Glossary

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Landmark-Based Navigation(also: Landmark Navigation, Landmark-Based Wayfinding)

A wayfinding strategy that uses recognisable environmental features such as buildings, signs, or other prominent objects as reference points for giving directions, rather than relying solely on street names or turn-by-turn instructions. Research has shown that landmark-based…

Landmarks(also: ARIA Landmarks, Page Landmarks, Landmark Regions)

Designated regions of a web page that provide structural navigation points for assistive technology users. ARIA landmark roles include banner, navigation, main, complementary, contentinfo, search, form, and region. Screen reader users can jump between landmarks using keyboard…

Last Meter Problem(also: Last Mile Problem, Final Approach Problem)

In assistive technology for blind users, the challenge of bridging the gap between knowing an object exists and physically reaching or interacting with it. While object detection apps can identify what objects are present and approximately where they are, they typically cannot…

Last-Few-Meters Problem(also: Last 10 Meters Problem, Last Mile Problem (Navigation))

The navigation challenge that occurs when GPS or other positioning systems bring a person with a visual impairment to the general vicinity of their destination (typically within 5-10 meters) but cannot guide them to the precise location, such as a specific entrance, storefront,…

Last-Few-Metres Problem(also: Last Few Meters Problem)

The difficulty that blind and low-vision pedestrians face in the final short distance (roughly the last several metres) of a trip, where GPS accuracy degrades, building entrances are ambiguous, and digital navigation apps leave users in the general vicinity of a destination…

Last-few-meters Wayfinding(also: Last-meter wayfinding, Last-few-meters problem)

The final segment of an indoor or outdoor journey, from the nearest routable point (a building lobby, a doorway, a kerbside pin on a map) to the exact end destination (a specific room, counter, or seat). For blind travellers, this last segment is disproportionately difficult:…

LiDAR(also: Light detection and ranging, Laser scanning)

A remote sensing technology that measures distances by emitting laser pulses and analysing the reflected light, producing precise three-dimensional point clouds of the surrounding environment. In accessibility, LiDAR has multiple applications: it is used to assess pedestrian…

Line Standing(also: Queueing, Standing in line, Line navigation)

The everyday social activity of waiting in an ordered queue — at a cashier, bus stop, check-in counter, or reception desk. For blind people, line standing is an often-overlooked accessibility challenge: the end of the line is a dynamically moving position that cannot be located…

Link Annotation(also: Link Augmentation, Link Labelling)

The practice of adding supplementary information to hyperlinks to help users make informed navigation decisions before clicking. In web accessibility, link annotations may include the accessibility level of the target page, the file type and size of linked documents, or…

Local Navigation(also: Local guidance, Fine-grained navigation)

Navigation at the scale of a few metres, where the task is to bring a blind traveller into direct body-scale interaction with a specific landmark object — sitting in a particular chair, pressing an elevator button, reaching a door handle, boarding through a specific train door.…

Localization(also: Position Estimation, Indoor Localization, User Localization)

Localization is the process of determining a user's position within an environment, typically using a combination of sensors such as GPS, inertial measurement units, BLE beacons, Wi-Fi signals, or computer vision. Accurate localization is the foundational challenge for all…

Location Awareness(also: Location-Aware Computing, Location Sensing)

The ability of a computing system to determine and respond to the physical location of a user or device, typically using GPS, Wi-Fi positioning, cellular triangulation, or other sensing technologies. In assistive technology, location awareness enables context-sensitive support…

Location-Based Service(also: LBS, Location-Based Services)

A software application or platform that uses geographic position data — from GPS, Wi-Fi, Bluetooth beacons, or other localization technologies — to deliver context-aware information or functionality to users based on their physical location. In accessibility, location-based…

Macro-Navigation(also: Macro Navigation)

The process of navigating through the broader environment at the level of routes, streets, landmarks, and destinations — knowing where you are in a city, which direction to travel, and how to reach a distant goal. In contrast to micro-navigation (detecting immediate obstacles…

Map Accessibility(also: Accessible maps)

The practice and field of making maps — digital geovisualizations, online navigation maps, tactile maps, and physical signage — perceivable, operable, understandable, and robust for users with disabilities. Map accessibility spans multiple modalities: tactile maps with raised…

Mental Map(also: Cognitive Map, Mental Model of Space)

An internal cognitive representation of a physical environment, including spatial relationships, landmarks, routes, and distances. For people with blindness or visual impairments, building a mental map of a route before traveling is a critical strategy for independent mobility,…

Micro-Navigation(also: Micro Navigation)

