<html>
<head>
<style><!--
.hmmessage P
{
margin:0px;
padding:0px
}
body.hmmessage
{
font-size: 10pt;
font-family:Tahoma
}
--></style>
</head>
<body class='hmmessage'>
<br>Thanks for the reply Tom.<br>When I increase the # iterations to say, -i 1000x500x100x50, I am giving 4 multi-resolutions steps.. Is the image scaling factor assumed to be 1/8, 1/4, 1/2 and 1 uniformly for all 3 axes? Can we set different scaling factors for the 3 axes knowing that the out-of-plane resolution is typically worse than the in-plane resolution in a standard clinical image.<br>Can you provide some more details about the utility of the 2 parameters: Deformation field sigma, Update field sigma.<br><br>Thanks again,<br>Ganesh<br><br><font style="" color="#1f497d" face="Verdana">************************************************************************</font><font style="" color="#1f497d" face="Verdana"><br></font><font style="" color="#1f497d" face="Verdana">
"What the mind of man can conceive and believe, It can achieve" - </font><font style="" color="#1f497d" face="Verdana"><span class="ecxil">Napolean</span></font><font style="" color="#1f497d" face="Verdana"> </font><font style="" color="#1f497d" face="Verdana"><span class="ecxil">Hill</span></font><font style="" color="#1f497d" face="Verdana"><br></font><font style="" color="#1f497d" face="Verdana">
-Ganesh
Narayanasamy,Ph.D., PostDoc-University of Kentucky Cancer Center</font><font style="" color="#1f497d" face="Verdana"><br></font><font style="" color="#1f497d" face="Verdana">
</font><font style="" color="#1f497d" face="Verdana">************************************************************************</font><br><br><br><br>> From: tom.vercauteren@m4x.org<br>> Date: Thu, 24 Feb 2011 08:47:01 +0100<br>> Subject: Re: [Insight-users] Demons Registration<br>> To: nganesh76@hotmail.com<br>> CC: insight-users@itk.org<br>> <br>> Hi Ganesh,<br>> <br>> On Wed, Feb 23, 2011 at 19:04, Ganesh Narayanasamy<br>> <nganesh76@hotmail.com> wrote:<br>> ><br>> > When I run DemonsRegistration using the options as given in the command line<br>> > below, I can get a few output files like final image, deformation field etc.<br>> > How would I get the rest of the output like "True field file"?<br>> <br>> The "true field" is an input not an output. It may be used for<br>> synthetic experiments where the actual deformation is known.<br>> DemonsRegistration then compares at each iteration its result against<br>> this ground truth (but of course it does not use it to drive the<br>> registration).<br>> <br>> <br>> > As the image was not deforming enough, I had opted to reduce sigma from the<br>> > default value of 1.5 to 0.8.. is this the correct approach?<br>> <br>> This entirely depends on your use case... That being said, I would<br>> first try to use more iterations and then reduce the sigma.<br>> <br>> <br>> > Size of the fixed and moving images are 384x384x64 pixels each. I would like<br>> > to register using the multi-resolution approach starting with 1/4th number<br>> > of pixels in all 3 axes (i.e, 96x96x16), going to 1/2 (ie., 192x192x32<br>> > pixels) and finally to the full image. How will I do this?<br>> <br>> It is already done, see the number of multiresolution levels and<br>> number of iterations per level:<br>> > Number of multiresolution levels: 3<br>> > Number of demons iterations: [ 15 10 5 ]<br>> <br>> Hope this helps,<br>> Tom<br>> <br>> <br>> > Command:<br>> >>DemonsRegistration.exe -f CBCT1.mha -m CBCT4.mha -o Final.mha -O DefFld.mha<br>> >> -s 0.8 -d 1<br>> ><br>> > Starting demons registration with the following arguments:<br>> > Arguments structure:<br>> > Fixed image file: CBCT1.mha<br>> > Moving image file: CBCT4.mha<br>> > Input field file:<br>> > Input transform file:<br>> > Output image file: Final.mha<br>> > Output field file: DefFld.mha<br>> > True field file:<br>> > Number of multiresolution levels: 3<br>> > Number of demons iterations: [ 15 10 5 ]<br>> > Deformation field sigma: 0.8<br>> > Update field sigma: 0<br>> > Maximum update step length: 2<br>> > Update rule: exponentialize and compose (Diffeomorphic)<br>> > Type of gradient: symmetrized (ESM for diffeomorphic and compositive)<br>> > Use histogram matching: false<br>> > Algorithm verbosity (debug level): 1<br>> ><br>> > Thanks,<br>> > Ganesh<br> </body>
</html>