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matlabmatlab-cvstobject-detectionroi

How to specify ROIs from left to right in MAtlab

I'm a fresher to Matlab. I'm working on vision.CascadeObjectDetector on Mat-lab and is used twice to find-out two different objects(separately trained), say E and K from a video. bbox and bbox2 are respective ROIs. part of code is given below

while ~isDone(videoFileReader)
videoFrame=step(videoFileReader);
bbox=step(letterDetector_E,videoFrame);
bbox2=step(letterDetector_K,videoFrame);
C = vertcat(bbox,bbox2); 
videoOut=insertObjectAnnotation(videoFrame, 'rectangle', C, 'E&K');
step(videoPlayer, videoOut);
end

I want to take each ROI(both bbox and bbox2 considering together) one by one from left two right, top to bottom like reading a page. how can I do that.

Solution

  • I'm not sure what's the format of bbox here, but assuming it is a vector bbox = [xUpperLeft, yUpperLeft, width, height], you simply need to sort by two columns in succession. For this you can use sortrows:

    sortrows(C, [1 2]);

    This sorts the rows of C first by xUpperLeft (the first column), and then by yUpperLeft (the second column). See also a similar question here.