Immersion
A psychological perception of being physically present in a virtual environment. This concept is in contrast to the metaphor of a “window”, where one observes what is happening “from the outside”. In the context of Extended Reality (XR), “immersion” is the condition in which the user loses awareness of the fact that they are actually in an artificial world.
Latency
The time delay (also called lag) that occurs when there is a change in input from the experiencer and it’s accomplishment, often creating a mismatch between the motion you feel and see. In the real world, there is a virtually no latency. In virtual worlds, the average latency is 20 milliseconds, which is considered low.
Light Field
An optical technology that enables objects to be displayed at varying focal planes, allowing for the illusion of depth in an augmented reality experience.
Minimum Frame Rate
The amount of frames per second that is needed to avoid stuttering or user simulation sickness. The higher the framerate, the more realistic a virtual reality experience will feel.
The predominantly virtual spaces where real world objects or people are dynamically integrated into virtual worlds to produce new environments and visualizations where physical and digital objects co-exist and interact in real time.
The continuous scale ranging which covers all possible variations and compositions of real and virtual objects. The continuum ranges from a completely real and natural environment, to a completely virtual environment. The concept was first introduced by Paul Milgram.
Optical Engine
A component found in a head-mounted device that generates visual content for the user. Optical engines include the device’s GPU, light-generating element, and mirroring elements, all connected to a CPU and interface for input, as well as a transparent display for output.
Pitch
The rotational movement around the horizontal (x) axis.
Presence
In the context of reality technologies, is when enough of one’s senses have been stimulated to the point that the user feels, believes, and accepts that they are physically occupying a new virtual world. Achieving comfortable, sustained presence requires a combination of the proper virtual reality content and hardware.
Refresh Rate
The number of times in a second that a display hardware will update its buffer, thus, how quickly a display hardware can change its content over a particular length of time. This is different from the measure of frame rate, in that refresh rate includes the repeated drawing of identical frames, while frame rate measures how often a video source can feed an entire frame of new data to a display.
Room Scale
A design paradigm for Virtual Reality experiences that allows users to move freely within a room-sized environment, while partaking in a virtual reality (VR) experience. The experiencer’s physical movements are mirrored within the virtual world and helps to contribute to a greater sense of immersion, with the body being directly engaged.
Simulation Sickness
In the context of virtual reality, simulation sickness refers to the feeling of dizziness and nauseousness. It is different from motion sickness because it can be caused without any movement, rather by the visually-induced perception of movement. The physiology behind VR sickness is believed to be caused by slower than required refresh rate of on-screen images. This is when the refresh rate is slower than what the human brain processes, which causes a discord between the VR refresh rate and the human brain processing rate; the result is perceived glitches on the screen.
Social VR
(also called Social Virtual Reality) The gathering of participants in a simulated world using a virtual reality (VR) system and social VR app. Participants appear as avatars in shared VR spaces that can be lifelike or fantasy worlds, and users can interact with each other and even participate in activities.
Stitching
The process of taking footage from different cameras, such as GoPro cameras that have been used in a 360 camera mount, and combining that footage into spherical video. The process usually involves reorienting video, placing seams, and generally editing it so that it looks like one continuous view, rather than a patchwork of angles.
Tracking
The method in which a computer understands a user’s movements and then acts upon them accordingly to maintain full immersion. Tracking involves computer anchored content to a fixed point in space, allowing experiencers to walk and/or look around it, as defined by the degrees of freedom allowed by the display device. There are several types of tracking in reality technologies, such as head tracking, motion tracking, eye tracking, marker-based tracking, and marker-less tracking.
A realistic simulation of an environment that is created with a mixture of interactive hardware and software, and presented to the user in such a way that the user suspends belief and accepts it as a real environment.
Virtual Reality (VR) Glasses
See “Head-Mounted Display (HMD)”
Virtual Reality (VR) Headset
See “Head-Mounted Display (HMD)”
Virtual Reality (VR) Sickness
See “Simulation Sickness”
Virtual World
A three dimensional environment, often (but not necessarily) realized through a medium (rendering pipeline, display, etc.), where one can interact with others and create objects as part of that interaction.
WebVR
An emerging reality technology that aims to present virtual reality content in traditional web browsing interfaces. WebVR experiences are delivered through a JavaScript API that provides support for virtual reality devices.
Yaw
The rotational movement around the around the vertical (y) axis.
