Tobii Glasses Analysis Software – Qualitative Analysis

1. Observing behavior and Logging Events (Coding)

Tools for logging interesting and important events in the recordings are included in the software. These Custom Events, for example, “Participant picks up item 1”, can also be exported together with all the other data collected during a recording. The logged events appear on the timeline and in the Events List in the Tools panel on the right. To manually log events, you must first define a Custom Events scheme, that contains the events you want to log and define which keyboard keys you want to use for logging the events.

Define a Custom Events logging scheme:

  1. Make sure a Replay tab is active.
  2. Locate Events in the Tools panel on the right.
  3. Click the New Event Type button at the top right of the panel. The New event dialog box opens.
  4. Enter the name/description of the event in the New Event dialog box.
  5. Click the drop-down menu in the New Event dialog box and select the keyboard key or
    combination of keys that you would like to use for logging this event. It may be easy to have opposite actions defined as e.g. P-key and CTRL + P-keys
  6. Click OK.

Edit an existing Custom Event:

  1. Locate Events in the Tools panel on the right.
  2. Place the mouse cursor over the custom event you want to edit; icons appear on the right.
  3. Click the edit icon. An Edit Custom Event dialog box opens.
  4. Edit the name or description in the Custom Event dialog box.
  5. Click the drop-down menu in the New Event dialog box and select the keyboard key, or
    combination of keys that you would like to use for logging this event.
  6. Click OK.

Delete a Custom Event from the Custom Events Scheme:

  1. Locate Events in the Tools panel on the right.
  2. Place the mouse cursor over the Custom Event you want to delete; icons appear on the right.
  3. Click the Delete icon. A Delete Custom Event dialog box opens.
  4. Click Delete event to confirm.

To manually log events, you must first define a Custom Events scheme that contains the events you
want to log (see the section above).

Manually log an event:

  1. Make sure the correct Replay tab is active.
  2. Make sure you have defined the Custom Events that you would like to log.
  3. While replaying or pausing a recording press the shortcut key on your keyboard associated with the event you want to log. Alternatively, click the Log icon that appears when placing the mouse cursor over an event type in the Custom Events list on the right.

2. Managing snapshots and mapping eye gaze

Wearable eye tracking devices such as Tobii Pro Glasses 2 produce eye gaze data mapped to a coordinate system relative to the wearable eye tracker and the recorded video, not to static objects of interest in the environment around the participant wearing the eye tracker. For most statistical/numerical analysis to be meaningful, the collected eye-tracking data needs to be mapped on to objects of interest and into a new coordinate system with its origin fixed in the environment around the participant. TobiiPro Glasses Analyzer addresses this challenge by allowing the user to map eye gaze data onto still images (snapshots) of environments and objects of interest in two different ways; either semi-automatically or fully automatically with the Real-World Mapping function. Real World Mapping is Tobii Pro’s software technology for automatic mapping of gaze data from Glasses 2 onto a snapshot (such as a landmark). In Tobii Pro Glasses Analyzer users will use the feature Automatic gaze mapping to map gaze onto a snapshot. With the result, the user can complete or override with manual coding and aggregate data from multiple participants. The snapshots images are typically created by the data collector or the researcher by using a standard digital camera, for details see “Tobii Pro Glasses 2 – Analyzer manual” section: Appendix G Snapshot Considerations When Using Real-World Mapping.

Snapshots created from multiple images do not work flawlessly with Real-World Mapping at the moment. To make the manual mapping process efficient, Tobii Pro Glasses Analyzer lets you map entire fixations on a snapshot with just one click, rather than mapping each data point individually. If you have chosen to map data when the Raw Data fixation filter option is enabled, the data will be mapped gaze point by gaze point. Gaze data from a recording can be mapped on one or several snapshots.

2.1. Importing snapshots

Snapshots are still images of environments, areas or objects of interest relevant to the study.
Snapshots are typically created by the data collector or researcher by using a standard digital camera.

Requirements for snapshot images:
• Less than 25 megapixels
• PNG or JPG file format

Snapshots created from multiple images that are stitched together into one image are allowed as long as the final snapshot file matches the snapshot requirements above. Stitched images are images that are put together from a series of images covering a greater area than the camera was capable of covering in just one shot. Snapshots (still images) can be imported either from the Dashboard menu or from the Tools panel within a Replay tab.

