[PD] pix_multiblob and tracking multiple objects

Antoine Villeret antoine.villeret at gmail.com
Thu Apr 18 16:23:28 CEST 2013

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
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

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
>>>>>> _______________________________________________
>>>>>> Pd-list at iem.at mailing list
>>>>>> UNSUBSCRIBE and account-management ->
>>>>>> http://lists.puredata.info/listinfo/pd-list
>>>> _______________________________________________
>>>> Pd-list at iem.at mailing list
>>>> UNSUBSCRIBE and account-management ->
>>>> http://lists.puredata.info/listinfo/pd-list
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20130418/eef89662/attachment.htm>

More information about the Pd-list mailing list