[Insight-users] Inverse transform problem of given parameters

[Fucang Jia]

Hi, everyone,

I want to use inverse transform of ITK registration result recently. So I want to use the convenient GetInverse method to get the inverse transform. When I give the transform parameters,
the GetInverse seems not occurs, which is at line 260th in itkMatrixOffsetTransformBase.txx version 1.10:
if(m_InverseMatrixMTime != m_MatrixMTime)

Should I add some code to enforce it compute? Thank you very much!

Fucang


=============================================================


#if defined(_MSC_VER)
#pragma warning ( disable : 4786 )
#endif

#include <iostream>
#include "itkMatrix.h"
#include "itkAffineTransform.h"


int main(int argc, char *argv[] ) 
{
	
	double transformmatrix[12];
	
	transformmatrix[0] = 0.999797;
	transformmatrix[1] = -0.00583563;
	transformmatrix[2] = -0.0192842l;
	transformmatrix[3] = 0.00591944;
	transformmatrix[4] = 0.999973;
	transformmatrix[5] = 0.00429143;
	transformmatrix[6] = 0.0192587;
	transformmatrix[7] = -0.00440471;
	transformmatrix[8] = 0.999805;
	transformmatrix[9] = -0.690118;
	transformmatrix[10] = -0.823229;
	transformmatrix[11] = -15.285;
	
	
	// matrix inverse method
	
	typedef   double                                NumericType;
	typedef   itk::Matrix<NumericType,4,4>          MatrixType;
	MatrixType matrix;
	matrix.Fill( 0.0 );
	
	
	matrix[0][0] = transformmatrix[0];
	matrix[0][1] = transformmatrix[1];
	matrix[0][2] = transformmatrix[2];
	
	matrix[1][0] = transformmatrix[3];
	matrix[1][1] = transformmatrix[4];
	matrix[1][2] = transformmatrix[5];
	
	matrix[2][0] = transformmatrix[6];
	matrix[2][1] = transformmatrix[7];
	matrix[2][2] = transformmatrix[8];
	
	matrix[0][3] = transformmatrix[9];
	matrix[1][3] = transformmatrix[10];
	matrix[2][3] = transformmatrix[11];
	
	matrix[3][3] = 1.0;
	
	
	vnl_matrix_fixed<double,4,4>  invmatrix = matrix.GetInverse();
	
	std::cout<<"vnl inverse method: "<<std::endl;
	std::cout<<invmatrix<<std::endl;
	
	
	// affine transform inverse method
	
    typedef itk::AffineTransform<double, 3> AffineTransformType;
	AffineTransformType::Pointer paff = AffineTransformType::New();	
	AffineTransformType::Pointer inv = AffineTransformType::New();
	
	AffineTransformType::ParametersType parameters(paff->GetNumberOfParameters());
	
	for(int i=0;i<12;i++)
		parameters[i] = transformmatrix[i];
	
	paff->SetParameters(parameters);
	
	paff->GetInverse(inv);
	
    inv->Print(std::cout);
	
	std::cout<<"affine transform inverse method: "<<std::endl;
	
	std::cout<<inv->GetParameters()<<std::endl;
	
	
	
    return 0;
}

The experiment is as follows:

vnl inverse method:
0.999797 0.00591943 0.0192586 0.989219
-0.00583564 0.999974 -0.00440471 0.751854
-0.0192843 0.00429143 0.999805 15.2722
-2.60209e-018 -2.86229e-017 4.16334e-017 1

AffineTransform (00372CF0)
  RTTI typeinfo:   class itk::AffineTransform<double,3>
  Reference Count: 1
  Modified Time: 3
  Debug: Off
  Observers:
    none
  Matrix:
    1 0 0
    0 1 0
    0 0 1
  Offset: [0.690118, 0.823229, 15.285]
  Center: [0, 0, 0]
  Translation: [0.690118, 0.823229, 15.285]
  Inverse:
    0.999797 -0.00583563 -0.0192842
    0.00591944 0.999973 0.00429143
    0.0192587 -0.00440471 0.999805
  Singular: 0
affine transform inverse method:
[1, 0, 0, 0, 1, 0, 0, 0, 1, 0.690118, 0.823229, 15.285]