David,<br><br>Yes, there are differences between the Similarity and Affine Transforms.<br><br>The Similarity Transform does: Translation, Rotation and Uniform Scaling<br><br>The Similarity Transform does *not* do Shearing, and it can not do <br>
non Uniform scaling (e.g. scale X by 5 and scale Y by 7 ).<br><br><br> Luis<br><br><br>--------------------------------------------------------------------------------------------------<br><div class="gmail_quote">On Tue, Jul 14, 2009 at 12:33 PM, Manuel David Tabas Calle <span dir="ltr"><<a href="mailto:manueldavid.tabas@hotmail.es">manueldavid.tabas@hotmail.es</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>
<br>
and what about Similarity2dTransform and AffineTransform??<br>
<br>
what are teh differences??<br><br>
Thanks!<br>
<br>
<hr>
Date: Tue, 14 Jul 2009 12:02:21 -0400<br>From: <a href="mailto:luis.ibanez@kitware.com" target="_blank">luis.ibanez@kitware.com</a><br>To: <a href="mailto:mort.motes@gmail.com" target="_blank">mort.motes@gmail.com</a><br>
CC: <a href="mailto:insight-users@itk.org" target="_blank">insight-users@itk.org</a><br>Subject: Re: [Insight-users] RigidTransform vs AffineTransform?<div><div></div><div class="h5"><br><br><br><br>Hi Motes:<br><br><br> A Rigid Transforms is not<br>
just an Affine centered Transform.<br><br><br>1) A Rigid Transform supports:<br> Translations and Rotations<br><br>2) An Affine Transform supports:<br> Translations, Rotations, Scaling and Shearing.<br>
<br><br>In ITK, both the Rigid and Affine transforms are "centered".<br>Which means that you can specify what point of space should<br>be used as the center of rotations.<br><br><br>Yes, there is something unique that is accomplished by using<br>
a Rigid Transform:<br><br><br> Managing Translations and Rotations, by only optimizing<br> in an space of Six dimensions, instead of the space of <br> 12 dimensions where you have to optimize an Affine Transform.<br> (this for the case of 3D images).<br>
<br><br><br> Regards,<br><br><br> Luis<br><br><br>--------------------------------------------------------------------------------------------<br>
<div>On Sun, Jul 12, 2009 at 3:14 PM, motes motes <span dir="ltr"><<a href="mailto:mort.motes@gmail.com" target="_blank">mort.motes@gmail.com</a>></span> wrote:<br>
<blockquote style="padding-left: 1ex;">In the itkSoftwareGuide an examples is walked through using a RigidTransform. But is a RigidTransform not just a centered AffineTransform? I am a bit confused that a RigidTransform exists, as I understand rigid and non-rigid are concepts that includes transforms. Something like:<br>
<br>Rigid:<br> - Translation<br> - Affine<br><br>Non-Rigid<br> - BsplineDeformableTransform<br><br><br>Or are there something unique about a RigidTransform that is not accomplished using eg. translation or Affine transforms?<br>
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