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SightLab Glossary

  • Avatar
    A 3D representation of the participant’s head and hands within the environment

  • Biopac
    A hardware and software system for physiological data acquisition (e.g., ECG, EEG). SightLab can send event markers (trial starts, fixation onsets, etc.) to Biopac for synchronized data collection.

  • Cartesian Coordinate System
    The 3D space in which SightLab operates:

  • X: right

  • Y: up

  • Z: out of the screen (toward the viewer)
    Units are in meters, relative to the environment’s origin.

  • Dwell Time
    The total time the gaze remains on an object or within an ROI before moving away. Often used as a metric of interest or engagement.

  • Environment
    The 3D world or 360° media loaded for each trial (e.g., an OSGB scene or a 360° video). Set via sightlab.setEnvironment(env).

  • Euler Angles
    Rotational orientation of objects or the user’s view, expressed as three angles (pitch, yaw, roll) in degrees.

  • Fade Quad
    A fullscreen quad used to smoothly fade the view in or out between trials (controlled by the fadequad attribute).

  • Field of View (FOV)
    The angular extent of the visible world, settable via Vizard’s window FOV parameter (default ≈79° in SightLab’s settings).

  • Fixation
    A period during which the user’s gaze remains within a small spatial threshold for at least a minimum duration (commonly ~100–200 ms), indicating a moment of visual attention; recorded in trial data via a fixation status flag

  • GAZE_TIME_EVENT / GAZE_END_EVENT
    Built-in SightLab callback events:

  • GAZE_TIME_EVENT fires when gaze on an object exceeds the dwell threshold.

  • GAZE_END_EVENT fires when gaze leaves an object after a fixation/dwell.

  • Gaze Path
    The trajectory of consecutive gaze points over time, showing where the user looked throughout a trial. Can be visualized as a line or “path” in replay.

  • Gaze Point
    The 3D intersection point where the combined eye gaze ray meets a scene object. SightLab computes this each frame and can display it as a small sphere in the mirrored view.

  • Grab Event
    Triggered when the participant “grabs” an object marked with grab=True (e.g., using a controller button). Useful for interaction studies.

  • Headlight
    A directional light attached to the user’s viewpoint to illuminate the scene automatically. Toggle via sl.SightLab(headlight=True).

  • Heat Map
    A visualization overlay that color-codes areas of the scene by gaze density (how often or how long they were looked at), helping identify hotspots of visual attention.

  • HUD (Heads-Up Display)
    On-screen display showing trial time, participant ID, or instructions. Accessible via sightlab.hud for getting current time or updating text.

  • Inspector
    A versatile visual browser and editor for 3D models in SightLab and Vizard Inspector allows users to view and manage scene graph nodes, add or edit objects, tag ROIs, adjust lighting and starting points and more

  • Node / Scene Graph
    Vizard’s hierarchical structure of transform and group nodes. SightLab leverages this to manage ROIs, custom objects, avatars, etc.

  • Participant ID (PID)
    A unique identifier you can enable (via pid=True) so that data files are labeled per participant.

  • Replay Mode
    After data collection, SightLab can replay trials showing gaze paths, heat maps, dwell/fixation spheres, and avatar positions using the replay.py GUI.

  • ROI (Region of Interest)
    A user-defined 3D area or object tag in the scene where gaze data (dwell time, fixations, etc.) is specifically recorded and analyzed. ROIs are typically created by adding a RegionOfInterest.osgb node in the Inspector and tagging it for data collection.

  • Scene Object
    Any Vizard node you add to SightLab for tracking or interaction. For example:
    ```python sightlab.addSceneObject('Cube', cubeNode, gaze=True, grab=True)

  • Saccade
    A rapid eye movement between fixations. Saccades are characterized by high velocity and short duration, used to reposition the gaze to new areas of interest.

  • Time to First Fixation
    The latency from trial start to the moment of the first fixation on any ROI or scene object. A measure of initial attention allocation.

  • Trial
    One repetition or segment in your experiment. A trial begins with sightlab.startTrial() (optionally showing instructions) and ends with sightlab.endTrial(). You control trial count via sightlab.setTrialCount().

  • Vizard
    A Python-based VR development platform by WorldViz. It serves as the underlying engine for SightLab, providing scene graph management, rendering, input handling, and interaction capabilities.