To import a snapshot from the Dashboard Menu:

  1. In the Dashboard Menu, click Import > Snapshots, the import dialog will open.
  2. Locate the image file (*.png or *.jpg) on your computer that you want to use as snapshot and click Open. An import progress bar appears.
  3. Once the snapshot image has been imported, click OK.

To import a snapshot from the Tools Panel in a replay tab:

  1. Locate the Gaze Data Tool in the Tools panel on the right.
  2. Select the Snapshots tab.
  3. To the right of the text “Snapshot images”, click the”+” icon. The Import snapshot dialog box opens.
  4. Locate the image file (*.png or *.jpg) on your computer you want to use as a snapshot and click Open. An import progress bar appears.
  5. Once the snapshot image has been imported, click OK.

2.2. Mapping data onto a snapshot

Mapping data onto a snapshot manually

  1. If not already enabled, click the Snapshots switch just below the video replay to enable mapping.
  2. Locate the Gaze Data Tool in the Tools panel on the right.
  3. Select the Snapshots tab.
  4. Select/Deselect the Automatically step to next fixation checkbox. Selecting the Automatically step to next fixation checkbox will cause the paused replay to automatically jump to the next fixation/raw data point on the timeline, as the previous one is already mapped. This eliminates the need to use arrow keys to step forward manually on the timeline.
  5. In the grid/list of snapshot images, select the snapshot onto which you want to map data. The Snapshot appears next to the recorded scene camera video. At any time during mapping of data, you can switch back and forth between different snapshots without losing mapped data.
  6. While skimming through the recording replay, locate and pause the video at the start of the section that you want to map onto the selected snapshot.
  7. To map data onto the snapshot, first, locate the gaze data point (circle superimposed on the video) in the recorded video. Click once in the corresponding location on the snapshot image as precisely as possible.
  8. Continue this process until all data has been mapped onto the active snapshot. As data points are mapped onto the snapshot, the snapshot timeline will indicate at which times data points have been mapped.
  9. Make sure to replay the recording straight through to verify that data has been mapped correctly onto the snapshot.

Mapping data onto a snapshot automatically with Real-World Mapping

  1. If not already enabled, click the Snapshots switch just below the video replay to enable mapping.
  2. In the grid/list of snapshot images, select the snapshot onto which you want to map data. The Snapshot appears next to the recorded scene camera video.
  3. Select the interval you want to map automatically on the timeline. This can be done by placing the yellow bars found on the timeline to the time you want to map.
  4. Right-click on the chosen interval, or click the ellipsis “(…)” located directly over the timeline, and choose “Run automatic mapping”. If needed, you can zoom in the timeline to make the interval selection easier. The interval is now placed in the processing queue and Real-World Mapping starts the automatic mapping.
  5. Now you can choose to create another mapping task by repeating steps 4 to 6 and place it in the processing queue, or if you don’t have any more pending tasks, continue to step 8.
  6. You can check the jobs placed in the queue by clicking the number on the top right end of the window.
  7. When the automatic mapping is completed, a diagram is shown on the timeline with the confidence results for every frame. This diagram shows how Real-World Mapping classifies each point of the automatic mapping. A high bar indicates that Real-World Mapping thinks the mapping has a high confidence; a lower bar means that Real-World Mapping could not determine the mapping with confidence — it could be a good mapping as well as a bad one.
  8. (Optional) You now have the possibility to complete the analyzed confidence results by manually
    coding/correcting them.

