[Insight-users] Euler3DTransform, Rotation Matrix & Initial Parameters - Continued

[Julien Jomier]

Hi Neilson,

I think it's because your rotation matrix is not orthogonal. You can verify
this by putting a try/catch around the SetRotationMatrix().
SetRotationMatrix() is throwing an exception if the matrix is not
orthogonal.

hope this helps,

Julien

> -----Original Message-----
> From: insight-users-bounces at itk.org 
> [mailto:insight-users-bounces at itk.org] On Behalf Of N.E. 
> Mackenzie Mackay
> Sent: Thursday, July 15, 2004 4:21 PM
> To: Luis Ibanez
> Cc: insight-users at itk.org
> Subject: Re: [Insight-users] Euler3DTransform,Rotation Matrix 
> & Initial Parameters - Continued
> 
> 
> Hey Luis,
> 
> 	Thanks for the help.
> 
> 	I tried implementing the code that you sent.  It 
> compiles and builds  
> fine but am having some difficulty at runtime.  It seems to 
> be crashing  
> when I "SetRotationMatrix".  I am not sure why.  Here is a 
> snapshot of  
> my code:
> 
> 	  TransformType::Pointer transform = TransformType::New();
> 
> 	  TransformType::OffsetType initialTranslation =  
> transform->GetOffset() ;
> 
> 	  initialTranslation[0] = 22.1413;
> 	  initialTranslation[1] = 162.527;
> 	  initialTranslation[2] = 49.913;
> 
> 	  transform->SetOffset(initialTranslation);
> 
> 	  typedef itk::Matrix<double,3,3> MatrixtType ;
> 	  MatrixtType initialRotation;
> 
> 	  initialRotation[0][0] = -0.016292; 
> initialRotation[0][1] = 0.098948;  
> initialRotation[0][2] = 0.0;
> 	  initialRotation[1][0] = 
> 0.00418400;initialRotation[1][1] = 0.007931;  
> initialRotation[1][2] = 0.0;
> 	  initialRotation[2][0] = -0.095128; initialRotation[2][1] =  
> -0.008306;initialRotation[2][2] = 0.0;
> 
> 	transform2->SetRotationMatrix(initialRotation);// 
> crashes on this line
> 	transform2->SetOffset(initialTranslation);
> 
> 	TransformType::ParametersType initialParameters =  
> transform->GetParameters() ;
> 
> 	registration->SetInitialTransformParameters(initialParameters);
> 
> Thanks for the help,
> Neilson
> 
> On Jul 14, 2004, at 1:21 PM, Luis Ibanez wrote:
> 
> >
> > Hi Neilson,
> >
> > The class Euler3DTransform has a method for converting
> > a 3X3 rotation matrix into the 3 rotaion angles.
> > Note that from your 4x4 matrix, only the upper left
> > 3x3 submatrix contains information about rotations.
> >
> > http://www.itk.org/Insight/Doxygen/html/ 
> > classitk_1_1Euler3DTransform.html
> >
> > it is the method
> >
> >    ComputeAnglesFromMatrix()
> >
> > This is a protected method because you don't really need
> > to use it. But if you are curious about the implementation
> > you may want to take a look at the .txx file.
> >
> >
> > Note also that you don't need to do this angle computation
> > since you can initialize the transform with the 3X3 rotation
> > matrix and a translation, then call  GetParamters() on the
> > transform, and finally pass that array of parameters to the
> > ImageRegistrationMethod.
> >
> >
> > The code will look like:
> >
> >
> >    MatrixType rotation = Extract3by3MatrixFromYours();
> >    OffsetType translat = Extract3VectorFromYours();
> >
> >    euler3DTransform->SetRotationMatrix( rotation );
> >    euler3DTransform->SetOffset( translat );
> >
> >    TransformType::ParametersType parameters =
> >                         euler3DTransform->GetParameters();
> >
> >
> >    registrationMethod->SetInitialParameters( parameters );
> >
> >
> >
> >
> >
> > Please let us know if you have further questions
> >
> >
> >
> >   Thanks,
> >
> >
> >
> >      Luis
> >
> >
> >
> > -------------------------------
> > N.E. Mackenzie Mackay wrote:
> >
> >> I am trying to initialize Euler3DTransform in order to perform a  
> >> rigid  registration.  I have a rotation matrix that I wish 
> to use to   
> >> initialize the transformation.  After reading   
> >> http://public.kitware.com/pipermail/insight-users/2003-November/  
> >> 005506.html it looks like this is impossible, the only way to   
> >> initialize the transformation is to set angles and translation   
> >> explicitly.
> >> If this is the case I was wondering if anyone knew a way 
> to extract  
> >> the  3 angles from a 4x4 homogenous matrix?
> >> Thanks
> >> Neilson
> >> _______________________________________________
> >> Insight-users mailing list
> >> Insight-users at itk.org
> >> http://www.itk.org/mailman/listinfo/insight-users
> >
> >
> >
> 
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