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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Hi Brad,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>Thank you very much for
your reply. I tried to use the ExhaustiveOptimizer, but it did not iterate over
my first parameter. Is there some bug in the ExhaustiveOptimizer? I found on
the Kitware public wiki-page “ITK Adopt A Bug Program” an entry for
the ExhaustiveOptimizer. What is the bug mentioned there about? Thank you in
advance.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>Cheers<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>Sven<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span lang=EN-GB
style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>Von:</span></font></b><font
size=2 face=Tahoma><span lang=EN-GB style='font-size:10.0pt;font-family:Tahoma'>
Bradley Lowekamp [mailto:blowekamp@mail.nih.gov] <br>
<b><span style='font-weight:bold'>Gesendet:</span></b> Dienstag, 16. September
2</span></font><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma'>008 17:55<br>
<b><span style='font-weight:bold'>An:</span></b> Fischer, Sven<br>
<b><span style='font-weight:bold'>Betreff:</span></b> Re: [Insight-users]
Optimization problem</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hello,<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>I know it's not the fastest, but I have found using
the ExhaustiveOptimizer at the coarsest resolution can be useful of
finding a good starting point. If you are able to get the right resolution (or
coarse feature) and the right grid size it should give you
a reasonable starting place for iterative methods.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Brad<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Sep 16, 2008, at 5:26 AM, Fischer, Sven wrote:<o:p></o:p></span></font></p>
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12.0pt'><br>
<br>
<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Hi all,<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'><u1:p> </u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:black'>I’m doing a 2D 3D
registration between fluoroscopic images and CT images, creating a DRR. Since I
have several local optima I use a multi resolution approach. I scale the images
by a factor of two and do Gaussian blurring. So I scale in 4 steps. First I register
the images with one eighth of the original size, than with one fourth, with the
half size and finally with the original size. But I have local optima in the
first step. So it leads me to misregistration when my starting point is too far
away from the final point when my images are correct registered. I can avoid
this problem with using a different step size for the Powell optimizer. But
when I find a good step size for one starting point it often is useless for
other starting points.<u1:p></u1:p></span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:black'>My images are cardiac
images, where the aorta and the spine can be seen very clearly. I use the
Gradient Difference Metric ( not exactly the ITK-Implementation, I changed it a
bit, and it worked very well in several tests ).<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:black'>Do you have an idea how
I could find good starting points or how to choose the step size for the
Optimizer, depending on the information the image gives me? Or should I use
another Optimizer? What is your experience? I’m looking forward to your
answers.<u1:p></u1:p></span></font><font color=black><span style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:black'><u1:p> </u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:black'>Regards<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:black'>Sven<u1:p></u1:p></span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=1 color=black face=Helvetica><span
style='font-size:9.0pt;font-family:Helvetica;color:black'>_______________________________________________<br>
Insight-users mailing list<br>
<a href="mailto:Insight-users@itk.org">Insight-users@itk.org</a><br>
<a href="http://www.itk.org/mailman/listinfo/insight-users">http://www.itk.org/mailman/listinfo/insight-users</a><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'></span><o:p> </o:p></span></font></p>
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<p style='margin:0cm;margin-bottom:.0001pt'><font size=1 color=black
face=Helvetica><span style='font-size:9.0pt;font-family:Helvetica;color:black'>========================================================<o:p></o:p></span></font></p>
<p style='margin:0cm;margin-bottom:.0001pt'><font size=1 color=black
face=Helvetica><span style='font-size:9.0pt;font-family:Helvetica;color:black'>Bradley
Lowekamp<span class=apple-converted-space> </span><o:p></o:p></span></font></p>
<p style='margin:0cm;margin-bottom:.0001pt'><span class=apple-style-span><font
size=1 color=black face=Arial><span style='font-size:9.0pt;font-family:Arial;
color:black'>Lockheed Martin </span></font></span><font size=1
color=black face=Helvetica><span style='font-size:9.0pt;font-family:Helvetica;
color:black'>Contractor for<o:p></o:p></span></font></p>
<p style='margin:0cm;margin-bottom:.0001pt'><font size=1 color=black
face=Helvetica><span style='font-size:9.0pt;font-family:Helvetica;color:black'>Office
of High Performance Computing and Communications<o:p></o:p></span></font></p>
<p style='margin:0cm;margin-bottom:.0001pt'><font size=1 color=black
face=Helvetica><span style='font-size:9.0pt;font-family:Helvetica;color:black'>National
Library of Medicine<span class=apple-converted-space> </span><o:p></o:p></span></font></p>
<p style='margin:0cm;margin-bottom:.0001pt'><font size=1 color=black
face=Helvetica><span style='font-size:9.0pt;font-family:Helvetica;color:black'><a
href="mailto:blowekamp@mail.nih.gov">blowekamp@mail.nih.gov</a><o:p></o:p></span></font></p>
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style='font-size:9.0pt;font-family:Helvetica;color:black'><br>
<br>
<o:p></o:p></span></font></p>
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