Glossary

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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…

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