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We use structures cvtrack and cvblob in programs for blob detection but I am unable to find the difference between the two structures as the structure members for both the types are same.

user2874456
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  • In which OpenCV module is CvTrack defined? I couldn't see it in either OpenCV or Cvblobslib. – Bull Oct 13 '13 at 11:34
  • CvTrack is defined in Cvblobslib only. You can check its code in the header file at /usr/local/include/cvblob.h. – user2874456 Oct 13 '13 at 13:35
  • I think you must be using the cvblob library, not cvblobslib (which doesn't have a cvblob.h) – Bull Oct 13 '13 at 14:31

2 Answers2

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You can use cvBlob to detect and draw figures defined by contours (blobs). then you can track them, from one frame to another. For this you use cvTracks, which gives you a label and a lifetime. you can give also a lifetime limit (if the blob is not detected in one frame, it is saved for a couple of frames in order to detect it again if it appears again, if the lifetime pass, it is removed and cosidered a new blob if it is detected again). Then in some implementations you have a lifetime limit for being active (it does the opposite, after it is active a couple of frames, it is considered a new blob). You can see an example here.

Gabriel Bursztyn
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There are two different blobs libraries with similar names: CvBlobsLib and cvblob

In cvblob (version 0.10.4), the CvTrack struct is similar but not identical to CvBLob. CvTrack has these members that are not present in CvBlob:

unsigned int    lifetime
// Indicates how much frames the object has been in scene.
unsigned int    active
// Indicates number of frames that has been active from last inactive period.
unsigned int    inactive
//Indicates number of frames that has been missing.
Bull
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  • I got that. Moreover I wanted to know the role of CvTrack struct in the programs. Could you please tell me that ? – user2874456 Oct 13 '13 at 21:10