<div dir="ltr">Hi,<div>For my project I ended up using a diffusion based algorithm somewhat similar to described in <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.87.6924&rep=rep1&type=pdf">http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.87.6924&rep=rep1&type=pdf</a></div><div><br></div><div>Here is a summary of the algorithm ( section 4 in paper above ) :</div><div><br></div><div><i>A time and space discretized solution the the geometry-constrained diffusion
may be obtained by iterative Gaussian convolution and back-projecting the constrained
surfaces.
The crux of the algorithm then becomes : </i></div><div><i>1. Initial displacement. Construct an initial guess of the displacement field. </i></div><div><i>2. Diffusion step. Convolve the displacement field with a Gaussian kernel. </i></div><div><i>3. Deform source. Deform the source surface with respect to the displacement
field. </i></div><div><i>4. Matching (Projection onto the target surface). For all points on the
deformed surface: Find the closest point on the target surface. </i></div><div><i>5. Update displacement field. For all points on the deformed surface: Change
the displacements according to the match. </i></div><div><i>6. Convergence. Is the displacement field stable? If not, go to 2.
Some of the steps are explained in greater detail below</i><br></div><div><br></div><div>I also used the features ( curvature in step 4) to determine the closeness. The algorithm took a surface model and a point set as input. The vertices of the surface model were deformed to match the point set without modifying the connectivity.</div><div><br></div><div>Thanks,</div><div>Somi</div><div><br></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature"><div><font color="#FF0000" face="'Helvetica Neue', Arial, Helvetica, sans-serif" size="3"><span style="font-size:11px;line-height:16px"><span style="color:rgb(0,0,0);font-family:arial,sans-serif;line-height:normal;font-size:13px;border-collapse:collapse"><div><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;line-height:16px"><font color="#FF0000">C</font></span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;color:rgb(153,153,153);line-height:16px">onfessions, </span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;line-height:16px"><font color="#FF0000">O</font></span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;color:rgb(153,153,153);line-height:16px">bsessions , </span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;line-height:16px"><font color="#FF0000">B</font></span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;color:rgb(153,153,153);line-height:16px">eliefs , </span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;line-height:16px"><font color="#FF0000">W</font></span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;color:rgb(153,153,153);line-height:16px">ishes , and a few </span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;line-height:16px"><font color="#FF0000">E</font></span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;color:rgb(153,153,153);line-height:16px">soteric </span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;line-height:16px"><font color="#FF0000">B</font></span><span style="font-family:'Helvetica Neue',Arial,Helvetica,sans-serif;font-size:11px;color:rgb(153,153,153);line-height:16px">logs</span></div><span style="font-size:x-small"><a href="http://500px.com/seesomi" style="color:rgb(6,88,181)" target="_blank">http://500px.com/seesomi</a></span></span></span></font></div></div></div>
<br><div class="gmail_quote">On Mon, Apr 27, 2015 at 12:32 PM, brian avants <span dir="ltr"><<a href="mailto:stnava@gmail.com" target="_blank">stnava@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:monospace,monospace;color:#351c75">hi michel</div><div class="gmail_default" style="font-family:monospace,monospace;color:#351c75"><br></div><div class="gmail_default" style="font-family:monospace,monospace;color:#351c75">nick tustison did some good work on this recently and most of it is available in both ITK and in ANTs. the work is evolving (in terms of efficient memory use) but the basics of doing images + segmentations/surfaces is available. e.g. you could run a demons + iterative closest point registration pretty easily.</div></div><div class="gmail_extra"><br clear="all"><div><div><br>brian<br><br></div></div>
<br><div class="gmail_quote"><div><div class="h5">On Mon, Apr 27, 2015 at 12:12 PM, Audette, Michel A. <span dir="ltr"><<a href="mailto:maudette@odu.edu" target="_blank">maudette@odu.edu</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
<div>
<div style="direction:ltr;font-family:Tahoma;color:#000000;font-size:10pt">
<p>Dear ITK users, </p>
<p> </p>
<p>one of my students needs to produce an accurate surface mesh correspondence in conjunction with stats shape aware active surface models, towards a vertebral segmentation application.
</p>
<p> </p>
<p>Doing a Google search on this, I found a discussion from 2009 <a href="http://public.kitware.com/pipermail/insight-users/2009-August/031857.html" target="_blank">
http://public.kitware.com/pipermail/insight-users/2009-August/031857.html</a>; I was wondering if there has been progress in this area since then. For example, can the image deformation methods such as Demons and the like be applied to a surface to surface
correspondence problem (with further information available such as underlying MRI gradients)? </p>
<p> </p>
<p>Our surface meshes relate to vertebral surfaces, so these are not topologically equivalent to spheres; they are more like doughnuts.
</p>
<p> </p>
<p>Thanks for kind support. </p>
<p> </p>
<p>Michel</p>
<div>
<p> </p>
<div><font size="2" face="Tahoma">Michel Audette, Ph.D. </font></div>
<div><font size="2" face="tahoma">Assistant Professor,</font></div>
<div><font size="2" face="tahoma">Department of Modeling, Simulation and Visualization Engineering,</font></div>
<div><font size="2" face="tahoma">Old Dominion University,</font></div>
<div><font size="2" face="Tahoma">Norfolk, VA.</font></div>
<div><font size="2" face="tahoma"></font> </div>
</div>
</div>
</div>
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