Why is this mistake?
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Hi everyone, i'm working on visiontracekingfaceKLT. I'm tryng to run this code:
faceDetector = vision.CascadeObjectDetector();
videoFileReader = vision.VideoFileReader('tilted_face.avi');
videoFrame = step(videoFileReader); bbox = step(faceDetector, videoFrame);
x = bbox(1); y = bbox(2); w = bbox(3); h = bbox(4); bboxPolygon = [x, y, x+w, y, x+w, y+h, x, y+h];
shapeInserter = vision.ShapeInserter('Shape', 'Polygons', 'BorderColor','Custom',... 'CustomBorderColor',[255 255 0]); videoFrame = step(shapeInserter, videoFrame, bboxPolygon); figure; imshow(videoFrame); title('Detected face');
points = double(points); points(:, 1) = points(:, 1) + double(bbox(1)); points(:, 2) = points(:, 2) + double(bbox(2));
markerInserter = vision.MarkerInserter('Shape', 'Plus', ... 'BorderColor', 'White'); videoFrame = step(markerInserter, videoFrame, points); figure, imshow(videoFrame), title('Detected features');
pointTracker = vision.PointTracker('MaxBidirectionalError', 2);
initialize(pointTracker, double(points), rgb2gray(videoFrame));
videoInfo = info(videoFileReader); videoPlayer = vision.VideoPlayer('Position',... [100 100 videoInfo.VideoSize(1:2)+30]);
geometricTransformEstimator = vision.GeometricTransformEstimator(... 'PixelDistanceThreshold', 4, 'Transform', 'Nonreflective similarity');
oldPoints = double(points);
while ~isDone(videoFileReader)
videoFrame = step(videoFileReader);
[points, isFound] = step(pointTracker, rgb2gray(videoFrame));
visiblePoints = points(isFound, :);
oldInliers = oldPoints(isFound, :);
if ~isempty(visiblePoints)
[xform, geometricInlierIdx] = step(geometricTransformEstimator, ...
double(oldInliers), double(visiblePoints));
visiblePoints = visiblePoints(geometricInlierIdx, :);
oldInliers = oldInliers(geometricInlierIdx, :);
boxPoints = [reshape(bboxPolygon, 2, 4)', ones(4, 1)];
boxPoints = boxPoints * xform;
bboxPolygon = reshape(boxPoints', 1, numel(boxPoints));
videoFrame = step(shapeInserter, videoFrame, bboxPolygon);
videoFrame = step(markerInserter, videoFrame, visiblePoints);
oldPoints = visiblePoints;
setPoints(pointTracker, oldPoints);
end
step(videoPlayer, videoFrame);
end
release(videoFileReader); release(videoPlayer); release(geometricTransformEstimator); release(pointTracker); close all
But it doesn't run, it appears: Attempted to access bbox(1); index out of bounds because numel(bbox)=0.
Error in visionfacetrackingKLT (line 9) x = bbox(1); y = bbox(2); w = bbox(3); h = bbox(4);
So if someone can help me to repair this mistake please do it. I will appreciate that a lot.
1 个评论
Jan
2013-10-1
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回答（2 个）
dpb
2013-10-1
aceDetector = vision.CascadeObjectDetector();
videoFileReader = vision.VideoFileReader('tilted_face.avi');
videoFrame = step(videoFileReader);
bbox = step(faceDetector, videoFrame);
x = bbox(1);
y = bbox(2);
w = bbox(3);
h = bbox(4);
...
Attempted to access bbox(1); index out of bounds because numel(bbox)=0.
Error in visionfacetrackingKLT (line 9) x = bbox(1); y = bbox(2); w = bbox(3); h = bbox(4);
Well, there's no indication of what step is supposed to be but it ends up returning [] for bbox
Hence, since there are no elements in the array, referencing any is an error.
Your mission, should you choose to accept it, is to determine why that is so...or at least provide enough relevant information that someone here can have a clue, perhaps.
Dima Lisin
2013-12-23
1 个投票
It looks like the face detector is not finding any faces in the first frame. You need to account for that in your code. Check bbox is empty, and if so, go to the next frame.
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2013-12-23
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