Augmented/ Virtual Reality Final

Roll (x), Pitch (y), and Yaw (z)

The three types of rotations.

Augmented Reality

a general term applied to a variety of display technologies capable of overlaying or combining alphanumeric, symbolic, or graphical information with a user’s view of the real world.

Reflector or Reflex Sight

An invention of Sir Howard Grubb, using a series of optical elements to overlay a targeting reticle, focused at optical infinity, on a distant target.

Heads-Up Display

a transparent display mounted in front of the pilot that enables viewing with the head positioned “up” and looking forward, instead of angled down, looking at instruments lower in the cockpit

projector unit, combiner, and video generation computer

Components of a Heads-Up Display

Blackburn Buccaneer

The first aircraft to employ an HMD.

Optical See-Through

An AR device which overlays information on the user’s real world view.

Video See-Through

An AR device which overlays information on a video feed of the world in front of the user.

Virtual Reality

display technologies, both worn and fixed placement, that provide the user a highly compelling visual sensation of presence, or immersion, within a 3D computer model or simulation

Telesphere Mask

The first Head-Mounted display.

Sensorama by Morton Heilig

An arcade-style theatre cabinet designed to stimulate all human senses

Sword of Damocles

The first VR/ AR HMD to be connected to a computer and not a camera.

Physical space

A boundless, three-dimensional extent within which objects and events occur and have relative position and direction

Visual space

the perceived space, or visual scene, of the virtual environment being experienced by a user or participant.

Virtual object space

An area in which the location and shape of entities in the 3D model can be precisely defined using one of multiple coordinate systems and simple geometry

Cartesian Coordinates

A system in which each point is uniquely specified using three numerical coordinates (x,y,z) representing specific distances (measured in the same unit of length) from three mutually perpendicular planes.

6 DOF

X, Y, Z, Roll, Pitch, and Yaw

Euler Angles

A movement system based on combinations of single rotations by a given angle about a fixed axis, although gimbal lock and jerky motion become issues

Quaternions

A normalized 4-coordinate system that provides a way to interpolate smoothly between orientations in space and is faster than combining rotations expressed in matrix form.

Cornea

a transparent, dome-shaped structure, the surface which is composed of highly organized cells and proteins.

Pupil

a hole located in the center of the iris, which allows the light to strike the retina

Crystalline Lens

an almost perfectly transparent, flexible structure and is composed of concentrically arranged shells of fiber cells

Accommodation

The variable process by which the optical power of the eye is changed to allow an observer to rapidly switch focus between objects at different depths of field

Retina

a multilayered sensory tissue that covers about 65  percent of its interior surface of the eye and serves a similar function as the film in a camera

Pigment Epithelium

the outermost, deepest layer of the retina

Isomerization

A chemical reaction which causes changes in the electrical properties of the photoreceptors and the release of neurotransmitters, causing impulses to be passed on.

Iodopsin and Rhodopsin

The two chemicals involved in isomerization

1. Cones, 2. Rods

most 1. are concentrated in the fovea, while 2. are absent there but dense elsewhere.

Fovea

The center of the retina, to where the eye focuses light.

Vergence

which is the pointing of the fovea of both eyes at an object in the near field. The only process in which the eyes move in opposite directions.

Stereopsis

The primary depth cue for binocular vision, with each eye capturing the scene from a slightly different angle

Motion Paralax

a strong, relative motion cue within which objects that are closer to a moving observer appear themselves to move faster than objects that are farther away

Occlusion

when one object blocks an observer’s view of another object

Deletion and Accretion

The two parts of occlusion.

Linear Perspective

the monocular depth cue provided by the convergence of lines toward a single point in the distance

Kinetic Depth Effect

perception of an object’s complex, 3D structure from that object’s motion

Familiar Size

if we know how large an object is at a distant location, our brain can use that understanding to estimate absolute distances

Relative Size

If two objects are similar in size but offset in terms of their distances from the position of the observer, we perceive the one that casts a smaller image on the retina as being farther away, and the one with the larger image as being closer.

Aerial Perspective

the effect of light being scattered by particles in the atmosphere, such as water vapor and smoke between an observer and a distant object or scene.

Texture gradient

a strong depth cue within which there is a gradual change in the appearance of textures and patterns of objects from coarse to fine (or less distinct) as distance from the observer increases.

Perspective Gradient

An aspect of texture gradient. Separation of texture elements perpendicular to the surface slant or angle of viewing appears to decrease with distance

Compression gradient

An aspect of texture gradient. The apparent height of texture elements decreases with increasing distance.

Density gradient

An aspect of texture gradient. Density, or number of elements per unit area, increases with increasing distance.

Optical Expansion

allows an observer to perceive an object as moving, and the distance of the object as well

Relative Height

Objects shorter than your eye will appear lower in your vision, and objects taller than your eye appear higher.

