What is Virtual Reality?

“A high-end user interface that involves real-time simulation and interaction through multiple sensorial channels.” (vision, sound, touch, smell, taste)

ImmersiveComputer generated images will replace the real world viewThe generated images will react to the position and orientation of the user’s head

Non-ImmersiveUsers are able to view the virtual world however, they are still aware of the real worldi.e. viewing the VE through a monitor

HybridPermits the user to view the real world with virtual images superimposed over this viewAlso known as augmented reality

Type of VR systems

VR is an integrated trio of “Immersion”, “Interaction”

and “Imagination”

http://www.physorg.com/news/2011-04-virtual-reality-scent-human.html

Let watch some images / clips

http://www.youtube.com/watch?v=ZKw_Mp5YkaE

http://www.youtube.com/watch?v=he5mZX1sRXk&feature=related

http://www.joelfletcher.com/3d-nature.html

Input Devices:

Trackers, Navigation and Gesture Interfaces

3-D System of coordinates of a VR object

Virtual objects have 6 degreesof freedom (D.O.Fs):-three translations;-three rotations.

Input Devices

Trackers measure the motion of “objects” such as user’s wrist or his head vs. a fixed system of coordinates.

Technologies to perform this task:Mechanical trackers (special cases);Magnetic trackers (prevalent);Ultrasonic trackers (less used);Inertial/ultrasonic trackers (new).Vision-based trackers (new)

Input Devices

Input Devices

Tracker characteristics:Tracker characteristics:

Measurement accuracy

Measurement rate – Readings/sec;Sensing latency;Sensor noise and drift;Measurement repeatability;Tethered or wireless;Work envelope; Sensing degradation .

Input Devices

Tracker characteristics:Tracker characteristics:

Real object position

Accuracy

Resolution

Tracker position measurements

Input Devices

Tracker characteristics:Tracker characteristics:

Real object fixedposition

Signal noise

Time

Tracker data

Input Devices

Tracker characteristics:Tracker characteristics:

Real object fixedposition

Sensor drift

Time

Tracker data

Input Devices

Tracker characteristics:Tracker characteristics:

Real object position

Sensor latency

Time

Tracker data

Input Devices

Mechanical TrackersMechanical Trackers

Definition: A mechanical tracker consists of a serial or parallel kinematic structure composed of links interconnectedby sensorized joints.

Input Devices

Mechanical TrackersMechanical TrackersPros Use sensors imbedded in exoskeletons to measure position; Have extremely low latencies; Are immune to interference from magnetic fields and large metal objects; Cons But limit the user’s freedom of motion; Can be heavy is worn on the body

Input Devices

Exoskeletonstructure Interface

Withcomputer

Input Devices

Magnetic TrackersMagnetic Trackers

Definition: A magnetic tracker is a non-contact position measurement device that uses a magnetic field producedby a stationary TRANSMITTER to determine the real-time position of a moving RECEIVER element

Input Devices

Magnetic TrackersMagnetic Trackers

Use low-frequency magnetic fields to measure position;The receiver is attached to the tracked object and has three perpendicular antennas;Distance is inferred from the voltages induced in the antennas .. Need calibration

Input Devices

Polhemus Long Ranger tracking errors (Rutgers)

Metal in lab double ceiling

Ultrasonic TrackersUltrasonic Trackers

Definition: A non-contact position measurement device that uses an ultrasonic signal produced by a stationary transmitter to determine the real-time position/orientation of a moving receiver.

Input Devices

Ultrasonic TrackersUltrasonic Trackers

Use low-frequency ultrasound to measure position;Sound produced by a fixed triangular source (speakers);The receiver is triangular and attached to the tracked object and has three microphones;Distance is inferred from the sound time of flight;Sensitive to air temperature and other noise sources;Requires “direct line of sight”;Slower than magnetic trackers (max 50 updates/sec).

Input Devices

Ultrasonic tracker (Logitech)

Input Devices

Optical TrackersOptical Trackers

Definition: A non-contact position measurement device that uses optical sensing to determine the real-time position/orientation of an object

Input Devices

Optical trackers: a) outside-looking-in; b) inside-looking-out

Input Devices

Outside-looking in: Vicon MXOutside-looking in: Vicon MXUses 4 Mpixel cameras with own 120 LED array (infrared, or visible red). Accuracy 0.02 of a pixel, Camera has real-time onboard image processing (masking and thresholding) Resolution 2352x1728 @ 160 fps 8 cameras are connected to a MX net unit which then communicates with the PC

Input Devices

Outside-looking in: Vicon MXOutside-looking in: Vicon MX

MX Link connects several MX Net units for more cameras To interface with other devices like a force plate, sensing glove or eye tracker – use a MX control unit.User wears reflective markers (small spheres).

Inside-out optical tracker advantagesInside-out optical tracker advantages

The best accuracy is close to the work envelope. Very large tracking surface and resistance to visual occlusions (line of sight).

Input Devices

Hybrid Ultrasonic/Inertial TrackersHybrid Ultrasonic/Inertial Trackers

No interference from metallic objects;No interference from magnetic fields;Large-volume tracking;“Source-less” orientation tracking;Full-room tracking;A newer technology.

Input Devices

InterSense Stereo Glasses tracker (courtesy of Intersense Co.)

I-CubeAccel./gyro

Ultrasonic emitter

InterSense Stereo stylus tracker (courtesy of Intersense Co.)

Accelerometer

Ultrasonicemitter

Navigation and Gesture Input DevicesNavigation and Gesture Input Devices

Navigation interfaces allow relative

position control of virtual objects

(including a virtual camera); Gesture interfaces allow dextrous

control of virtual objects and interaction

through gesture recognition.

Input Devices

Navigation Input DevicesNavigation Input Devices

Are the Cubic Mouse, the trackball and the

3-D probe; Perform relative position/velocity

control of virtual objects; Allow “fly-by” application by controlling

a virtual camera.

Input Devices

The Cubic Mouse

Input Devices

VC 2.2 book CD

Trackballs

Input Devices

The Microscribe (Immersion Co.)

Input Devices

Gesture Input DevicesGesture Input Devices Are sensing gloves such as:

- Fakespace “Pinch Glove”

- 5DT Data Glove;

- The DidjiGlove

- Immersion “CyberGlove”Need calibration for user’s hand.

Input Devices

Finger Degrees of Freedom

Input Devices

Hand work envelope vs. interface type

Input Devices

The Pinch Glove (Fakespace Co.) - no joint measures, but contact detection

The glove interface: a) five-sensor version; b) newer design

A)

One optical fiber/finger

Roll/pitch sensing 5DT Data Glove Ultra

5DT Data Glove

100 datasets/sec, 12 bit A/D flexion resolution, wireless version transmits data at 30 m, needs calibration

The glove interface: a) 14-sensor version; b) wireless kit

Two sensors/finger plus abduction sensors

5DT Data Glove - continued

Two gloves use one Bluetooth 2.4 GHz transmitter on the user’s belt

5DT Data GloveInput Devices