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Brain picture
Beauchamp Lab

Notes on the SR EyeLink Eye Tracker

The Beauchamp Lab has two SR Eyelink systems: an Eyelink (for MRI scanner use) and an Eyelink Plus (set up in the lab).

Here are notes on setting up the EyeLink Plus:

- connections:

  - laptop to camera via ethernet
  - laptop to display PC via ethernet (USB ethernet port)
  - illuminator to camera

Ethernet connections must be in place before Host Laptop is turned on.

Display PC needs to have IP address manually set to

  - use any web browser to access files on Host Laptop by going to XXX  in address bar

To run an experiment, have the host PC (the laptop) on and have the EyeLink camera running before starting the experiment program, otherwise the program will time out.

Setting up for new monitor is simple: go to the settings on the Host PC, click the screen setup icon, and enter the measurements it asks for.

Starting the EyeLink Eyetracker System:

    1)	Turn on Display PC (the Mac)
    2)	Turn on Host PC (the laptop)
    3)	Select “Eyelink” operating system to initiate startup
    4)	Make sure lens cap is off of camera
    5)	On Mac, open Chrome, and go to the EyeLink bookmark
    6)	On the Mac start the experiment you want to run (should have Eye on white background as the logo)
     a.	E.g. GCWindow
    7)	Experiment program is now running
    8)	Have subject sit with chin on rest, with forehead against bubblewrap, and look forward.
    9)	Start calibration (shortcut is ‘c’) from Host PC
     a.	Hit enter when subject’s gaze is correct. The calibration will advance automatically.
               If it doesn’t, hit ‘a’ to toggle the auto calibrate trigger. Hitting ‘enter’ will accept a point manually.
     b.	If there is a problem with saturation of the image, click ‘autocontrast’ (‘a’ shortcut’)
   10)	After calibration, you can validate the calibration if desired (‘v’ shortcut)
   11)	Start recording the experiment (‘o’ shortcut)

Shutting down the Eyelink System:

    1)	Close the experiment (you can abort in the middle or save the data via a ‘save file’ UI popup if you complete it)
    2)	Click “Shutdown Host” to shutdown the Host PC
     a.	The Host PC will complete shutdown and prompt you to turn off the computer when complete
    3)	Recap the lens
    4)	Shut down the Mac (if desired)

Dongle is required to use the Experiment Builder or Data Viewer programs from EyeLink.

Ricky's Notes on Scanner Eyetracking

1. Camera sensors: We currently have 2 camera sensors: the Eyelink SR 1000 and 1000 Plus. a. Eyelink 1000 Plus

                                                              i.      Has laptop
                                                            ii.      Has Camera sensor built into (non-MR compatible)
                                                           iii.      It is best to use this setup with the laptop outside of the scanner completely.
                                                          iv.      This might be a good setup for remote use (e.g., Bill in the OR)

b. Eyelink 1000

                                                              i.      We have two desktops that work only for Eyelink 1000
                                                            ii.      I moved one desktop to live in Scanner 5 and full set it up
                                                           iii.      The other desktop, I think we should set this one up in S104X and replace the Eyelink 1000 Plus
                                                          iv.      The idea then would be that we could just take off the camera sensor and move it in the behavioral lab or the scanner, whichever one is being used. And if this works well, we could then just buy another sensor and keep each setup permanent.
                                                            v.      For the scanner, we would not gain any benefit from using an Eyelink 1000 Plus because the sensor is not MR-compatible.
                                                          vi.      We are missing a Desktop stand + illuminator and power cable. Marcus can send us a new power cable for free, but a new desktop stand + illuminator would cost ~$3,000. But, he says we should very likely have the stand somewhere, but we did not immediately find it here at BCM. We might do some more digging when you are back.

2. Scanner Mount: a. The wooden mount that made worked out perfectly. We un-mounted the BOLD screen from the trolley and actually just slid the mount over the trolley for the 32” BOLD Screen. The camera and illumination can be some just barely at the bottom of the screen, not a huge obstruction. b. We found a very good convergence between the illumination and camera/lens. These should not really need to be adjusted. We want to keep the camera and the illumination source maximally separated for best results. c. When re-attaching the arm, only the ball on pivot should be adjusted to simultaneously point both at the subject’s right eye. There should not be any need to adjust horizontal position or angle of either the illuminator or the camera lens. We should be able to just point both and focus the camera lens. 3. Adjusting the camera focus and pupil detection: a. How to focus the eyes

                                                              i.      First, use the broad view to make sure the camera is pointed to the eyes. (Press the left arrow to jump between zoom view and broad view).
                                                            ii.      Second, click on the area where the pupil is. This will only look for the pupil within the vicinity of the mouse click.
                                                           iii.      Third, focus the camera lens

1. This requires some twiddling but the idea of the camera focus is to adjust it until the corneal reflection is minimized b. For each subject, there will need to be some manual adjustment of the image intensity segmentation on the Eyelink Computer. The idea is as follows:

                                                              i.      Up Arrow and Down Arrow: Adjust these until the pupil is maximally filled with no black border around it. This should be an intensity level between 75 and 135 out of 255 pixel intensity values
                                                            ii.      +/- keys: Adjust the corneal reflection. Adjust to minimize the size and eliminate the white border around the glint.  

c. Drift check

                                                              i.      Marcus recommends running a Drift check between scanning runs. If the drift check is off, then it might be necessary to rerun the calibration. This sometimes is necessary as subject and/or camera may have moved.

4. DOS commands: a. t – starts tracking b. edit calibr.ini – edit calibration. Better not to actually edit things here, but just note the default values. Override them in the final.ini file or with MATLAB commands. c. edit physical.ini – only edit this when things like the screen size or distance from the camera are changed d. edit final.ini – edit this file to override anything in all other .ini scripts. But MATLAB commands will override even anything in here. Make sure that there are a few break lines at the end of this script though!

Johannes Notes

Must install the Eyelink library for software to work on the Mac.
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