[ITK-users] Is this a bug in euler 3D transform??

[vishal]

hi,
Im working on a 2d/3d registration algorithm... Im using Euler3dtransform...
the registration doesnt converge  since the 3d volume tends to translate
during the registration process... i have tried these examples
[1]http://www.itk.org/Doxygen/html/SphinxExamples_2src_2Core_2Transform_2CopyANonCompositeTransform_2Code_8cxx-example.html#_a0
[2]http://www.itk.org/Doxygen/html/SphinxExamples_2src_2Core_2Transform_2CopyACompositeTransform_2Code_8cxx-example.html#_a0

in [1] they use TransformType::ParametersType fixedParameters(3); to set the
rotation constant and only allow the volume to translate( this is my
understanding of the code...pls correct me if im wrong) when i applied this
to my code it ISNT working properly.... i was expecting euler parameters to
be [-3.5;-4.5;-5.5;
some-X-axis-translation;some-Yaxis--translation,some-Zaxis--translation];
this doesnt happen...

here is a piece of my code where i attempt to STOP the volume from
translating during registration and only allow the volume to rotate about
the z-axis:-

#if defined(ITK_FIXED_PARAMETERS_ARE_DOUBLE) // After 4.8.1
   TransformType::FixedParametersType fixedParameters(3);
#else                                         //Pre 4.8.1
  TransformType::ParametersType fixedParameters(6);
#endif
  fixedParameters[3] = 0.0;
  fixedParameters[4] = 0.0;
  fixedParameters[5] = 0.0;
  transform->SetFixedParameters( fixedParameters );
  registration->SetInitialTransformParameters( transform->GetParameters() );

i was expecting euler parameters to be [some-X axis-rotation;some-Y
axis-rotation,some-Z axis-rotation,0.0,0.0,0.0]; this doesnt happen...
please advice if this is an error [OR] a wrong implementation [OR] is
disabling translation in euler transform is IMPOSSIBLE? any advice is
appreciated...
Regards
Vishal





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