<br>Hi Andy,<br><br>Thanks for pointing this out.<br><br>We have struggled in the past with the selection<br>of values to be used as tolerances...<br><br>We tend to put tolerances that are too stringent,<br>and sometimes unrealistic. I recall that recently<br>
Hans Johnson fixed several classes that were<br>using tolerances that were too exigent.<br><br>You may be pointing out to a case that also needs<br>reevaluation.<br><br>Any suggestions on what could be a realistic value,<br>
that is still making sure that we don't take in matrices<br>that are too deformed ?<br><br>Also, another option to consider is that we have code<br>that computes the Orthogonal part of a Matrix that<br>is not fully orthogonal. This is done via Polar decomposition,<br>
<br>See for example<br><a href="http://www.itk.org/pipermail/insight-users/2006-August/019025.html">http://www.itk.org/pipermail/insight-users/2006-August/019025.html</a><br><br>You could use this code for cleaning up that Matrix,<br>
before passing it to the Rigid Transform.<br><br><br>Please let us know what you think is a better approach,<br><br><br> Thanks<br><br><br> Luis<br><br><br>------------------------------------------------------------------------<br>
<div class="gmail_quote">On Thu, Jul 2, 2009 at 11:43 AM, Andriy Fedorov <span dir="ltr"><<a href="mailto:fedorov@bwh.harvard.edu">fedorov@bwh.harvard.edu</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;">
Hi,<br>
<br>
What is the motivation for setting the tolerance in matrix orthogonality<br>
test to 1e-10 in itkRigid3DTransform.cxx?<br>
<br>
I have a transform produced by FSL FLIRT tool, which is orthogonal with<br>
tolerance 1e-5. I am trying to re-shape this transform to an ITK<br>
transform (FSL uses different origin conventions), so that I can import<br>
it into Slicer. With the current tolerance setting this is not possible,<br>
the code breaks when I am trying to set the matrix.<br>
<br>
Is the current check with 1e-10 tolerance level a correct and necessary<br>
precaution? Isn't it too strict for practical purposes?<br>
<br>
Thanks<br>
<br>
Andriy Fedorov<br>
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