FAQ: Can I change the location of the calibration targets during the calibration routine?

[Sam]

There are two options for changing the calibration / validation target locations.

Option 1:

Changing the overall horizontal and vertical proportion of the Display screen that is being used by the calibration / validation procedures. This can be achieved by either copying the parameters below to the FINAL.INI on the Host PC (see footnote for how to access the .INI files) or by sending commands via your experimental script (see How can I change the calibration / validation target locations? for an example of how to do this with Experiment Builder): 

Code:

calibration_area_proportion 0.88 0.83
validation_area_proportion 0.88 0.83

The first value in each is the horizontal proportion of the screen that is being used and the second value is the vertical proportion of the screen that is being used. The values above are the defaults.

To determine appropriate proportion values based on your stimuli, screen size and eye-to-screen distance, you can use our handy online Calibration Coordinate Calculator.

Option 2:

Alternatively, each calibration / validation target can be precisely specified in pixel coordinates (with the top-left corner of the Display PC as [0, 0]). To do this, some parameters will have to be adjusted. These parameters come from the CALIBRI.INI file, but should be altered either by copying them to the FINAL.INI file, or by sending commands via the experimental script (e.g., Experiment Builder, Psychtoolbox, E-Prime, etc...) before entering the Camera Setup mode. This ensure that the default values in the CALIBRI.INI file are not changed.

• First turn off default targets from:
  
  
  Code:

  generate_default_targets = YES
  
  to
  
  
  Code:

  generate_default_targets = NO
  
  Then, adjust the following parameters:
  
  
  Code:

  calibration_targets = 320,240 320,40 320,440 40,240 600,240 40,40 600,40, 40,440 600,440
validation_targets = 320,240 320,40 320,440 40,240 600,240 40,40 600,40, 40,440 600,440
  
  Each of the parameters contains a set of X, Y pairs. You can specify different values, but IMPORTANTLY, you must preserve the ordering for the pattern.
  
  
  Code:

  ## calibration_targets = <list of x,y coordinate pairs>
;; X,Y pairs of target point positions
;; these are in display coordinates

;; FOR 9-SAMPLE ALGORITHM:
;; POINTS MUST BE ORDERED ON SCREEN:
;; 5  1  6
;; 3  0  4
;; 7  2  8 

;; ordering for points in bicubic ("HV13", 13 pt) cal
;; Point order:
;; 6    2    7
;;   10   11
;; 4    1    5
;;   12   13
;; 8    3    9
  
  Important note, do not change the general pattern of the calibration / validation routines (though the location of the targets can be changed).
  
  Note: If using Experiment Builder, it is recommended to check the Enable Customized Calibration Positions and Enable Customized Validation Positions and then editing the Customized Calibration Positions and Customized Validation Positions properties as illustrated below, rather than editing the FINAL.INI file.
  
  
     

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Both the CALIBRI.INI and FINAL.INI are in the /ELCL/EXE/ folder in the EyeLink partition on the Host PC. The FINAL.INI file can be edited via the file manager software (EyeLink 1000 Plus and EyeLink Portable Duo) or boot the Host PC to Windows (EyeLink II and EyeLink 1000) and edit the file there (the EyeLink partition shows up as another drive when booted to Windows).