Using the X configuration tool

A Tobii Pro X-series eye tracker such as the Pro TX300, Pro X2-30, Pro X2-60, Pro X3-120 can be used in many different setups, not just attached to a computer monitor which is the most common situation. For example, it can be used to perform eye tracking relative to a physical scene, a TV screen, mobile device stand, or a projection screen. For all this to work, the user must provide some information to the eye tracker about the physical setup and various parameters. This is done using the X Configuration tool. When using the eye tracker without being mounted on a standard laptop screen or monitor, you must specify all the positioning parameters in the X Configuration Tool as accurately as possible to maintain good eye tracking data quality.

The X Configuration Tool can be accessed via the Tobii Eye Tracker Browser software which is installed together with Tobii Pro Studio.

To install the Eye Tracker Browser:

1. Plug in the USB memory stick provided with your eye tracker and run the Tobii Eye Tracker Browser installer on your Windows computer. Alternatively download the Tobii Eye Tracker Browser from the web.
2. Follow the on-screen instructional steps to complete the installation.

To access the X 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 X Configuration Tool opens.

The X Configuration Tool parameters

The X Configuration Tool has a number of parameters that must be defined for the eye tracker to operate correctly when used in special setups. 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 or the illustration in the X Configuration Tool on your computer. The X 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 in the X 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 (A) — Use a digital angle gauge or similar tool to measure the agle of the eye tracker. In many setups the angle is commonly around 25 degrees.

Display angle (B) —  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 (C) —  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 (D) —  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.

Save to Eye Tracker — Once you have entered all the needed parameters corresponding to your setup, you must click Save to Eye Tracker in order to start using this configuration. The parameters will then be sent to the eye tracker and the eye tracker will immediately be properly configured. When you change any parameter value in the tool, the button must be pressed again for the eye tracker to get the new settings.

Save to File — You also have the option of saving the configuration as an .xcfg file locally on your computer by clicking the Save to File... button and setting the name and location of the file. Click Load from File... to load a previously saved .xcfg configuration file. This is useful if you want to save a particular configuration of a setup to be able to reuse it at a later point in time or from another computer.

Please see the User's Manual for your eye tracker model for more detailed information about how to use and configure the eye tracker in various situations by using th Tobii X Config Tool.