You can include a Tobii Eye Tracker in your Vicon Nexus system, enabling you to output eye tracker position and gaze direction.

To include Tobii Pro Glasses in your Vicon Nexus system, complete the following procedures.

For details of Tobii Pro Glasses properties, see Tobii Pro Glasses node.

Before you begin, ensure your Nexus system is calibrated and that you have created a subject.

Set up Tobii Pro Glasses

To set up your Tobii Pro Glasses for use with Nexus:

1. Follow the instructions provided by Tobii. The quick start guide provided in the Tobii Pro Glasses box provides instructions on preparing and connecting the glasses to the recording unit.

   

2. To use Tobii Glasses software, connect the Tobii Pro Glasses, either through Ethernet or WiFi, by following the instructions provided by Tobii.
   When setting up networking connection properties for an Ethernet port, ensure that you select the required option:
   • For Tobii Pro Glasses 2, select Internet Protocol Version 6 (TCP/IPv6).
   • For Tobii Pro Glasses 3, you can select Internet Protocol Version 4 or Internet Protocol Version 6
3. Calibrate the glasses in the Tobii Glasses software.
   This enables you to check the fit of the glasses before connecting to Nexus.
4. After calibration is complete, close the Tobii Glasses software.

Integrate Tobii Pro Glasses into Nexus

Connect a Tobii Pro Glasses 3 recording unit to the Nexus computer

To connect the Tobii recording unit to the Nexus computer, it must be able to obtain a valid IP address (IPv4 or IPv6).

To enable this, we recommend the following workflow, starting with connecting via Ethernet. Note that this method requires a valid DHCP router. (If you don't have access to a router, see Other connection methods.)

Connect via Ethernet:

From the router (such as a D-Link), connect via Ethernet to:

• An Ethernet network port on the Nexus computer
• The RJ45 port on the Tobii recording unit

If you don't need to connect the Tobii Pro Glasses 3 via Wi-Fi, you can now add the Tobii glasses into Nexus.

Connect via Wi-Fi:

1. Ensure you have successfully connected the Tobii recording unit via Ethernet, as described above.
2. Browse to http://<recording unit serial number>.local/network.html.
3. Either create a new Wi-Fi configuration or select an existing one. To create a new one:
   
   1. Under WiFi, click Create
   2. Set the SSID, network security type, and password, if required.
   3. Click Apply.
4. Disconnect the Ethernet cable.

Other connection methods

If you want to use an alternative way to connect the Tobii Pro (for example, if you don't have access to a router), you may find the following additional information helpful.

Connect to the Tobii 3 directly via Wi-Fi

If you use this connection method, the Tobii Pro Glasses 3 recording unit acts as an Access Point so any device with a spare Wi-Fi card can connect.

• SSID = <recording unit serial number> (eg, TG03B-080200013621)
• Default password = TobiiGlasses

Connect to the Tobii 3 using a direct Ethernet link

This connection method requires some config on the device first:

1. Connect to the Tobii via one of the methods above.
   • If connection is via the direct Wifi connection, go to http://192.168.75.51/network.html (assuming no other config has been done to change the default IP address)
   • If connection is via Ethernet, go to http://<recording unit serial number>.local
2. Do one of the following:
   • Under the wired network settings at the bottom of the page, change the profile to default-link-local and click Apply; or
   • Configure the Tobii to be a DHCP server.
3. Connect the Tobii 3 directly to the PC via Ethernet.

Add the Tobii glasses into Nexus

To add the Tobii Pro Glasses device into Nexus:

1. Ensure the Tobii recording unit is connected to the Nexus computer via Ethernet or WiFi (see Connect a Tobii recording unit to the Nexus computer).
2. Ensure that the Tobii glasses are being worn by a subject in the volume.
   (Tobii glasses connect to Nexus only when the glasses are worn: if no eye is detected, the device is gray in the System Resources tree.)
3. In the System Resources tree, right-click Devices, point to Add Digital Device and then select Add Tobii Pro Glasses 2 or Add Tobii Pro Glasses 3.

   

   Nexus searches for the glasses on the network. When the glasses are discovered, data begins streaming in Nexus. Note that this process can take some time.
4. With the Tobii Pro Glasses device selected in the System tree, in the Properties pane, ensure that in the Sampling Rate field, the required sample rate is selected.

   

5. Before capturing data, for each subject, perform a calibration on each subject in the same way as it is done in the Tobii Glasses software.
   1. Instruct the subject to look at the calibration card, with the card held between 0.5 m and 1.5 m from the subject (for correct placement of the card, see the Tobii documentation).
   2. In the System Resources tree, ensure the required Tobii Pro Glasses device is selected and in the Properties pane, go to the Calibration section and click Start Calibration.

      

      Ensure the subject continues to look at the calibration card.After approximately three seconds, status information is displayed, with a success or fail status at the end of the process.
      
      • If calibration is successful, the Calibration Status changes to calibrated.
      • If calibration fails, see Possible calibration issues for a list of suggested issues, and correct any issues that you identify.

        

        Note that, for Tobii Pro Glasses 2, data that is needed for calibration is created on the SD card and is deleted when the device is deleted. If the connection is lost, projects and participants may be left on the SD card.If no data is received for approximately one second, it is assumed that the connection has been lost and the device reverts to 'discovery' mode to try to re-connect to the device when it becomes available again.
6. The Tobii Pro Glasses 3 mocap integration kit is provided as two marker tree attachments. Attach the mocap integration kit by screwing it into the fittings on the frame of the glasses.
   The Nexus installer provides two VSTs for the two variants of these marker trees. If you require more subjects, you can interchange the left/right trees from each of these two sets. For additional VSTs, contact Vicon Support.
   
7. Load the appropriate VST. The relevant VSTs for the version of the integration kit provided in your Tobii Pro Glasses box are found in:
   C:\Program Files (x86)\Vicon\Nexus2.#\ModelTemplates

   

8. To visualize the gaze data in the Nexus workspace, with the Tobii Pro Glasses device selected in the System tree, go to the General section of the Properties pane and set the Glasses Segment to the name of the segment that the glasses are attached to.

   

   Note that specification of the Glasses Segment is not a requirement for receiving the data from the glasses: it is used for visualization in the Nexus workspace only. Also note that if multiple Tobii Pro Glasses are in use, the additional subjects must have unique segment names. To do this, for each eye tracker, in the Glasses Segment field, specify the subject name followed by a colon and the segment name, for example, SubjectAGlasses:TobiiGlasses and SubjectBGlasses:TobiiGlasses.
9. Ensure that Nexus is running in Kinematic Fit processing mode.
   The eyes are displayed relative to the glasses segment at positions specified by the Left/Right Eye X,Y,Z components, and gaze direction is shown as a line from each eye to the Gaze position.
   The eye itself also rotates to match the Left/Right Gaze value, though this may be difficult to observe.

For details of the resulting data that is reported by Nexus, see Understand output data.

Possible calibration issues

If calibration was not successful, check for these possible issues:

• Calibration card is too close (<0.5m).
• Calibration card is too far away (>1.5m).
• The subject is not looking at the calibration card.
• There are multiple possible calibration targets (multiple cards or objects that look like cards, or the card is visible in the displayed video that is also in view).
• There is too much movement of the eye tracker or card during calibration.

Understand data output

Tobii Pro Glasses outputs are available for:

• Left(Right) Eye X, Y, Z position of the eye with respect to the origin of the glasses segment/scene camera and the diameter of the pupil
• Left(Right) Gaze A three-component vector specifying the direction of the gaze for the eye
• Gaze position The calculated point of focus for the combined gaze with respect to the origin of the glasses segment/scene camera