Track rain cells

asked 2013-07-23 04:50:00 -0600

Teepe
1 ●1

updated 2013-07-23 06:24:38 -0600

Hello,

I try to use opencv to track rain cell displacement. The cells move slowly, have lot of holes and can disappear. I found blobtrack_sample.cpp and the result is not bad (see fig) but I would like to improve it a little bit. I identified two problem, which i presume can be solved if i change some parameters. First problem : sometimes the ellipse jumps far from the rain cell (especially when rain cell move out from the frame) and try to catch an other rain cell.

Second problem : the background obviously do not change but blob detection is still not very good. How can I do to detect a blob as soon as the pixel is not white ?

I presume that I have to modify some parameters in blobtrack.hpp and blobtrackingauto.cpp...

Thank a lot for any help.

image description

answered 2013-07-23 05:51:43 -0600

Mathieu Barnachon

4678 ●18 ●53 http://www.math-barnac...

Did you try the Kalman filter from the sample? It should prevent jumping from a blob to another. Look at the sample cpp/kalman.cpp.

For the issue of color, look at the parameters of blobtracking here especially filterBy to track darker blob.

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The blobtrack_sample code already use Kalman filter (parameter btpp_name==Kalman) Thank for the reference about the color issue.

I look in the src of blobtrackingauto.cpp and I found these lines concerning the deletion of blob :

        if(r.width &gt; 4 &amp;&amp; r.height &gt; 4 &amp;&amp; r.x &lt; w &amp;&amp; r.y &lt; h &amp;&amp;
            r.x &gt;=0 &amp;&amp; r.y &gt;=0 &amp;&amp;
            r.x+r.width &lt; w &amp;&amp; r.y+r.height &lt; h &amp;&amp; area &gt; 0)
        {   
            aver = cvSum(cvGetSubRect(pFG,&amp;mat,r)).val[0] / area;
            /* if mask in blob area exists then its blob OK*/
           if(aver &gt; 0.1*255)Good = 1;
  }

So I think i could modify the if (...) to avoid my blob to jump to far but I would rather prefer an other solution (I don't feel very comfortable ...(more)

Teepe ( 2013-07-24 03:36:23 -0600 )edit

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