[PD] pix_multiblob and tracking multiple objects

Antoine Villeret antoine.villeret at gmail.com
Wed Apr 17 23:09:20 CEST 2013


the segmentation method (how you extract what is your interest from the
rest of the image) is very critical in video tracking
background subtraction is a basic way to extract blob and it works only in
certain conditions of light (if you want to track something outdoor, you
should use an adaptive background subtraction method)
moreover, there is no general method to do video tracking, it depends on
what you want to track and how it is filmed

so, the first thing is to have a good image, with not too much lighting
changes, good contrast between background and features to track
then you can start thinking about segmentation, and the
segmentation accuracy depends on the quality of the video
you may need to do something more than just background subtraction, for
example, you could apply some morphological filter to remove noise
after that, you can start tracking
you could also apply a threshold on the blob size to not track very small
blob of interest are often surrounded by very small blobs due to
segmentation noise

but you can have a look at pix_opencv objects,
there is [pix_opencv_blobtrack] which implements a whole processing chain,
including foreground extractor, blob detector, blob tracker and follower
I'm not sure it's included in pd-extended, but you can find some binaries
on build server

hope this help


do it yourself

2013/4/17 Ska Frenz <skafrenz at gmail.com>

> Hi everyone, this is my first time on the pd-list so I hope I won't do
> anything wrong.
> I'm writing here to get some help about pd tracking objects (pix_blob..).
> I'm using the background subtraction method, to track objects and I need
> help to understand how I can track multiple objects with multiples
> different blobs. I'm trying the pix_multiblob and yes, it show 2 blobs..but
> they track the same object. Then basically I do not understand how can I
> make the first blob to follow just one object for all the time that
> specific object is inside the webcam rectangle, and the second blob to
> track another separate object. I cannot find any material that clearly
> talks about this.I attached the patch I'm working on. I'd love to see some
> well-explained examples if you know where to get them.
> Thank you very much for your help :)
> Francesco
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