers emit by infrared rays and the markers are taken by high speed camera
Multiple camera and transmittance of infrared rays
High speed and high precision of measurement (6DOF in real time) can be realized
No restriction for user No limitation of the number of marker
Sensing system : TrackerTracker by Optics
Vicon Maximum 16million pixels , 10-bit gray scale Maximum shutter speed 2000FPS Maximum motion processing speed 120FPS A small marker can cover the wide range and measure the
information in detailed Resolution less than 5mm in practical case
http://crescentinc.co.jp/vicon
Sensing system : TrackerTracker by Optics
HoloStage, Immersive Virtual Environment in Tokai University
Sensing system : TrackerTracker by Optics
Sensing system : glove device
Input of user’s intention of manipulation of computer (virtual space manipulation)
Keyboard and mouse are not enough. Data glove
Input of motion of hand and finger Every joint has a sensor. The sensor measures bent angle. Precision is 0.5 [degree]. The form of hand is prepared in CG.
Attach a sensor to hand and finger, their deformation are measured Optical fiber method
The change of transmittance by the bent angle
VPL Inc , DataGlove, 1987 Conductive ink with cloth method
The change of resistance by a bend of finger Virtual Technologies Inc , CyberGlove
Sensing system : glove devicebasic principles
VPL Inc, DataGlove 1987 2 fibers for one finger No.1 and No.2 joint of a finger
are measured. = 10DOF The shape of a fiber is “U”. LED -> fiber -> phototransistor Approximation of the action by
CG
Sensing system : glove deviceexample of optical type
Conductive ink Liquid with particle who
has conductivity, for example, carbon
The resistance depends on the length of a sensor.
The length of a sensor depends on the bent angle.
Short = low resistance
Long = high resistance
The bent angle sensor by conductive ink
Sensing system : glove deviceexample of conductive ink type
Immersion Inc, CyberGlove The number of sensor : 18 or 22
18 models 2 sensor for each fingers, the
root of thums, the bent angle and twist of wrist
22 models 18 models + 4 No.1 angles of
each finger precision : 0.5 degree Refresh rate : 149 record/s
Sensing system : glove deviceexample of conductive ink type
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