[PD] pix_multiblob and tracking multiple objects

Antoine Villeret antoine.villeret at gmail.com
Thu Apr 18 16:50:10 CEST 2013

concerning the multiple cameras and so on, this was just my need and why
i'm not using CCV
but be sure that i have nothing against CCV, it could be very useful in
lots of context :-)

regarding driver, as i remember, i had issue with IIDC cameras
but this was few years ago

and by "cheap" i refer to some video digitizer with several inputs that
make pd crashing on ubuntu
but i think this is a V4L2 bug, not a pd's one



do it yourself

2013/4/18 John Harrison <john.harrison at alum.mit.edu>

> OK I guess I misunderstood that the original poster was wanting to do all
> of that. I know the latest CCV supports multiple cameras for some sort of
> "big picture" so it may actually do what you are asking but I don't know
> the details so if you say it doesn't support all of that I'll go with your
> claim. I'm sure the OpenCV solutions are great and perhaps in the future
> I'll need to learn more about them as my own needs warrant.
> I haven't had a problem with the drivers on my "cheap" ps3eye V4L2 webcam
> FWIW. I've also done tracking at 120-125fps 320x240 with 3 said webcams and
> "buggy" drivers, all running simultaneously on one machine. No problems.
> John
> On Thu, Apr 18, 2013 at 9:23 AM, Antoine Villeret <
> antoine.villeret at gmail.com> wrote:
>> how is it possible to use several cameras, correct perspective on each,
>> make a big picture with blending and then tracking on that big picture with
>> CCV ?
>> this have been done with Pd and pix_opencv and works great (at least if
>> you're not using a cheap V4L2 cam with buggy drivers)
>> --
>> do it yourself
>> http://antoine.villeret.free.fr
>> 2013/4/18 John Harrison <john.harrison at alum.mit.edu>
>>> FWIW I had just the opposite experience with CCV. CCV has built-in
>>> background adaptive subtraction, smoothing, highpass filter, gain,
>>> contrast, etc. all tweakable. It also tracks blobs uniquely as the original
>>> poster is wanting, which is why I thought of it for their needs. I used
>>> [pix_blobtracker] before and it works OK but I found CCV to be overall a
>>> more robust solution than anything I could efficiently come up with.
>>> I use CCV at 60fps 640x480 w/ a ps3eye on ubuntu 10.04 64 bit and the
>>> CPU load is not significant and reduced from my original Pd-only solution.
>>> My CCV/Pd patch has been on exhibit 24/7 for 5 months now without issue so
>>> it also seems stable. I use CCV version 1.4. I also used CCV on another
>>> exhibit with a Win7 64 bit system and that ran for months as well without
>>> issue. That might have been version 1.5 but I don't remember for sure. I
>>> also know there's a newer version of CCV supporting multiple cameras now,
>>> and I have not had experience with this.
>>> Maybe I'm not understanding the flexibility you are looking for that CCV
>>> is not offering you. All I can imagine is that you can't find a way to
>>> change the order of the filtering. I'm not sure that's something you'll
>>> find you actually need though to improve the result of the blob tracking.
>>> Just my $.02.
>>> -John
>>> On Thu, Apr 18, 2013 at 8:42 AM, Antoine Villeret <
>>> antoine.villeret at gmail.com> wrote:
>>>> i tried CCV one time but i had some driver and performance issues
>>>> moreover, i can't find an easy way to tune the processing chain
>>>> pd is more flexible but, i agree, could be harder
>>>> --
>>>> do it yourself
>>>> http://antoine.villeret.free.fr
>>>> 2013/4/18 John Harrison <john.harrison at alum.mit.edu>
>>>>> I'm not totally clear on the big picture here but it could be you
>>>>> might save yourself a lot of time and effort doing your blob tracking with
>>>>> Community Core Vision (CCV) then sending the blob data to Pd through OSC.
>>>>> After initially doing my blob tracking in Pd only (which did work), I
>>>>> switched to this CCV --> Pd approach and got better results because of all
>>>>> of the built-in filtering etc. that is provided with that open-source
>>>>> cross-platform software.
>>>>> -John
>>>>> On Thu, Apr 18, 2013 at 5:22 AM, Ska Frenz <skafrenz at gmail.com> wrote:
>>>>>> Hi, thank you for the suggestions, I'll check openCv. Can you explain
>>>>>> how to use "morphological filters" to clear up the noise in the image? Are
>>>>>> there examples around? Also, could you please explain me better what do you
>>>>>> mean with "adaptive background subtraction method"?
>>>>>> Thank you for your time :)
>>>>>> francesco
>>>>>> 2013/4/17 Antoine Villeret <antoine.villeret at gmail.com>
>>>>>>> hi,
>>>>>>> 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
>>>>>>> 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
>>>>>>> antoine
>>>>>>> --
>>>>>>> do it yourself
>>>>>>> http://antoine.villeret.free.fr
>>>>>>> 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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