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Viewing Editing Gaze Positions

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candytaco edited this page Apr 6, 2021 · 4 revisions

SharpEyes offers a feature to view the gaze location overlaid on the stimulus frames, and the ability to manually edit those locations if they are off.

General usage

  1. From the main SharpEyes windows, to go Tools->Stimulus View to open the stimulus view window.
  2. Load the stimulus video in the Stimulus Viewer (File->Load Video, or the Open Video button in the toolbar)
  3. Load the gaze positions (which had been stored as a numpy array) (File->Load gaze or the Load Gaze button)
  4. (optional) if needed, set the "eyetracking FPS" value in the right-hand controls panel. Most eyetracking data are at 60 fps, and this is the default value.
  5. Find/Set the time at which the gaze position data starts. The gaze data never starts at the same time as the screencap, so we need to find the time in the stimulus video that the eyetracking starts. All gaze data has been trimmed to start at the beginning of the fMRI data runs.
    • In the driving screencaps, the fMRI data starts are burned into the video. Press the "Auto find data start" button, and SharpEyes will automatically try to find the data start.
    • Check that the start it found is correct. In the driving experiment, the fMRI data starts at the frame right before the screen turns to a flat gray. If SharpEyes did not find the correct frame, you will need to manually set it.
    • You can scrub through the video using either the buttons below the video, or using the scroll wheel. one notch on the wheel scrubs one frame. Once you have found the right frame, click "Set current as data start." The Keyframes box should be populated with three entries that correspond to:
      • the start time of the gaze data
      • the end of the eyetracking calibration time in the driving video (only meaningful if working with driving data)
      • the end time of the gaze data
  6. Play through the video to watch the gaze.
    • For the driving data, check that you have set the gaze data timing correctly by watching the gaze position during the calibration sequence. It should follow the dot around the screen.
  7. To edit the gaze position, pause the video and click "Move gaze" to enter gaze editing mode. Click and drag the gaze position.
    • Every time you edit a gaze, that frame becomes a keyframe and is added to the list in the controls panel.
    • The delta you apply to the position in that frame is applied to every successive frame.
    • The delta is also retroactively applied to all frames between the current frame and the previous keyframe, and is interpolate to 0 at the previous keyframe.
  8. TO save the gaze, use File -> Save Gaze (or Save gaze as)

Controls

Space : play/pause video

Mouse scroll : scrub individual frames

❮❮/❯❯ : Go to previous/next keyframe

⮜/⮞ : Scrub individual frames.

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