There are a couple of approaches to constructing your higher <br>order spline coeffs from the lower order ones.<br><br>-----<br><br>The example you are looking at approximates the spline coeffs <br>at the lower order by :<br>
<br>- Upsampling your BSpline coefficient image using some <br> interpolation function to a higher order.<br>
- Decomposing the resulting image, so as to construct Bspline coeffs<br><br>----<br><br>I think you could also just upsample the coefficient image directly as <br>an approximation, using say linear interpolation. There would be a <br>
finite error in the envelope of the resulting spline, as compared to<br>the envelope at the coarser resolution spline but it would not be<br>too much.<br><br>---<br><br>Alternatively, you could also try the contribution from Nick Tustison. <br>
This is an implementation of Lee's paper in N Dimensions and for <br>N order splines. It can take the image of Bspline control points at <br>the lower resolution and upsample it by a factor of 2. The resulting <br>spline will (I think, not sure) have the same envelope as the spline at <br>
the lower resolution. <br><br>This can be found at :<br> <a href="http://www.insight-journal.org/browse/publication/57">http://www.insight-journal.org/browse/publication/57</a><br><br>The classes are in ITK's review directory.<br>
<br><br>--<br>karthik<br><br><br><div class="gmail_quote">On Mon, Jan 12, 2009 at 12:22 PM, Benhacene Boudan Mustafa <span dir="ltr"><<a href="mailto:m.benhacene.boudan@umontreal.ca" target="_blank">m.benhacene.boudan@umontreal.ca</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;"><br>
<br>
Hi all,<br>
i am using a 3 levels multi resolution Bspline algorithm. I would like to smooth the deformation field obtained from the bspline coefficients and then to transform it back to bspline coefficients for the next resolution.<br>
<br>
I am able to transform the bspline coefficients to a dense deformation field and then to smooth the field, but i have a problem obtaining the bspline coefficients from the deformation field. I thought i could use the example "DeformableRegistration6.cxx" (lines 325 to 362) but i couldn't make it works.<br>
<br>
Anyone can point me to the right direction?<br>
<br>
thank you<br>
<br>
karim<br>
<br>_______________________________________________<br>
Insight-users mailing list<br>
<a href="mailto:Insight-users@itk.org" target="_blank">Insight-users@itk.org</a><br>
<a href="http://www.itk.org/mailman/listinfo/insight-users" target="_blank">http://www.itk.org/mailman/listinfo/insight-users</a><br>
<br></blockquote></div><br><br clear="all"><br>-- <br>Karthik Krishnan<br>R&D Engineer,<br>Kitware Inc.<br>Ph: 518 371 3971 x119<br>Fax: 518 371 3971<br>