The process of navigating the immediate environment — detecting and avoiding obstacles, following the edge of a pavement, identifying surface changes, and maintaining a safe path. For blind and visually impaired travellers, micro-navigation is the domain of traditional primary…

Microsoft Soundscape(also: Soundscape)

Microsoft Soundscape was an accessible navigation app developed by Microsoft Research that used spatialized 3D audio to help blind and low-vision users build awareness of their surroundings. Rather than providing turn-by-turn directions, Soundscape placed virtual audio beacons…

NFC Tag(also: Near Field Communication Tag, NFC)

An NFC (Near Field Communication) tag is a small, unpowered chip that can transmit data to a compatible smartphone or device when held within a few centimeters. In accessibility contexts, NFC tags are used in museums, galleries, and public spaces to provide on-demand information…

NavCog(also: Navigational Cognitive Assistant)

A Bluetooth beacon-based navigation system developed at Carnegie Mellon University that provides indoor turn-by-turn navigation assistance and environmental information to blind and visually impaired users via smartphone. NavCog works by detecting BLE (Bluetooth Low Energy)…

Navigation

The task of moving through an environment to reach a destination, encompassing route planning, mode selection, real-time decision-making, and responding to obstacles. In accessibility research, navigation is often paired with wayfinding (the embodied, situated practice of…

Navigation Axis(also: Multi-Axial Navigation, Axis-Based Navigation)

A navigation axis is a concept from screen reader research describing a specific linear serialization of a subset of web page elements that represents one navigation strategy. Rather than forcing blind users through a single reading order (the DOM order), a multi-axial…

Non-Visual Exploration(also: Non-Visual Interaction, Non-Visual Scanning)

The process by which blind or visually impaired people gather information about their physical environment, documents, or interfaces without relying on sight. Non-visual exploration combines multiple strategies including touch, audio feedback, spatial memory, contextual…

Obstacle Avoidance(also: Obstacle Detection)

The ability to detect and navigate around physical barriers in one's path, a critical mobility skill for blind and visually impaired people. Traditional obstacle avoidance relies on long cane techniques (sweeping the cane side to side to detect ground-level hazards) and guide…

Obstacle Detection(also: Obstacle Avoidance)

Technology or techniques that identify physical barriers in a person's path and alert them in time to take corrective action. For people who are blind or visually impaired, obstacle detection systems use sensors (ultrasonic, infrared, LiDAR, or camera-based) embedded in devices…

Occupancy Grid Map(also: 2D occupancy grid, Grid map)

A representation of an environment as a grid of cells, where each cell is labelled as walkable (free space), non-walkable (obstacle or wall), or unknown. Occupancy grid maps are a standard data structure in robotics and are increasingly used in blind-navigation systems built on…

OpenStreetMap(also: OSM)

A free, collaborative, open-source mapping project that provides geographic data including roads, buildings, and points of interest, contributed and maintained by volunteers worldwide. OpenStreetMap is significant for accessibility because its open data can be freely used to…

Over-rotation(also: Rotation overshoot, Turn overshoot)

The phenomenon where a person rotates beyond a target heading angle when following a turn instruction, typically caused by the delay between perceiving a stop signal and physically halting the rotation. In navigation assistance for blind users, over-rotation is a systematic…

Palm Drawing(also: Palm Mapping, Palm Tracing)

A technique used by Orientation and Mobility (O&M) specialists to teach routes to people who are blind or have low vision. The instructor holds the person's palm face up and traces the path of a route with their finger while simultaneously providing verbal instructions. This…

Particle Filtering(also: Sequential Monte Carlo, Particle Filter)

Particle filtering is a probabilistic localization technique that estimates a user's position by maintaining a cloud of weighted "particles," each representing a possible location. As new sensor data arrives—from GPS, inertial sensors, or other sources—particles are updated,…

Particle filter(also: Sequential Monte Carlo, Monte Carlo localization)

A probabilistic algorithm that estimates a user's position by maintaining a set of weighted hypothetical locations (particles) and updating them based on sensor observations such as Bluetooth beacon signal strengths. In indoor navigation for people with visual impairments,…

Passive Accessibility Sensing(also: Automatic Barrier Detection, Breadcrumb Sensing)

A data collection approach that uses smartphone sensors (GPS, accelerometers, gyroscopes) to automatically detect potential accessibility barriers in the physical environment without requiring active user input. By analysing patterns in pedestrian movement data — such as…

Passive notification(also: Automatic notification, Push notification)

Information delivered to a user automatically without requiring active input, triggered by context such as location, time, or system state. In assistive navigation for people with visual impairments, passive notifications are preferred because users' hands and attention are…

