Configuring the eye tracker with a "non-standard screen" or physical scene

Tobii Pro eye trackers such as the Pro Spectrum, Pro X3-120, Pro Nano, Pro TX300, Pro X2-30, Pro X2-60,  can be used in different types study setups, not just attached to a computer monitor which is the most common situation. For example, the eye trackers can be used to record gaze data relative to a physical scene, a TV screen, mobile device stand, or a projection screen. In order for the eye tracker to map the gaze data correctly, the user must measure a few parameters related to the geometry of the eye tracker and mapping plane (i.e. your screen, TV or object), and provide that information to the eye tracker. The configuration can be done in different ways depending on the software you will use to present and record the data. Use the table below to choose which application to use to configure your eye tracker.

Using the Pro Eye Tracker Manager to configure the eye tracker

The Pro Eye Tracker Manager has similar functionality as the Eye Tracker Browser, with additional features, such as the possibility of performing a calibration and evaluating the results.

To install the Pro Eye Tracker Manager:

1. Download the application from the web (links: Windows, Mac OS, and Linux)
2. Follow the on-screen instructions to complete the installation.

To configure the eye tracker with the screen or physical tracking plane:

1. Open the Eye Tracker Manager. If your eye tracker card does not show up, wait for 1 minute, if it still does not show up unplug the eye tracker from the USB port and reinsert it.  If this does not work, please restart your computer and run the installation again.
2. Click on the eye tracker card.
3. On the Overview tab, locate the Display setup setting and click the ellipses icon next to the text box. On the dropdown menu click New.
4. Select Advanced setup and click the Next button.
5. Measure the height and width of the active display area of the screen or physical plane, using a measuring tape. The active display area is represented by the area on which the calibration is performed. For monitors, TV screens and other displays, measure the size of the visible active area on the screen where you can see the actual image. For projected displays, measure the size of the visible projection on the display. In a setup where the stimuli are filmed by a scene camera, the active display area must be calculated based on the calibration grid size used. Enter the value in millimeters in the respective Height and Width text boxes, then click the Next button.  
6. Measure the angle between the vertical plane and the screen, using an angle meter. In a scene camera setup (Pro Lab) measure the angle between the vertical plane and your calibration plate. If the display is tilted forward you should enter a negative angle (use “-” in front of the value). If the active display is completely vertical the angle value is 0. In a scene camera setup where you want to track objects on a horizontal table, the angle would be 90 degrees. Enter those values in degrees in the Angle text box. Click the Next button.
7. In the next step, measure the distance from the measuring point on your eye tracker (described in the eye tracker user manual) to the front of the screen, or in a scene camera setup to the physical plane. If the measuring point on the eye tracker is located behind the active display, enter a negative distance (use “-” in front of the value). Enter the value in millimeters in the Distance text box, then click the Next button.
   Note: Always make sure that the distance to the screen or plane is long enough for the eye tracker to track the entire area. Please read eye tracker user manual for more information about the tracking range of the eye tracker.
8. Measure the height difference between the measuring point on the eye tracker and the bottom of the active display area. If the active display is located below the measuring point on the eye tracker (for example, in a setup with a projector and projecting screen) the value will be negative. Enter the value with a “-” in front to signify it as a negative value. Enter the value in millimeters in the Height from x to y text box, then click the Next button.
9. Next, measure the angle of the eye tracker, by placing an angle meter on top or against the front surface of the eye tracker. Enter those values in degrees in the Angle text box. Click the Next button.
10. Give your screen configuration a name so that you can recover the settings later. Type it in the Display Setup Name text box, then click the Save button. Your configuration is now available and selected in the Display setup drop-down menu. 
11. Test the screen configuration by performing a calibration. If you are tracking a physical plane instead of a screen the calibration must be done in Pro Lab.

If you had already created a preset and want to modify it, go to step 3, select the preset you wish to modify, and instead of selecting New on the drop-down menu, click on the edit icon (pencil).

All parameters are measured in relation to a reference point on the eye tracker hardware. The reference point varies depending on which eye tracker model you are using. Please see the User's Manual for your eye tracker for details.

You must measure and specify all the parameters as accurately as possible to maintain good eye tracking data quality.

Configuring the eye tracker in Pro Studio

To access the X Series Eye Trackers Configuration Tool in Tobii Studio:

1. Click the Tools menu and select Settings.
2. In the Global Settings dialog box, click the Eye Tracker tab, select the eye tracker from the list and click the X Config Tool... button. The configuration window opens.
3. Measure and enter the different parameters, relevant to your setup in the respective fields and following the instructions in the figures.
4. Click on Save to Eye Tracker to send the configuration to the eye tracker.
5. Recommended: click on Save to File, to be able to save a .xcfg file locally on your computer, to later access and change the configuration if necessary.
6. When you have finished with your configuration close the configuration window.
7. Test your configuration by performing a calibration and verification test.

Configuration  parameters

All parameters are measured in relation to a reference point on the eye tracker hardware. The reference point varies depending on which eye tracker model you are using. Please see the User's Manual for your eye tracker for details.

The configuration tool has the following parameters:

Units — Select the unit you want to use for measuring the distances: inches or centimeters.

