Pupil LSL Relay Plugin

Plugin for Pupil Capture that publishes realtime gaze data using the lab streaming layer framework.

Installation

user plugin directory

Install pylsl
Copy or symlink pylsl with all its content to the plugin directory.
Copy pupil_lsl_relay.py to the plugin directory.

Usage

Start Pupil Capture.
Open the Pupil LSL Relay plugin.
Now the LSL outlet is ready to provide data to other inlets in the network.

LSL Outlet

The plugin opens a single outlet named pupil_capture that follows the Gaze Meta Data format.

See our pupil-helpers for examples on how to record and visualize the published data.

The published LSL data is simply a flattened version (see extract_*() functions in pupil_lsl_relay.py) of the original Pupil gaze data stream. The stream's channels will be filled with best effort, i.e. if there is a monocular gaze datum the values for the opposite eye will be set to NaN. The actual pairing of pupil data to binocular gaze data happens in Capture and is not a LSL specific behaviour. Therefore, it is possible to apply the same flattening code to offline calibrated gaze data and reproduce the stream published by the LSL outlet.

Data Format

'confidence': Normalized (0-1) confidence.

'norm_pos_x', 'norm_pos_y': Normalized (0-1) coordinates on the screen.

'gaze_point_3d_x', 'gaze_point_3d_y', 'gaze_point_3d_z': World coordinates in mm

'eye_centerright_3d_x' ... (for right/left eyes, for x/y/z): Position of eye center in world coordinates in mm.

'gaze_normalright_x' (right/left, x/y/z): End point of vector from eye center (I think).

'diameterright_2d' (right/left): Pupil diameter in pixels

'diameterright_3d' (right/left): Pupil diameter in mm

LSL Clock Synchronization

The Pupil LSL Relay plugin adjusts Capture's timebase to synchronize Capture's own clock with the pylsl.local_clock(). This allows the recording of native Capture timestamps and removes the necessity of manually synchronize timestamps after the effect.