<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 14 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:10.0pt;
margin-left:.5in;
mso-add-space:auto;
line-height:115%;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
p.MsoListParagraphCxSpFirst, li.MsoListParagraphCxSpFirst, div.MsoListParagraphCxSpFirst
{mso-style-priority:34;
mso-style-type:export-only;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
mso-add-space:auto;
line-height:115%;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
p.MsoListParagraphCxSpMiddle, li.MsoListParagraphCxSpMiddle, div.MsoListParagraphCxSpMiddle
{mso-style-priority:34;
mso-style-type:export-only;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
mso-add-space:auto;
line-height:115%;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
p.MsoListParagraphCxSpLast, li.MsoListParagraphCxSpLast, div.MsoListParagraphCxSpLast
{mso-style-priority:34;
mso-style-type:export-only;
margin-top:0in;
margin-right:0in;
margin-bottom:10.0pt;
margin-left:.5in;
mso-add-space:auto;
line-height:115%;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:1523931523;
mso-list-type:hybrid;
mso-list-template-ids:1775764318 -1102311856 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l0:level1
{mso-level-number-format:roman-lower;
mso-level-text:"%1\)";
mso-level-tab-stop:none;
mso-level-number-position:left;
margin-left:.75in;
text-indent:-.5in;}
@list l0:level2
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level3
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l0:level4
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level5
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level6
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
@list l0:level7
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level8
{mso-level-number-format:alpha-lower;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level9
{mso-level-number-format:roman-lower;
mso-level-tab-stop:none;
mso-level-number-position:right;
text-indent:-9.0pt;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal">Dear ITK community, <o:p></o:p></p>
<p class="MsoNormal">I recently started to use the new framework ITK provides for Level Sets (LevelSetsv4). It seems to be a pretty nice framework and an ideal way to combine different terms from Level Sets theory (advection terms, curvature-based terms, propagation
terms, etc). However, I’m still a bit confused about how to use and configure it.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would really appreciate if anyone of you could help me to clarify any of these questions.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraphCxSpFirst" style="margin-left:.75in;mso-add-space:auto;text-indent:-.5in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">i)<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Looking into the description of these terms, for instance the curvature term: ‘LevelSetEquationCurvatureTerm’ (though this is this is also valid for any other term such as the advection term ‘LevelSetEquationAdvectionTerm’, or the propagation
term ‘LevelSetEquationPropagationTerm’), it seems like the user has the option to define a specific curvature image (according to the literature, this terms is typically defined as an the result of using any edge detector to the image we are trying to segment.
If no curvature image is set, it casts the input image and uses it in the term contribution calculation. My question is how does ITK calculate this term actually. Does it use any edge detector over the input image (such as 1/(1 + G(I)), where I is the input
image, and G(.) is the Gaussian filter)?<o:p></o:p></p>
<p class="MsoListParagraphCxSpMiddle" style="margin-left:.75in;mso-add-space:auto">
What happened if both, the input image and the curvature image are defined? Does ITK ignore the first one?
<o:p></o:p></p>
<p class="MsoListParagraphCxSpMiddle" style="margin-left:.75in;mso-add-space:auto">
<o:p> </o:p></p>
<p class="MsoListParagraphCxSpLast" style="margin-left:.75in;mso-add-space:auto;text-indent:-.5in;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">ii)<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>The second question is about how to control the propagation direction of the level set. In the example, the level set is initialized as a big square area that contains all the elements to segment. In this scenario, the evolution of the
level set should be inward. What if we initialize the level set inside the target structure? In this case the evolution of the level set should be outward. How can we control it? My guess was that the sign of the coefficients that define the weight of each
term would control it, but after making different test, I’m not completely sure about it.<o:p></o:p></p>
<p class="MsoNormal">Thank you very much in advance.<o:p></o:p></p>
<p class="MsoNormal">Juan<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><span style="background:white">Juan J. Cerrolaza PhD<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="background:white"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;background:white">Sheikh Zayed Institute for Pediatric Surgical Innovation</span></b><b><o:p></o:p></b></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;background:white">Children's National Health System</span></b><span style="font-size:10.0pt"><br>
<i><span style="background:white">111 Michigan Avenue, NW</span><br>
<span style="background:white">Washington, DC 20010</span></i><b><span style="background:white"><o:p></o:p></span></b></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#500050"><br>
</span><span style="font-size:10.0pt;background:white">E-mail:<span style="color:#500050"> </span><a href="mailto:JCerrola@cnmc.org"><span style="color:blue">JCerrola@cnmc.org</span></a><span style="color:#500050">,
<a href="mailto:jjcerromar@gmail.com"><span style="color:blue">jjcerromar@gmail.com</span></a></span><b><o:p></o:p></b></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt">Phone:<span style="color:#1F497D">
</span><a href="tel:%2B1-202-476-3059" target="_blank"><span style="color:windowtext;text-decoration:none">+1</span></a> (202) 476-1272<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><i><span style="font-size:10.0pt">We stand for children.<o:p></o:p></span></i></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;color:#1F497D"><a href="http://www.ChildrensNational.org"><span style="color:blue">www.ChildrensNational.org</span></a><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;color:#222222"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<HR>Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.<BR>
</body>
</html>