LCD (liquid crystal display)

an electronically modulated transmissive display device composed of two sheets of polarizing material, the axes of which are aligned perpendicular to each other. Between the polarizing sheets is an array of cells arranged in rows and columns containing liquid crystal molecules.

OLED

a solid-state display technology based on organic (carbon and hydrogen bonded) materials that will emit light when electric current is applied (electroluminescence)

DLP or DMD

a class of micro-electro-mechanical systems (MEMS) known as spatial light modulators. On the surface of this chip is an array of up to two million individually controlled micromirrors, each of which can be used to represent a single pixel in a projected image

LCoS

a cross between LCD and DLP technologies. Constructed on a silicon wafer overlaid with a highly reflective coating, it uses nematic or ferroelectric liquid crystal to modulate field sequential colored light reflected off this backplane.

Lumen

the unit of measure for quantifying luminous flux

Luminous flux

quantitative expression of light energy per unit of time radiated from a source over wavelengths to which the human eye is sensitive

Luminous intensity

the luminous flux per solid angle emitted or reflected from a point.

Candela

the unit of measure for quantifying luminous power per unit solid angle emitted by a point light source in a particular direction. (measure of luminous intensity)

Luminance

the measure of luminous intensity per unit area projected in a given direction

Illuminance

the luminous flux incident on a surface per unit area

Brightness

a subjective attribute or property used to express the luminance of a display

Spatial resolution

the number of individual pixel elements of a display and is presented as numerical values

Pixel Pitch

the distance from the center of one pixel to the center of the next pixel

Fill Factor

the amount of black space between individual pixel elements

Persistence

the length of time a pixel remains illuminated

Latency

the elapsed time between the movement of a head-mounted display and the actual display elements updating

Response time

the measure of time a pixel takes to change

Color gamut

a specific range of colors a device is capable of producing

Contrast

the relative difference between light and dark areas of a display

Collimation, Magnification, and Relay

The three purposes of optics

Collimation

an image source appears at a distance greater than its physical distance from the wearer’s eyes

Magnification

an image appears larger than the actual source

Relay

transfer of light patterns from an image source, sometimes located off axis, to the wearer’s eyes

Field of View

the total angular size of the virtual image visible to both eyes, expressed in degrees

Binocular overlap

that part of the total visual field within which the monocular FOV for our two eyes overlap

Interpupillary Distance (IPD)

the distance between the centers of the pupils of the two eyes

Eye Relief

the distance from the cornea of the eye to the surface of the first optical element

Exit Pupil

the diameter of light transmitted to your eye by an optical system

Eye Box

the volume within which users can place their pupils and experience the full performance of the device

Frequency

the rate of movement of molecules set into motion as a result of the vibration of an object and is measured in hertz

Amplitude

the measurement of the maximum displacement of air molecules in a sound wave

Echo

a separated reflection of sound

Reverberation

reflected waves combine with the original sound waves to form what is perceived to be a single, elongated sound

Diffraction

a change in direction of waves as they pass through an opening or interact with a barrier in their path

Refraction

a change in the direction of waves as they pass between mediums

Pinna

the external portion of our ear

Eardrum

a thin, semi-transparent, oval-shaped membrane approximately 10 mm in diameter

Mallus, Incus, and Stapes

3 bones which carry out transduction

Cochlea

a spiral-shaped cavity in the temporal bone making 2.75 turns around its axis

Oval and Round Window

Small membranes which compensate for the movement of air in the inner ear

Organ of Corti

composed of four rows of hair cells, it detects pressure

The Auditory Nerve

responsible for transferring electrical signals from hair cells in the Organ of Corti to the auditory centers of the brain for processing

Binaural

of, relating to, or involving two ears

Interaural Time Difference

the difference in the arrival time of a sound between the two ears

Interaural Intensity Difference

the difference in the intensity of a sound between the two ears

Monoaural Sound

a basic sound reproduction format within which all audio signals are combined into a single channel and fed to a single speaker

Stereo Sound

an audio recording or reproduction format within which multiple audio signals are combined into two independent audio channels.

Surround Sound

an enhanced audio system within which a semi-immersive soundscape is created using a combination of digital signal processing techniques as well as four or more independent audio channels routed to an array of speakers strategically situated around a central listening position

Binaural recording

a method of capturing a soundscape—be it in a studio, a concert hall, or in a natural outdoor setting—in a manner similar to the way in which a healthy individual actually hears one’s real-world surroundings

WAV and AIFF

Uncompressed file formats best for AR and VR audio applications

X and Z

The coordinates used for VR audio

Protection, Regulation, and Sensation

Functions of the skin

Epidermis

The top layer of the skin

Dermis

The middle layer of the skin.

Hypodermis

The deepest layer of the skin.