    • Go to the areas of the timeline with low confidence intervals and check whether the gaze
      points on the snapshot correspond with the gaze points in the recorded movie.
      There is no way to add or delete vertices on an existing Area of Interest (AOI) at present. Tobii
      is constantly improving the performance of Real World Mapping
    • For each point, you can now choose to either remove the point, by pressing Delete or by right-clicking on the point in the image and choose Delete, correct the point by manually place it where it should be, just like you do in manual mapping described earlier, or leave the point as
      it is.
    • The manually coded frames are marked in with a solid green color without a graph. In the snapshot image, the automatically generated mapping is marked with a green circle, and the manually coded mapping is marked with a red circle. Over-ridden, automatically mapped, points are marked with a grey circle.
    • Keep repeating this procedure until you are satisfied.
  9. View the result in gaze replay

2.3. Visualizing eye tracking data

In the Visualizations tool in Tobii Pro Glasses Analyzer, data can be visualized using heat maps and gaze plots. Heat maps can be of great value when creating reports, papers or presentations as they help you summarize large quantities of data in an intuitive way. Heat maps are created on top of snapshots. A heat map uses different colors to illustrate the number of fixations participants made within certain areas of the snapshot or for how long they fixated within that area. Red usually indicates the highest number of fixations or the longest time, and green the least, with varying levels in between.
Gaze plots can be used to illustrate the gaze pattern of a single test participant throughout the entire eye tracking session or of several participants in a short time interval. The visualizations are very hard to create when dealing with constantly changing environments, it is not recommended to make visualizations when experimenting in- or outdoors in a changing environment.

Creating heat maps and gaze plots

To create a heat map:
To be able to create heat maps on snapshots, at least one snapshot in the project has to have the gaze data mapped onto it.

  1. Select Visualizations in the Dashboard Menu. A Visualizations tab opens.
  2. In the Visualization Type and Settings tool, select heat map.
  3. In the Tools panel on the right, in the Analysis Sets tool, select the snapshot (Analysis Set) that you want to use as the base of your visualization.
  4. In the Tools panel on the right, in the Data Selection tool, select/deselect the recordings and/or intervals that you want to visualize in the heat map. To see the intervals included click the arrows to the left of the recording checkboxes to expand the view. An interval is a subset of mapped data associated to a specific recording. These subsets are generated automatically when there is a gap of data for at least 5 seconds in the mapped data.
  5. In the Tools panel, in the heat map settings tool, in the Type drop-down menu, select the calculation basis for the heat map
    • Absolute count — calculated by the number of fixations (or gaze data samples if using raw data).
    • Absolute duration — calculated by the duration of fixations (or gaze data samples if using raw data).
    • Relative count — calculated by the number of fixations relative to the total number of fixations made by the participants in the Analysis set (or gaze data samples instead of fixations if using raw data).
    • Relative duration — calculated by the duration of the fixations relative to the sum of all fixation durations mapped in the Analysis set on the snapshot (or gaze data samples instead of fixations if using raw data).
  6. The heat map is now drawn on top of the snapshot image.

To generate a gaze plot:
The gaze plot visualization shows the sequence and position of fixations (dots) on a snapshot image. The size of the dots indicates the fixation duration and the numbers in the dots represent the order of the fixations. Gaze plots can be used to illustrate the gaze pattern of a single test participant throughout the entire eye tracking session or of several participants in a short time interval.

  1. Select Visualizations in the Dashboard Menu. The Visualizations tab will open.
  2. In the Visualization Type and Settings tool, select gaze plot.
  3. In the Tools panel on the right, in the Analysis Sets tool, select or import the snapshot (Analysis Set) that you want to use as the base of your visualization.
  4. In the Tools panel on the right, in the Data Selection tool, select/deselect the recordings and/or intervals that you want to visualize in the gaze plot. To see the intervals included click the arrows to the left of the recording checkboxes, to expand the view. An interval is a subset of mapped data associated to a specific recording. These subsets are generated automatically when there is a gap of at least 5 seconds in the mapped data.
  5. The gaze plot is now drawn on top of the snapshot image.

Heat maps and gaze plots can be saved as image files to be incorporated later into reports.
Available image file formats are *.png and *.jpg.

To save a heat map:

  1. Right-click within the heat map area. A context menu appears with the option to “Save to File…”
  2. In the Context menu, select Save to File… A Windows File Manager dialog box opens.
  3. In the file manager dialog box, locate the folder you want to save the file in.
  4. In the File name field, enter a file name for your image.
  5. In the Save as Type drop-down menu, select the desired file type (*.png or *.jpg). (For images with transparent backgrounds, the file type must be *.png to maintain the transparency)
  6. Click Save to save the image.