[Insight-users] Initial level set capture
Jayant Chauhan
gripened at hotmail.com
Mon, 19 Apr 2004 12:16:13 +0530
<html><div style='background-color:'><DIV class=RTE><BR>I have finally been able to use GeodesicActiveContourImageFilter, and<BR>after setting the isovalue to anything other than 0, I get results, that<BR>is, I get my contour close to the edges, but not exactly on them.</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>1) Could some one please tell me if there is a way of storing the contour<BR>(using ZeroCrossingFilter) after each iteration, ie, if I run my progrm<BR>with the stopping criteria being RMS = 0.002 and max no of iteration =<BR>1000, could I in any way store the contours at a periodic step, say after<BR>every 5 iterations. I finally want to see the movement of the contour.</DIV>
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<DIV class=RTE>2)Another problem I am stuck with is that I want to see the SPEED image, but<BR>can do it only by saving it as a .mha or vtkimage. But I am having trouble<BR>compiling ImageViewer code. Is there no other way of doing this ?? Maybe<BR>changing the speed image in a way so that I can may save it as a PNG file<BR>?? maybe color codes for -ive and +ive??? I really dont know how the speed<BR>image looks like.</DIV>
<DIV class=RTE>3) Another query is regarding the ISOVALUE, how do we decide the ISOVALUE, I<BR>am getting results for ISOVALUE being anything other than ZERO,<BR>If I keep isovalue = 0, it seems the contour stops after sometime, as if<BR>stuck.</DIV>
<DIV class=RTE>4) My last query is regarding my initial level set which I had created in Matlab like this :</DIV>
<DIV class=RTE> initlevel = zeros(240,320);</DIV>
<DIV class=RTE> initlevel(40:225,99) = -1.8;</DIV>
<DIV class=RTE> initlevel(40:225,100) = 1.0;</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>
<DIV class=RTE> initlevel(40:225,251) = -1.8;</DIV>
<DIV class=RTE> initlevel(40:225,2500) = 1.0;</DIV></DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE> initlevel(39,100:250) = -1.3;</DIV>
<DIV class=RTE> initlevel(40,100:250) = 1.3;</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>
<DIV class=RTE> initlevel(225,100:250) = 1.6;</DIV>
<DIV class=RTE> initlevel(226,100:250) = -0.9;</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>I have also set the ReverseExpansionDirection on, using SetRever...(true);</DIV>
<DIV class=RTE> </DIV>
<DIV class=RTE>Now when I start the iterations, the contour seems to be moving in both the directions, that is instead of one rectangle, I now have 2 rectangles, one moving inwards and the other moving outwards, but the fact is that the object lies inside the initlevelset (as I am using the difference image) and there nothing outside. Can anyone help me with this ??</DIV>
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<DIV class=RTE> with regards<BR>Jayant Chauhan</DIV></div><br clear=all><hr>Need quick cash? <a href="http://g.msn.com/8HMBENIN/2743??PS=">Click here ! </a> </html>