<div class="gmail_quote">On Thu, Aug 20, 2009 at 4:28 AM, Balaji, R IN BLR SISL <span dir="ltr"><<a href="mailto:r.balaji@siemens.com">r.balaji@siemens.com</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;"><div link="blue" vlink="purple" lang="EN-US"><div>
<p>Can you please advice on which algo will be suitable and
if possible the reason behind the time taken by the B-Spline algo ?</p></div></div></blockquote><div><br>Balaji:<br>
<br>Yes it is quite time consuming. The following questions will help ameliorate your situation.<br><br>
- What is the resolution of the images ?<br><br>
- On which image is the BSpline grid being defined PET or CT. Choosing the lower resolution image as the fixed image is going to speed up metric evaluation.<br>
<br>- What is the resolution of the grid ? This impacts speed.<br>
<br>- Have you turned ITK_USE_OPTIMIZED_REGISTRATION on ?<br><br>- If the answer to the previous question is yes, did you enable caching of the BSpline transform parameters ? This provides significant speedups. See <a href="http://www.insight-journal.org/browse/publication/172">http://www.insight-journal.org/browse/publication/172</a> for quantitative experiments detailing the speedups.<br>
Depending on the resolution of your data and memory availability on your machine, this may or may not be possible. Memory requirements shoot up with caching.<br><br>- Did you take a look at multiresolution registration options. Take a look at DeformableRegistration15.cxx . This does a coarse and fine deformable registration and uses a BSplineDecomposition filter to initialize the fine BSpline transform from the coarse.<br>
<br>- Did you take a look at rigid followed by deformable registration. Again please look at DeformableRegistration15.cxx .<br><br>- If your registration problem can be localized to a specific region, you could specify a fixed image region and/or fixed and moving image masks. This will restrict the computation of the metric / and / allow you to define a higher resolution transform within the region in question.<br>
<br>Hope this helps.<br> </div></div><br clear="all"><br>-- <br>Karthik Krishnan<br>R&D Engineer,<br>Kitware Inc.<br>Ph: 518 881 4919<br>Fax: 518 371 4573<br>