"Undefined function 'bbox2points' for input arguments of type 'double'" why this error is showing?

% Create the face detector object.
faceDetector = vision.CascadeObjectDetector();

% Create the point tracker object.
pointTracker = vision.PointTracker('MaxBidirectionalError', 2);

% Create the webcam object.
cam = webcam();

% Capture one frame to get its size.
videoFrame = snapshot(cam);
frameSize = size(videoFrame);

% Create the video player object.
videoPlayer = vision.VideoPlayer('Position', [100 100 [frameSize(2), frameSize(1)]+30]);

runLoop = true;
numPts = 0;
frameCount = 0;

while runLoop && frameCount < 400

      % Get the next frame.
      videoFrame = snapshot(cam);
      videoFrameGray = rgb2gray(videoFrame);
      frameCount = frameCount + 1;

      if numPts < 10
          % Detection mode.
          bbox = faceDetector.step(videoFrameGray);

          if ~isempty(bbox)
              % Find corner points inside the detected region.
              points = detectMinEigenFeatures(videoFrameGray, 'ROI', bbox(1, :));

              % Re-initialize the point tracker.
              xyPoints = points.Location;
              numPts = size(xyPoints,1);
              release(pointTracker);
              initialize(pointTracker, xyPoints, videoFrameGray);

              % Save a copy of the points.
              oldPoints = xyPoints;

              % Convert the rectangle represented as [x, y, w, h] into an
              % M-by-2 matrix of [x,y] coordinates of the four corners. This
              % is needed to be able to transform the bounding box to display
              % the orientation of the face.
             bboxPoints = bbox2points(bbox(1, :));

              % Convert the box corners into the [x1 y1 x2 y2 x3 y3 x4 y4]
              % format required by insertShape.
              bboxPolygon = reshape(bboxPoints', 1, []);

              % Display a bounding box around the detected face.
              videoFrame = insertShape(videoFrame, 'Polygon', bboxPolygon, 'LineWidth', 3);

              % Display detected corners.
              videoFrame = insertMarker(videoFrame, xyPoints, '+', 'Color', 'white');
          end

      else
          % Tracking mode.
          [xyPoints, isFound] = step(pointTracker, videoFrameGray);
          visiblePoints = xyPoints(isFound, :);
          oldInliers = oldPoints(isFound, :);

          numPts = size(visiblePoints, 1);

          if numPts >= 10
              % Estimate the geometric transformation between the old points
              % and the new points.
              [xform, oldInliers, visiblePoints] = estimateGeometricTransform(...
                  oldInliers, visiblePoints, 'similarity', 'MaxDistance', 4);

              % Apply the transformation to the bounding box.
              bboxPoints = transformPointsForward(xform, bboxPoints);

              % Convert the box corners into the [x1 y1 x2 y2 x3 y3 x4 y4]
              % format required by insertShape.
              bboxPolygon = reshape(bboxPoints', 1, []);

              % Display a bounding box around the face being tracked.
              videoFrame = insertShape(videoFrame, 'Polygon', bboxPolygon, 'LineWidth', 3);

              % Display tracked points.
              videoFrame = insertMarker(videoFrame, visiblePoints, '+', 'Color', 'white');

              % Reset the points.
              oldPoints = visiblePoints;
              setPoints(pointTracker, oldPoints);
          end

      end

      % Display the annotated video frame using the video player object.
      step(videoPlayer, videoFrame);

      % Check whether the video player window has been closed.
      runLoop = isOpen(videoPlayer);
  end

% Clean up.
clear cam;
release(videoPlayer);
release(pointTracker);
release(faceDetector);

Answer 1

[Walter Roberson]

The function bbox2points() was introduced in R2014b. You might be running with an earlier version of MATLAB.

Answer 2

[Thorsten]

Try

>> which bbox2points

If you get

 'bbox2points' not found.

Than there is no function bbox2points on your computer, or it is in a directory that is not in Matlab's search path. In this case you can either

1. move the file to your current directory, that you can find out with

   pwd

2. or to a directory that you have already added to Matlab's search path. like C:/Users/Faruqui/soft/matlab

3. you can create such a directory, move the file to it and add the directory to Matlab's search path using, e.g.,

addpath C:/Users/Faruqui/soft/matlab