Active Display Size — The correct display or stimuli size must always be added to the configuration tool. The Active Display Area is represented by the area on which the calibration is performed. For monitors, TV screens and other displays, measure the size of the visible active area on the screen where you can see the actual image. For projected displays, measure the size of the visible projection on the display. In a setup where the stimuli are filmed by a scene camera, the active display area must be calculated based on the calibration grid size used.

Eye tracker angle  — Use a digital angle gauge or similar tool to measure the angle of the eye tracker. In many setups, the angle is commonly around 25 degrees.

Display angle —  Measure the angle between the vertical plane and the active display using the digital angle meter. In a scene camera setup, measure the angle between the vertical plane and the calibration grid. If the display is tilted forward you should enter a negative angle (use “-” in front of the value). If the active display is completely vertical the angle value is 0. In a scene camera setup where you want to track objects on a  horizontal table, the angle would be 90 degrees.

Height difference —  Measure the height difference between the measuring point on the eye tracker and the bottom of the active display area. If the active display is located below the measuring point on the eye tracker (for example, in a projector setup) the value will be negative. Enter the value in the X Configuration Tool with a “-” in front to signify it as a negative value.

Distance  —  Measure the distance from the measuring point on the eye tracker to the front of the active display on the monitor, projection screen, or TV screen, or in a scene camera setup to the virtual screen. If the measuring point on the eye tracker is located behind the active display, enter a negative distance (use “-” in front of the value).

Use Side Offset— If the Eye Tracker is not placed right in front of the screen with the axis horizontally aligned, enter the side offset value, measured from the center of the active display to the center of the eye tracker. Enter a negative value if the eye tracker is located to the left of the center as seen from the front.

Use Rotation — If the eye tracker is not placed parallel with the display or tracked object enter the value of the angle between the back of the eye tracker and the active display. If the eye tracker is rotated clockwise, enter a negative value.

You must measure and specify all the parameters as accurately as possible to maintain good eye tracking data quality.

Using the Eye Tracker Browser to configure the eye tracker

The Eye Tracker Browser is an application that allows you to set up different parameters of the eye tracker, update the eye tracker firmware and troubleshoot the connection and performance.

To install the Eye Tracker Browser:

1. If available, plug in the USB memory stick provided with your eye tracker and run the Tobii Eye Tracker Browser installer on your Windows computer. Otherwise download the application from the web (link: Windows).
2. Follow the on-screen instructions to complete the installation.

To access the configuration tool:

1. Open the Eye Tracker Browser (Start > Programs > Tobii > Tobii Eye Tracker Browser). When the Eye Tracker Browser opens, a list of the discovered eye trackers is displayed.
2. Select your Tobii Pro eye tracker from the list and click the Config Tool... button. The configuration window opens.
3. Measure and enter the different parameters, relevant to your setup in the respective fields and following the instructions in the figures.
4. Click on Save to Eye Tracker to send the configuration to the eye tracker.
5. Recommended: click on Save to File, to be able to save a .xcfg file locally on your computer, to later access and change the configuration if necessary.
6. When you have finished with your configuration close the configuration window.
7. Test your configuration by performing a calibration and verification with your stimulus presentation software.

Configuration  parameters

All parameters are measured in relation to a reference point on the eye tracker hardware. The reference point varies depending on which eye tracker model you are using. Please see the User's Manual for your eye tracker for details.

The configuration tool has the following parameters:

Units — Select the unit you want to use for measuring the distances: inches or centimeters.

Active Display Size — The correct display or stimuli size must always be added to the configuration tool. The Active Display Area is represented by the area on which the calibration is performed. For monitors, TV screens and other displays, measure the size of the visible active area on the screen where you can see the actual image. For projected displays, measure the size of the visible projection on the display. In a setup where the stimuli are filmed by a scene camera, the active display area must be calculated based on the calibration grid size used.

Eye tracker angle  — Use a digital angle gauge or similar tool to measure the angle of the eye tracker. In many setups, the angle is commonly around 25 degrees.

Display angle —  Measure the angle between the vertical plane and the active display using the digital angle meter. In a scene camera setup, measure the angle between the vertical plane and the calibration grid. If the display is tilted forward you should enter a negative angle (use “-” in front of the value). If the active display is completely vertical the angle value is 0. In a scene camera setup where you want to track objects on a  horizontal table, the angle would be 90 degrees.

Height difference —  Measure the height difference between the measuring point on the eye tracker and the bottom of the active display area. If the active display is located below the measuring point on the eye tracker (for example, in a projector setup) the value will be negative. Enter the value in the X Configuration Tool with a “-” in front to signify it as a negative value.

Distance  —  Measure the distance from the measuring point on the eye tracker to the front of the active display on the monitor, projection screen, or TV screen, or in a scene camera setup to the virtual screen. If the measuring point on the eye tracker is located behind the active display, enter a negative distance (use “-” in front of the value).

Use Side Offset— If the Eye Tracker is not placed right in front of the screen with the axis horizontally aligned, enter the side offset value, measured from the center of the active display to the center of the eye tracker. Enter a negative value if the eye tracker is located to the left of the center as seen from the front.

Use Rotation — If the eye tracker is not placed parallel with the display or tracked object enter the value of the angle between the back of the eye tracker and the active display. If the eye tracker is rotated clockwise, enter a negative value.

You must measure and specify all the parameters as accurately as possible to maintain good eye tracking data quality.