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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’m not so familiar with the difference of a versor and a quaternion, but I thought, the 4 representing values should be the same in both structures.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>If so, then there might be a bug, when converting a itkVersorRigid3DTransform into a vnl_quaternion (or I’m just doing the conversion in a wrong way).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’m doing the conversion of a <span style='font-size:10.0pt;font-family:"Courier New"'>itk::VersorRigid3DTransform<double>::Pointer transform </span>as follows<span style='font-size:10.0pt;font-family:"Courier New"'>:</span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>vnl_quaternion<<span style='color:blue'>double</span>>(transform->GetMatrix().GetVnlMatrix());<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal>The resulting quaternion does not equal the versor, for example read out with<span style='font-size:10.0pt;font-family:"Courier New"'> ->GetVersor(). </span>From the few examples I tried, it looks as if only the direction of the rotation changes, but rotation axis and angle are the same.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks a lot in advance for your help!<o:p></o:p></p><p class=MsoNormal>Best<o:p></o:p></p><p class=MsoNormal>Anja<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>--------------<o:p></o:p></p><p class=MsoNormal>Dipl.-Inform. Anja Groch<o:p></o:p></p><p class=MsoNormal>German Cancer Research Center (DKFZ)<o:p></o:p></p><p class=MsoNormal>Div. Medical and Biological Informatics<o:p></o:p></p><p class=MsoNormal>Junior Group: Computer-assisted Interventions (E131) <o:p></o:p></p><p class=MsoNormal><span lang=DE>Im Neuenheimer Feld 280<o:p></o:p></span></p><p class=MsoNormal><span lang=DE>69120 Heidelberg, Germany <o:p></o:p></span></p><p class=MsoNormal><span lang=DE><o:p> </o:p></span></p><p class=MsoNormal><span lang=DE>Email: <a href="mailto:a.groch@dkfz.de">a.groch@dkfz.de</a><o:p></o:p></span></p><p class=MsoNormal>Phone: (+49) 6221/42-3548<o:p></o:p></p><p class=MsoNormal>Fax: (+49) 6221/42-2345<o:p></o:p></p><p class=MsoNormal><span lang=DE><a href="http://www.dkfz-heidelberg.de/de/mbi/people/Anja_Groch.html"><span lang=EN-US>http://www.dkfz-heidelberg.de/de/mbi/people/Anja_Groch.html</span></a></span><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p></div></body></html>