Path Integration

A cognitive navigation process in which a person tracks their position relative to a starting point by continuously monitoring their movements — including direction changes, distance traveled, and turns taken. People who are blind rely heavily on path integration when navigating…

Pedestrian Dead Reckoning(also: PDR, Inertial Navigation)

A localization technique that estimates a pedestrian's position by tracking their movement from a known starting point using inertial sensors (accelerometers and gyroscopes) found in smartphones. The accelerometer detects individual steps through peak detection, while the…

Pedestrian Navigation System(also: Pedestrian GPS, Walking Navigation)

A navigation system designed specifically for people travelling on foot, as opposed to systems designed for car drivers. Pedestrian navigation systems must account for footpaths, crosswalks, stairs, pedestrian bridges, and indoor routes that vehicle-focused systems typically…

Pedestrian dead reckoning(also: PDR, Inertial navigation, Step-and-heading)

A localization technique that estimates a person's position by counting their steps (to determine distance) and detecting turns (to determine heading changes) from a known starting point, using inertial sensors in a smartphone or wearable device. For blind indoor navigation,…

Physical Crowdsourcing(also: Spatial Crowdsourcing, Physical World Crowdsourcing)

A form of crowdsourcing in which tasks require participants to perform actions in the physical world rather than completing digital tasks online. In an accessibility context, physical crowdsourcing has been applied to installing and maintaining navigation infrastructure such as…

Point of Interest(also: POI)

A point of interest (POI) is a specific location or feature in a physical environment that is relevant to a user's navigation or understanding of their surroundings. In accessible wayfinding systems for blind and low-vision users, POIs include landmarks, obstacles, entrances,…

Points of interest(also: POI, Landmarks)

Specific locations in the environment that are useful or relevant to a user, such as shops, restaurants, transit stops, public buildings, and other named places. In accessible navigation for people with visual impairments, points of interest serve dual roles: they provide…

Proximity Detection(also: Proximity Sensing, Proximity-Based Localization)

A method of determining a user's approximate location by measuring their closeness to known reference points, such as BLE beacons or Wi-Fi access points, based on signal strength. In accessible indoor navigation systems, proximity detection is used to localize users at specific…

Pseudo-Attraction Force

A haptic illusion technique that creates the sensation of being pulled or pushed in a specific direction by exploiting the nonlinear relationship between physical and perceived acceleration. The technique uses asymmetric oscillation: a strong, brief acceleration in the intended…

Pull Notification(also: On-Demand Notification, User-Initiated Notification)

A notification or information delivery model where content is provided only when explicitly requested by the user, in contrast to push notifications which are delivered automatically. In assistive navigation contexts, pull notifications allow blind users to request specific…

RSSI(also: Received Signal Strength Indicator, Received Signal Strength Index)

A measurement of the power level of a radio signal received by a device, commonly used in Bluetooth and Wi-Fi based indoor positioning systems. In accessible indoor navigation, RSSI readings from BLE beacons are used to estimate a user's distance from each beacon — stronger…

Robotic Guide Dog(also: Robot Guide Dog, Quadruped Guide Robot)

A mobile robot — typically a quadruped platform — designed to provide navigation and obstacle-avoidance support for blind and low-vision users, filling a role analogous to that of a trained guide dog. Research prototypes have explored handler interaction, leash-based coupling,…

Route Planning(also: Journey Planning, Pre-Journey Planning)

The process of determining a path from an origin to a destination before travel begins, including selecting roads or paths, identifying landmarks and decision points, and considering factors such as safety, accessibility, and personal preferences. For blind and visually impaired…

Semantic Taxonomy(also: Environmental Semantic Taxonomy)

A structured classification system that organizes and labels environmental features and attributes using standardized vocabulary, enabling consistent description and retrieval of information about physical spaces. In accessible navigation, semantic taxonomies define the…

Semantic feature(also: Environmental feature, Landmark annotation)

A meaningful environmental attribute associated with a specific location in a navigation system, such as a doorway, floor surface change, point of interest, or tactile ground indicator. In accessible indoor navigation, semantic features serve a dual purpose: confirming the…

Shared Movement(also: Linked Locomotion, Guided Movement)

A virtual reality interaction technique that allows one user to move through a virtual environment by attaching to or following another user's avatar, inspired by the physical sighted guide technique used by blind and low vision people. In shared movement, a user can grab a…

Shorelining(also: Trailing)

An orientation and mobility technique in which a person with a visual impairment follows a consistent surface edge — such as a wall, curb, edge of a sidewalk, or other contrasting surface — to maintain a specific orientation and navigate through an environment. The technique…