Hello Jonathan!

as i understand it, you want to track only a hand.

i don´t know if you know about the Leap Motion Controller[1].
This one is specialized to detect hands and from what i read in your mail, could really fit.
i have to admit, i havent played with it myself yet...but there is support for pd available [2].

if you want to stick to the pix_openCV library, have a look in the pix_opencv_example
01_opencv_contrours_boundingrect+pmpd_ambient.pd
if you leave out the physical modelling stuff, it is quite usable to track people, maybe hands as well.

If you want to or have to stick to a camera based tracking system, i could see some possible improvements:
as you say
> The idea is to detect hands from an up-facing webcam in order to simulate a
> camera on a touch pad.
if you really want to simulate the hand being tracked on a touchlike surface, why not add a semi-transparent plexiglass layer and place a camera underneath it, similar to the concept behind the reactable.

[1] https://www.leapmotion.com
[2] http://puredatajapan.info/?page_id=1514

regards,
peter


Am 05.12.14 01:12, schrieb Jonathan Aardestrup:

Hello,

I am working on a university project using Pure Data for computer vision in
order to investigate possible advantages or disadvantages in a music
related interaction context.
The idea is to detect hands from an up-facing webcam in order to simulate a
camera on a touch pad.

I've spend some weeks to get familiar with the objects in Gem namely pix
and pix_opencv, but even with objects such as pix_opencv_bgstats or
pix_opencv_bgsubstract, alone or in combination with other objects, have I
been able to get a clear binary image to detect motion from.

If you could possibly have a look at my code and give me some hints to how
I could improve it I would *really* appreciate it! Other suggestions are
also most welcome!

What I want it to do is detect hand (preferably without arm?) and give me
the following readings:
x-pos, y-pos, x-direction, y-direction,  x-acceleration, y-acceleration and
blob size. x and y being for the center of the detected hand. Multiple
blobs would also be great but I can't really understand how to use it so
far.

I've attached one out of many attempts for the right solution.


I am using some objects from pix_opencv library which (in case you don't
already have it) can be found here:

http://giss.tv/wiki/index.php/Opencv_for_PD#DOWNLOAD_.26_INSTALL
<https://mail.aau.dk/owa/redir.aspx?C=AfeyM9F6NEuKyXWfCaqyUJjUEYZM49EIDcxZaejZJa5vTByqA8HawMFTHijqhA-X2zxf8U4Y1A4.&URL=http%3a%2f%2fgiss.tv%2fwiki%2findex.php%2fOpencv_for_PD%23DOWNLOAD_.26_INSTALL>

The best

Jonathan



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