Hi Baoyun,<br><br>You are right that if you set 4 phases in the levelset, then no phase will shrink to empty.<br><br>In ITK, if you use the classes on ScalarChanAndVeseLevelSetImageFilter, you can separately encode the 3 regions in 3 separate level-set functions and these functions compete with each other for the segmentations at the boundaries. You can also control each level-set parameters separately. <br>
<br>If you have N objects, then you can make use of a built-in kd-tree optimization that speeds up the approach. Each levelset function is only defined in a small subdomain containing your object instead of the whole image thereby saving space.<br>
<br><br>Kishore<br><br><div class="gmail_quote">On Fri, Mar 26, 2010 at 10:48 AM, Baoyun Li <span dir="ltr"><<a href="mailto:baoyun_li123@yahoo.com">baoyun_li123@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<div>Dear All:</div>
<div> </div>
<div>Thanks for your reply, now seems I undertand the question more.</div>
<div> </div>
<div>According to Wanlin's paper, I need to encoding the 2 level set to 3 phase if I want to 3 segmenations. If I need 4 segmentation, I need to encode the levelset to 4 phases.</div>
<div> </div>
<div>So my origianl question is not correct, once I set 4 phases, no phase will shrink to empty, and I will get 4 segmentation anyway. (Please correct me if I am wrong).</div>
<div> </div>
<div>Thanks and my best regards</div>
<div> </div>
<div>Baoyun</div>
<div> </div>
<div>Please correct me if I am wrong<br><br>--- On <b>Thu, 3/25/10, Luis Ibanez <i><<a href="mailto:luis.ibanez@kitware.com" target="_blank">luis.ibanez@kitware.com</a>></i></b> wrote:<br></div>
<blockquote style="border-left: 2px solid rgb(16, 16, 255); padding-left: 5px; margin-left: 5px;"><br>From: Luis Ibanez <<a href="mailto:luis.ibanez@kitware.com" target="_blank">luis.ibanez@kitware.com</a>><div class="im">
<br>Subject: Re: [Insight-users] muliple pahse Chan Vese, one partition totally shrink<br>To: "Baoyun Li" <<a href="mailto:baoyun_li123@yahoo.com" target="_blank">baoyun_li123@yahoo.com</a>><br></div>Cc: <a href="mailto:insight-users@itk.org" target="_blank">insight-users@itk.org</a>, "Mosaliganti, Kishore Rao" <<a href="mailto:Kishore_Mosaliganti@hms.harvard.edu" target="_blank">Kishore_Mosaliganti@hms.harvard.edu</a>><br>
Date: Thursday, March 25, 2010, 10:43 PM<div><div></div><div class="h5"><br><br>
<div><br>Hi Baoyun,<br><br><br>You seem to be mixing two different issues here.<br><br>One thing is to segment the image in different regions,<br>and a separate issue is to find an efficient encoding <br>for the resulting segmentations.<br>
<br><br>If you want to segment three different anatomical structures<br>from your image, then you want to use a level set with <br>three phases.<br><br>That is, one phase per object to be segmented.<br><br><br> Regards,<br>
<br><br> Luis<br><br><br>-----------------------------------------------------------------------------<br>
<div class="gmail_quote">On Wed, Mar 24, 2010 at 5:52 PM, Baoyun Li <span dir="ltr"><<a href="http://us.mc1110.mail.yahoo.com/mc/compose?to=baoyun_li123@yahoo.com" rel="nofollow" target="_blank">baoyun_li123@yahoo.com</a>></span> wrote:<br>
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<div>Dear All:</div>
<div> </div>
<div>I have a theoritical question about Chen Vese multiplse pahse leve set.</div>
<div> </div>
<div>I have two level set and the two level set can segment the image to 4 segments, then I can calculate the mean for each segments as following</div>
<div> </div><font size="2">
<div>%c11 = mean (phi1>0 & phi2>0)</div>
<div>%c12 = mean (phi1>0 & phi2<0)</div>
<div>%c21 = mean (phi1<0 & phi2>0)</div>
<div>%c22 = mean (phi1<0 & phi2<0)</div></font>
<div> </div>
<div>How about if I only have three segments, let say segment (phi1<0 & phi2<0) will finally shrink to zeros.</div>
<div> </div>
<div>Then how to I calcuate c22, and also what value of c22 I should use to update leve set equation as shown below:</div>
<div> </div>
<div>((u-c22)^2-(u-c12)^2)H(phi2).</div>
<div> </div>
<div>I saw somebody use the mininum number of the machine to replace c22, but I could not imagine what will happen and why to do that.</div>
<div> </div>
<div>Thanks</div>
<div>Baoyun</div>
<div> </div>
<div> </div>
<div> </div>
<div> </div>
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