I got this error when this line executes points = detectMinEigenFeatures(rgb2gray(videoFrame), 'ROI', bbox);
I am trying to track face in a video using KLT in Matlab R2014b but I don't know how to remove this error "Expected ROI to be an array with number of elements equal to 4". Can any one help?
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clc;
clear all;
faceDetector = vision.CascadeObjectDetector();
videoFileReader = vision.VideoFileReader('labedit.mp4');
videoFrame = step(videoFileReader);
bbox = step(faceDetector, videoFrame);
videoFrame = insertShape(videoFrame, 'Rectangle', bbox);
figure; imshow(videoFrame); title('Detected face');
bboxPoints = bbox2points(bbox(1, :)); disp(bboxPoints(1,1));
points = detectMinEigenFeatures(rgb2gray(videoFrame), 'ROI', bbox);
figure, imshow(videoFrame), hold on, title('Detected features'); plot(points);
pointTracker = vision.PointTracker('MaxBidirectionalError', 2);
points = points.Location; initialize(pointTracker, points, videoFrame);
videoPlayer = vision.VideoPlayer('Position',... [100 100 [size(videoFrame, 2), size(videoFrame, 1)]+30]);
oldPoints = points;
while ~isDone(videoFileReader)
videoFrame = step(videoFileReader);
[points, isFound] = step(pointTracker, videoFrame);
visiblePoints = points(isFound, :);
oldInliers = oldPoints(isFound, :);
if size(visiblePoints, 1) >= 2 % need at least 2 points
[xform, oldInliers, visiblePoints] = estimateGeometricTransform(...
oldInliers, visiblePoints, 'similarity', 'MaxDistance', 4);
bboxPoints = transformPointsForward(xform, bboxPoints);
bboxPolygon = reshape(bboxPoints', 1, []);
videoFrame = insertShape(videoFrame, 'Polygon', bboxPolygon, ...
'LineWidth', 2);
videoFrame = insertMarker(videoFrame, visiblePoints, '+', ...
'Color', 'white');
oldPoints = visiblePoints;
setPoints(pointTracker, oldPoints);
end
step(videoPlayer, videoFrame);
end
% Clean up
release(videoFileReader);
release(videoPlayer);
release(pointTracker);
Accepted Answer
Dima Lisin
on 28 Feb 2015
Hi Adil,
It looks like the face detector did not detect anything. You have to check whether bbox is empty.
3 Comments
Muhammad Irfan
on 28 Mar 2017
Edited: Muhammad Irfan
on 28 Mar 2017
Any positive response from anyone Jean-Sébastien Herbaux? I have faced same error
More Answers (0)
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