# Acronyms and Vocabulary

## Acronyms

| Term | Expanded | In this course |
|---|---|---|
| AR | Augmented Reality | Digital visuals/objects augment a view of the physical world. |
| API | Application Programming Interface | A defined way for software frameworks/components to exchange capabilities or data. |
| AVP | Apple Vision Pro | Apple's spatial-computing headset. |
| FoV | Field of View | The portion of the scene visible at one time. |
| GDD | Game Design Document | Documents a game's intended actions, mechanics, flow, and production components. |
| HCI | Human-Computer Interaction | Study/design of how people interact with computer systems. |
| HUD | Heads-Up Display | Information overlaid in the user's forward view, e.g. a vehicle/pilot display. |
| IoT | Internet of Things | Connected physical devices that sense, exchange data, or personalize behavior. |
| LiDAR | Light Detection and Ranging | Sensing technology that estimates distance/3D structure using light. |
| ML | Machine Learning | Methods that let systems infer patterns from data; can support environment/activity sensing. |
| MR | Mixed Reality | Spatial digital content is situated in and can respond to the physical environment. |
| PBR | Physically Based Rendering | Material/shading approach that models how surfaces respond to light. |
| SLAM | Simultaneous Localization and Mapping | Build a map while estimating the system's position within it. |
| UI | User Interface | Controls and presentation through which the user interacts. |
| UX | User Experience | The broader end-to-end experience of a product or service. |
| VPS | Visual Positioning System | Uses visual/location data to position content accurately in a real place. |
| VR | Virtual Reality | Primarily virtual environment that replaces the user's view of the physical world. |
| WebXR | Web-based XR | Browser technologies/APIs for XR experiences. |
| XR | Extended Reality | Umbrella term for AR, VR, MR, and related spatial experiences. |
| USDZ | Universal Scene Description (zip-compressed) | 3D object format used for AR assets; can carry materials and animation. |
| glTF | Graphics Language Transmission Format | Open 3D asset format used for AR objects, materials, and animation. |

## Vocabulary

| Term | Plain-language meaning |
|---|---|
| Absolute scale | A digital object is represented at its intended real-world size. |
| Affordance | What an object or control can let a user do. |
| Anchor / target | A real-world reference used to place or track AR content. |
| Ambient/passive input | Context sensed without a direct command, such as environment/activity data. |
| Anticipation | The stage that sets expectations and motivates entry into an experience. |
| Avatar | A digital representation of a person; may be stylized or realistic. |
| Bounded volume | A defined 3D region for spatial content/apps. |
| Collider | A boundary used to detect contact; real-world colliders let physical objects affect AR interactions. |
| Competence | Reward from learning, mastery, progress, or effectiveness. |
| Core loop | Repeatable action-feedback-reward cycle, typically within the Doing stage. |
| Gaze | Eye direction used to target/select spatial content. |
| Occlusion | Correct visual blocking between real and virtual objects. |
| Optical see-through | Direct view of the physical world through transparent lenses, with digital imagery added. |
| Pass-through | Camera-captured view of the physical world shown on headset displays. |
| Persistence | AR content remains tied to a place/object over time or across users. |
| Persona (spatial avatar) | Realistic digital likeness intended to preserve recognizable face-to-face presence. |
| Reciprocity | Reward from mutual exchange or contributing value to others/a community. |
| Relatedness | Reward from social connection, belonging, or shared activity. |
| Screen space | UI/content fixed to the 2D display plane. |
| Signifier | A cue that communicates how or where to act (e.g. highlight, label, arrow). |
| Spatial audio | Sound positioned/directed in relation to a virtual object or scene. |
| Spatial object | An object with position, scale, and orientation in 3D space—even if it looks flat. |
| Trigger | An input/condition that starts an event or behavior. |
| World space | 3D content positioned relative to the surrounding environment. |