+ } else if(m_ArgsInfo.transform_grid_flag) {
+ typename itk::Matrix<double, Dimension+1, Dimension+1> invMatrix( matrix.GetInverse() );
+ typename itk::Matrix<double, Dimension, Dimension> invRotMatrix( clitk::GetRotationalPartMatrix(invMatrix) );
+ typename itk::Vector<double,Dimension> invTrans = clitk::GetTranslationPartMatrix(invMatrix);
+
+ // Spacing is influenced by affine transform matrix and input direction
+ typename InputImageType::SpacingType outputSpacing;
+ outputSpacing = invRotMatrix *
+ input->GetDirection() *
+ input->GetSpacing();
+
+ // Origin is influenced by translation but not by input direction
+ typename InputImageType::PointType outputOrigin;
+ outputOrigin = invRotMatrix *
+ input->GetOrigin() +
+ invTrans;
+
+ // Size is influenced by affine transform matrix and input direction
+ // Size is converted to double, transformed and converted back to size type.
+ vnl_vector<double> vnlOutputSize(Dimension);
+ for(unsigned int i=0; i< Dimension; i++) {
+ vnlOutputSize[i] = input->GetLargestPossibleRegion().GetSize()[i];
+ }
+ vnlOutputSize = invRotMatrix *
+ input->GetDirection().GetVnlMatrix() *
+ vnlOutputSize;
+ typename OutputImageType::SizeType outputSize;
+ for(unsigned int i=0; i< Dimension; i++) {
+ // If the size is negative, we have a flip and we must modify
+ // the origin and the spacing accordingly.
+ if(vnlOutputSize[i]<0.) {
+ vnlOutputSize[i] *= -1.;
+ outputOrigin[i] = outputOrigin[i] + outputSpacing[i] * (vnlOutputSize[i]-1);
+ outputSpacing[i] *= -1.;
+ }
+ outputSize[i] = lrint(vnlOutputSize[i]);
+ }
+ resampler->SetSize( outputSize );
+ resampler->SetOutputSpacing( outputSpacing );
+ resampler->SetOutputOrigin( outputOrigin );