function output = plotManualAutoDifference(obj, shoulderSide, normLimitForOutliers)
    % Plot the vectors between auto and manual points.
    %
    % input: normLimitForOutliers
    %
    % The vector is green if below the value given to normLimitForOutliers,
    % otherwise it is red.

    % initialisation
    manual = obj.shoulders.(shoulderSide).manual;
    manualPoints = [];
    
    auto = obj.shoulders.(shoulderSide).auto;
    autoPoints = [];

    % find maximum number of common groove points
    minGroovePoints = min(size(manual.scapula.groove),size(auto.scapula.groove));
    if (minGroovePoints > 0)
        manualPoints = [manual.scapula.groove(1:minGroovePoints,:)];
        autoPoints = [auto.scapula.groove(1:minGroovePoints,:)];
    end

    % create points arrays
    manualPoints = [manualPoints;...
                    manual.scapula.angulusInferior;...
                    manual.scapula.trigonumSpinae;...
                    manual.scapula.processusCoracoideus;...
                    manual.scapula.acromioClavicular;...
                    manual.scapula.angulusAcromialis;...
                    manual.scapula.spinoGlenoidNotch;...
                    manual.scapula.coordSys.origin;...
                    manual.scapula.glenoid.center;...
                    ];

    autoPoints = [autoPoints;...
                  auto.scapula.angulusInferior;...
                  auto.scapula.trigonumSpinae;...
                  auto.scapula.processusCoracoideus;...
                  auto.scapula.acromioClavicular;...
                  auto.scapula.angulusAcromialis;...
                  auto.scapula.spinoGlenoidNotch;...
                  auto.scapula.coordSys.origin;...
                  auto.scapula.glenoid.center;...
                  ];

    % measure norm difference
    manualAutoDifference = vecnorm(autoPoints-manualPoints,2,2);

    % plot the difference vectors
    for i = 1:size(manualAutoDifference,1)
        if (manualAutoDifference(i) > normLimitForOutliers)
            % outlier
            color = 'red';
        else
            % valid point
            color = 'green';
        end
        differenceLine = [manualPoints(i,:);...
                          autoPoints(i,:)];

        plotHandle(i) = plot3(differenceLine(:,1),differenceLine(:,2),differenceLine(:,3),...
            ':x',...
            'Color',color,...
            'LineWidth',3);

        hold on
    end

    output = plotHandle;
end