Calibrating and integrating Dikablis eye tracking

To calibrate your system and use Tracker with Dikablis to track eye movement, complete the following procedures:

Calibrate the Dikablis system and connect it to your Vicon system

1. Connect up the headset, transmitters and receivers that comprise the Dikablis eye tracking system.
2. Ensure the subject is wearing the Dikablis headset and some markers for head tracking.
3. Start the Dikablis Recorder software on the Dikablis system and run the calibration wizard.
4. Connect the Dikablis laptop directly to your Vicon system PC with an Ethernet cable.
5. Set the IP addresses of the Network Interface Cards to an appropriate value. These instructions use 10.0.0.1 on the Dikablis laptop and 10.0.0.2 on the Vicon system PC. (For instructions on how to set IP addresses, see the online help for Windows.)

Calibrate your Vicon system and add in your Dikablis device

1. Aim your Vicon cameras to capture the required volume.
2. Calibrate the cameras in Tracker (see Calibrate Vicon cameras).
3. Set your origin pointing forwards by positioning the T of the wand with the flat part (the top of the T) facing towards the front of the capture volume.

4. When you have a calibrated system, create an object in Tracker from the wand markers. To do this:

   1. In the Resources pane, click the Objects tab and ensure that in the Object Tracking Mode section at the bottom of the tab, Track mode is not selected. This enables you to see unlabeled reconstructions in the 3D Perspective view pane.

      Tip: Viewing unlabeled reconstructions requires additional processing, so for lowest output latency, when you have finished creating objects, click the Track button to change to Track mode. When Track mode is selected, the Track button is green.

   2. In the 3D Perspective view pane, ALT+click and drag to select the markers.

   3. In the Resources pane, click the Objects tab and in the Create Object box, type Wand and then click Create.

5. Adjust the wand's origin so it is on the center marker on the cross of the T.

6. With your subject looking straight ahead, create an object from the head markers and give it a suitable name, such as Head. (You can give it any suitable name, but ensure you use the same name in the following steps.)

7. On the System tab, right-click Devices, point to Add Digital Device, and then click Add Dikablis Eye Tracker.

8. Select Dikablis Eye Tracker and in the Properties pane, enter the values:

   • Name: Eye
   • Head Object: Head
   • IP Address: 10.0.0.1 (or the address of the PC running the Dikabilis software if different from 10.0.0.1)
   • Calibration Object: Wand

9. Make sure the Eye Tracker remains selected on the System tab, change the view pane to Graph view and in the Components list, select Components.

   Two graphs are shown: X and Y, representing the 2D coordinates for the eye's gaze. The values are pixel values from the eyecamera.

10. Check that the eye's gaze is accurately represented by the X and Y values. To do this:

    1. Get your subject to look left. The X value decreases.

       Tip: To see all the data, you may need to click the Scale the graph to fit the horizontal and vertical ranges of data button at the top of the Graph view pane.

    2. Get your subject to look right. The X value increases.
    3. Get your subject to look up. The Y value increases.
    4. Get your subject to look down. The Y value decreases.

    Tip: The X values should not go above 640 or below 0. The Y values should not go above 480 or below 0.

11. Specify the eye offsets.

Specify the eye offsets

1. With the Eye Tracker selected on the System tab, in the Properties pane, enter appropriate values. The following offsets are normally suitable:
   
   • X (mm): -20
   • Y (mm): -40
   • Z (mm): -25

2. Change the view pane to 3D Perspective and look at the Head object.

   The eyeball should be approximately where the eye is, relative to the Head markers.

3. Calibrate the Dikablis eye tracker with Vicon Tracker.

Calibrate the Dikablis eye tracker with Vicon Tracker

1. Get the subject to stand with the wand in their hand so the Head and Wand objects are clearly and consistently visible in the 3D Perspective view.
2. Get the subject to look at the marker at the center of the T on the wand.

3. In the Calibration area of the Eye Tracker Properties pane, click Add.

   The Samples box displays 1.

   Tip: If an error is made during calibration, you can remove the last sample you added by clicking the Remove button.

4. Get the subject to move the wand and repeat step 3.

   The number of samples goes up to 2.

5. Repeat step 4.

   The number of samples goes up to 3 and an eye with an eye vector coming from it appears in the 3D Perspective view pane.

   In the Calibration area of the Properties pane, a Residual value is displayed.

6. Get your subject to keep their head still and move the wand around, following the marker at the center of the T with their eyes.

   In the 3D Perspective view pane, the eye vector now follows the wand.

7. On the System tab, select the Eye Tracker. Change the view pane to Graph.

   Ray X, Ray Y and Ray Z values are displayed, as well as X and Y values.

8. Save your settings.

Save your settings

1. On the System Resources pane, click the Configuration menu button and select Save As.

2. Enter the name DikablisTest.
3. When prompted, select Shared or Private.