Surface Tracker ​

You can use this plugin to detect markers in the recording, define surfaces, edit surfaces, and create and export visualizations of gaze data within the defined surfaces.

Setup ​

Ensure that your recording contains AprilTag Markers, like the ones you would use with the Marker Mapper.

Workflow ​

Here is an example workflow for using the Surface Tracker plugin to generate heatmap visualizations and export surface data reports:

• Load the Surface Tracker plugin - if you already have surfaces defined, the load may take a few seconds because the plugin will look through the entire video and cache the detected surfaces.
• Add surface - if you do not have any defined surfaces, you can click on the Add surface button when the markers you want to user are visible or just click the circular A button in the left hand side of the screen.
• Surface name and size - in the Surface Tracker menu GUI, define the surface name and real world size.

Export Format ​

Results exported to the subfolder surfaces. The different reported metrics are:

• surface_visibility.csv - Overview of how many world camera frames each surface was contained in.
• surface_gaze_distribution.csv - Overview of how many gaze samples have been collected on each individual surface and outside of surfaces.
• surface_events.csv - List of image-enter and image-exit events for all surfaces.

Further the following metrics are reported for every individual surface. Each surface has a name, which can be manually set as described above. This name is augmented by an automatically generated numerical identifier.

• gaze_positions_on_surface_<surface_name>.csv - A list of gaze datums on the surface. x_norm and y_norm are coordinates between 0 and 1, where (0,0) is the top left corner of the surface and (1,1) is the bottom right corner.
• fixations_on_surface_<surface_name>.csv - A list of fixations on the surface. The values include fixation locations as normalized coordinates and a confidence value between 0.0 and 1.0, indicating gaze on/off surface.
• surf_positions_<surface_name> - List of surface positions in 3D. The position is given as the 3D pose of the surface in relation to the current position of the scene camera. img_to_surf_trans is a matrix transforming coordinates from the camera coordinate system to the surface coordinate system. surf_to_img_trans is the inverse of img_to_surf_trans.

Additionally, the Surface Tracker exports the detected markers to the marker_detections.csv file. The world_index column represents the scene video frame index, marker_uid is the label used for identifying a single marker, and corner_<0|1|2|3>_<x|y> is the corner coordinate in pixel space.