NS 484 Virtual Reality Final Review

Virtual Reality (VR)

Inducing targeted behavior in an organism by using artificial sensory stimulation, while the organism has little or no awareness of the interference.

Open-loop system

Sensory stimulation does NOT depend on actions taken by the organism.

Closed-loop system

Sensory stimulation depends on actions taken by the organism.

VR Sickness

Adverse symptoms from VR usage, caused by discomfort due to problems in the VR hardware and low-level software.

Virtual World Generator (VWG)

Runs on a computer and produces "another world" for VR experiences.

Ponzo Illusion

Causes the upper line segment to appear larger than the lower one, revealing visual system shortcomings.

Degrees of Freedom (DOFs)

Rigid object movements in space, with 3 DOFs for position and 3 for rotation.

Sense Organ

Serves as a sensor converting energy into neural impulses, crucial in VR experiences.

Look-at

Description of the eye's position, central looking direction, and up direction.

Visible Light Spectrum

Range of electromagnetic waves visible to humans, important for perceiving colors.

Lenses

Prisms, convex, and concave lenses bend light rays in different ways, affecting vision in VR.

Ciliary muscles

Muscles that alter the optical power of the lens in the eye.

Fovea

The central part of the retina responsible for the highest visual acuity.

Optic disc

A small hole in the retina through which neural pulses are transmitted via the optic nerve.

Photoreceptors

Cells in the retina that capture light and convert it into neural signals.

Cones

Photoreceptor cells in the retina responsible for high acuity vision.

Rods

Photoreceptor cells in the retina used in low light conditions.

Visual pathway

The route light takes through the eye, hitting photoreceptors, passing through the optic nerve to the brain.

Binocular disparity

The difference in the images seen by each eye, providing depth perception.

Monocular vision

Vision using one eye only.

Stereo cues

Depth cues that require input from both eyes.

Motion parallax

Nearby objects appear to move faster than distant objects as the observer moves.

Optical flow

The pattern of apparent motion of objects, dependent on the observer's viewpoint.

Frame rate

The number of frames displayed per second, important for smooth motion perception.

Visibility problem

The challenge in computer graphics of determining which objects are visible in a 3D scene.

Ray tracing

A rendering technique simulating light rays to create realistic images.

Culling

The process of eliminating unnecessary objects before rendering to improve performance.

Ray casting

Calculating the intersection of viewing rays with objects in a virtual world.

Surface normal

A vector perpendicular to a surface, important for shading in rendering.

Latency

The delay between an action and its visual feedback, crucial in virtual reality experiences.

Bump mapping

Technique to create the appearance of surface roughness in computer graphics.

Degrees of freedom (DOF)

The number of independent parameters needed to describe the position of a rigid body in space.

Gyroscope

Device measuring angular velocity along three orthogonal axes.

Vestibular system

Organs in the inner ear that sense head motion and acceleration.

Semicircular canals

Structures in the inner ear that measure angular acceleration.

Cupula

A flexible structure in the semicircular canals that contains hair cells and blocks a small section of the canal.

Vestibulo-ocular reflex (VOR)

A reflex that stabilizes images on the retina during head movement by coordinating eye movements.

Vection

Visually induced sensation of self-motion, playing a role in VR sickness.

Inside-out tracking

Tracking system where sensors are placed on the headset.

Outside-in tracking

Tracking system where sensors (like IR cameras) are located outside the headset.

Sensor fusion

Process of combining information from multiple sensors to improve tracking accuracy.

Redirected walking

Technique in VR where users are made to think they are walking in straight lines while walking in circles.

Teleportation

Technique in VR where users are instantly transported to another location.

Hand tracking

Interaction technique in VR that tracks hand movements without controllers.

Voice interaction

Interaction technique in VR where users can interact using voice commands.

Hair cells

Cells in the inner ear that transduce sound vibrations into neural impulses.

Cone of confusion

Geometrically defined area where sounds from different locations produce the same interaural time difference and interaural level difference.

Binaural auditory cues

Auditory cues that rely on differences in sound arrival time and intensity at the two ears for localization.

Interaural time difference (ITD)

Sounds arriving at the two ears at different times.

Interaural loudness difference (ILD)

Difference in loudness at the two ears, often due to acoustic shadowing.

Auditory Virtual World Generator (VWG)

Provides information on surface location and reflectance, emphasizing low spatial and high temporal details.

VR Sickness Symptoms

Nausea, dizziness, drowsiness.

Psychophysics

Measurement of psychological or physical responses to stimuli.

Psychometric function

Mathematical tool in psychophysics modeling the relationship between a physical stimulus and a subject's response.

Maximum Likelihood Model of Cue Integration Predictions

Optimal estimate is a weighted linear combination of cues based on their reliabilities, resulting in a less variable combined estimate.

Brain-Machine Interface

Connects humans and animals to mechanical systems and VR experiences through their thoughts.

Haptic, Tactile, Proprioceptive, Somatosensory Sensations

Different types of sensory information related to touch, muscle tension, and skin sensations.