FAQ: How can I change the calibration / validation target locations?

[SR-SUPPORT]

There are three methods to change the size, shape, and location of the calibration and validation targets in Experiment Builder.

1. Rescale the Entire Calibration Area
   By default, targets are presented in a rectangle that covers 88% of the screen horizontally and 83% vertically. You can change this area for all targets. We have a handy online Calibration Coordinate Calculator which given the screen measurements, resolution, and eye to screen distance value, can provide appropriate calibration proportion values. 
   
   At the start of your project, add two EL_COMMAND nodes to define the proportion of the screen you want to use:
   • Command1:
     • Command: calibration_area_proportion
       
     • Text: 0.88 0.88
       Replace the numerical value with your desired X and Y proportions of the screen you want to use for calibration.
       
          
   • Command2:
     • Command: validation_area_proportion
       
     • Text: 0.88 0.88
       Replace the numerical value with your desired X and Y proportions of the screen you want to use for validation.
       
          
   Note: Calibrating only a very small area of the screen is not recommended, even if your stimuli are confined to that area. Targets should only be moved if the participant cannot see them in their default locations or if your calibration area exceeds the trackable range of the system.
   
   
2. Alter Corner Target Locations (9- and 13-Point Calibrations Only)
   This method scales the corner targets inward, creating a more elliptical pattern, which can be helpful when viewing the calibration through a cylindrical viewport, such as in MRI environments.
   
   At the start of your project, add two EL_COMMAND nodes to define the proportion of the screen you want to use:
   • Command1:
     • Command: calibration_corner_scaling
       
     • Text: 0.88
       Replace the numerical value with your proportions of the screen you want to constrain the corner points to
       
          
   • Command2:
     • Command: validation_corner_scaling
       
     • Text: 0.86
       Replace the numerical value with your desired X and Y proportions of the screen you want to use for calibration.
       
          
   Tip: The validation_corner_scaling value should be slightly different from the calibration value to ensure a more robust test of the calibration model.
   
   Note: This can be used in combination with Method 1 mentioned above.
   
   
3. Use Custom Target Locations
   For complete control, you can define your own list of X, Y coordinates for each target. The target points must be defined in a specific order with a few constraints about the positioning of the targets relative to one another. For detailed instructions and the correct point order for each model, please consult the Experiment Builder Manual (Help menu > Contents > Components > Actions > Performing Camera Setup and Calibration).
   
   To enable this feature do the following:
   • Select the CAMERA_SETUP node in your project.
     
   • In its properties, check the box for "Enable Customized Calibration Positions".
     
   • Provide a formatted list of screen coordinates in the specific order required by your chosen calibration model (e.g., HV9).