<div>David, Brian,</div><div><br></div>We had a discussion a while back about the difference between a <div><br></div><div>transform and a warping, <div><br></div><div><a href="http://www.itk.org/pipermail/insight-users/2011-May/041192.html">http://www.itk.org/pipermail/insight-users/2011-May/041192.html</a></div>
<div><br></div><div><a href="http://www.itk.org/pipermail/insight-users/2011-May/041192.html"></a>my understanding is that theoretically transforms map elements </div><div><br></div><div>from the source space to a target space but a warping maps elements </div>
<div><br></div><div>from the target space to the source space (in most cases).</div><div><br></div><div>This will result in some practical differences between the two, transforms </div><div><br></div><div>will be more complicated since the properties of the input and output </div>
<div><br></div><div>space are quite likely to have major differences, it seems that the purpose </div><div><br></div><div>of the WarpImageFilter was to make things simpler (?!!), however</div><div><br></div><div>using the DeformationFieldTransform might result in more flexibility.</div>
<div><br></div><div>It all depends on how the DeformationFieldTransform is implemented.</div><div><br></div><div>ITK-wise as you can see in,</div><div><br></div><div><a href="http://www.itk.org/Doxygen/html/classitk_1_1DeformationFieldTransform.html">http://www.itk.org/Doxygen/html/classitk_1_1DeformationFieldTransform.html</a></div>
<div><br></div><div>and</div><div><br></div><div><a href="http://www.itk.org/Doxygen/html/classitk_1_1WarpImageFilter.html">http://www.itk.org/Doxygen/html/classitk_1_1WarpImageFilter.html</a></div><div><br></div><div>the DeformationFieldTransform supports most common properties </div>
<div><br></div><div>of other transform filters (although one wonders, could it be used in a</div><div><br></div><div>registration scenario just like other transforms?!!) and all the</div><div><br></div><div>WarpImageFilter does is using the deformation field to back-map the</div>
<div><br></div><div>pixles.</div><div><br></div><div>Did you see any differences in the output image of either filters?</div><div><br></div><div>Dawood</div><div><br></div><div><br></div><div><br></div><div><br></div><div>
<div class="gmail_quote">On Tue, Jul 5, 2011 at 9:59 PM, David Doria <span dir="ltr"><<a href="mailto:daviddoria@gmail.com">daviddoria@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 class="im">On Tue, Jul 5, 2011 at 8:42 AM, Dawood Al Masslawi <<a href="mailto:masslawi@gmail.com">masslawi@gmail.com</a>> wrote:<br>
> Hi David,<br>
> There are 3 code samples of the ICP method in the "/Registration"<br>
> directory of the ITK examples.<br>
> The following article in the Insight Journal also has a simple example<br>
> on how do do landmark registration using the kernel transforms,<br>
> <a href="http://hdl.handle.net/1926/494" target="_blank">http://hdl.handle.net/1926/494</a><br>
> Best regards,<br>
> Dawood<br>
<br>
</div>Could you explain the difference between WarpImageFilter and<br>
DeformationFieldTransform ?<br>
<br>
These seem to do the same thing:<br>
<a href="http://www.itk.org/Wiki/ITK/Examples/Registration/WarpImageFilter" target="_blank">http://www.itk.org/Wiki/ITK/Examples/Registration/WarpImageFilter</a><br>
<a href="http://www.itk.org/Wiki/ITK/Examples/Registration/DeformationFieldTransform" target="_blank">http://www.itk.org/Wiki/ITK/Examples/Registration/DeformationFieldTransform</a><br>
<font color="#888888"><br>
David<br>
</font></blockquote></div><br></div></div>