ScreenBasedMonocularCalibration

Provides methods and properties for managing monocular and bi-monocular calibrations for screen based eye trackers. This type of calibration is not supported by all eye trackers. Check the DeviceCapabilities of the eye tracker first!

calib = ScreenBasedMonocularCalibration(tracker)

Enter Calibration Mode
Leave Calibration Mode
Collect Data
Discard Data
Compute and Apply Calibration
Code Example
See Also
Version

Enter Calibration Mode

Enters the Calibration Mode and the Eye Tracker is made ready for collecting data and calculating new calibrations.

calib.enter_calibration_mode()

Leave Calibration Mode

Leaves the Calibration Mode.

calib.leave_calibration_mode()

Collect Data

Collects data for a calibration point for the selected eye(s). The point argument is the point on the display the user is assumed to be looking at and is given in the active display area coordinate system.

Parameters: coordinates (x,y) of the calibration point. Parameters: eye_to_calibrate, an instance of the enum SelectedEye selected eye to calibrate

Returns: an instance of the class CalibrationStatus

calib.collect_data(coordinates,eye_to_calibrate)

Discard Data

Removes the collected data for the specified eye(s) and calibration point.

Parameters: coordinates (x,y) of the calibration point. Parameters: eye_to_calibrate, an instance of the enum SelectedEye selected eye to calibrate

calib.discard_data(coordinates,eye_to_calibrate)

Compute and Apply Calibration

Uses the collected data and tries to compute calibration parameters. If the calculation is successful, the result is applied to the eye tracker. If there is insufficient data to compute a new calibration or if the collected data is not good enough then the calibration fails and will not be applied.

Returns: an instance of the class CalibrationResult

calib.compute_and_apply()

Code Example

%% MOnocular Calibration Sample
clear;

Tobii = EyeTrackingOperations();

eyetracker_address = 'Address of the desired device';
% Example:
% eyetracker_address = 'tet-tcp://172.28.195.1';
try
    eyetracker = Tobii.get_eyetracker(eyetracker_address);
catch ME
    if (strcmp(ME.identifier,'EyeTrackerGet:error204'))
        fprintf('Unable to connect eye tracker.\n');
        return
    end
end
calib = ScreenBasedMonocularCalibration(eyetracker);

try 
    calib.enter_calibration_mode()
catch ME
    if (strcmp(ME.identifier,'EnterCalibrationMode:error210'))
        fprintf('The previous calibration was not completed!\n');
        calib.leave_calibration_mode()
        fprintf('Calibration is restarted\n');
        calib.enter_calibration_mode()
    else
        fprintf('%s\n', ME.identifier);
        return
    end
end
points_to_collect = [[0.1,0.1];[0.1,0.9];[0.5,0.5];[0.9,0.1];[0.9,0.9]];

% Desired eye(s) to be calibrated.
eye_to_calibrate = SelectedEye.BOTH;

% When collecting data a point should be presented on the screen in the
% appropriate position.
for i=1:size(points_to_collect,1)
    collect_result = calib.collect_data(points_to_collect(i,:), eye_to_calibrate);
    fprintf('Point [%.2f,%.2f] Collect Result: %s\n',points_to_collect(i,:),char(collect_result.value));
end

calibration_result = calib.compute_and_apply();
fprintf('Calibration Status: %d\n',calibration_result.Status.value.value);

% After analisyng the calibration result one might want to re-calibrate
% some of the points
points_to_collect = [[0.1,0.1];[0.1,0.9];[0.5,0.5];[0.9,0.1];[0.9,0.9]];

% When collecting data a point should be presented on the screen in the
% appropriate position.

points_to_recalibrate = [[0.1,0.1];[0.1,0.9]];

for i=1:size(points_to_recalibrate,1)
    calib.discard_data(points_to_recalibrate(i,:), eye_to_calibrate);
    collect_result = calib.collect_data(points_to_recalibrate(i,:), eye_to_calibrate);
    fprintf('Point [%.2f,%.2f] Collect Result: %s\n',points_to_recalibrate(i,:),char(collect_result.value));
end

calibration_result = calib.compute_and_apply();
fprintf('Calibration Status: %d\n',calibration_result.Status.value.value);

if calibration_result.Status == CalibrationStatus.Success
        points = calibration_result.CalibrationPoints;

        number_points = size(points,2);

        for i=1:number_points
            plot(points(i).PositionOnDisplayArea(1),points(i).PositionOnDisplayArea(2),'ok','LineWidth',10);
            mapping_size = size(points(i).RightEye,2);
            set(gca, 'YDir', 'reverse');
            axis([-0.2 1.2 -0.2 1.2])
            hold on;
            for j=1:mapping_size
                if points(i).LeftEye(j).Validity == CalibrationEyeValidity.ValidAndUsed
                    plot(points(i).LeftEye(j).PositionOnDisplayArea(1), points(i).LeftEye(j).PositionOnDisplayArea(2),'-xr','LineWidth',3);
                end
                if points(i).RightEye(j).Validity == CalibrationEyeValidity.ValidAndUsed
                    plot(points(i).RightEye(j).PositionOnDisplayArea(1),points(i).RightEye(j).PositionOnDisplayArea(2),'xb','LineWidth',3);
                end
            end

        end
end

calib.leave_calibration_mode()

Version

1.10.1.31

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