Issues about itkTransformixFilter

[yourtheron]

I performed a simple rigid-body registration via elastix C++
`bool ImageRegistration::ElastixAutoRegistration(const std::string regMethod)
{
this->_opMode = 1;
// Remove all pairs of user-specified landmarks, if any.
int p = 0;
int lmCount = this->GetLMCount();
if (lmCount > 0)
{
for (p = 0; p < lmCount; p++) RemoveOnePairLandMarks(p);
}
ImagePointer fixedImage = ImageType::New();
ImagePointer movingImage = ImageType::New();
VTKDataTransformOperation::VTKImageToITK(this->_fixedImage, fixedImage);
if (this->GetRegStatus())
{
VTKDataTransformOperation::VTKImageToITK(this->_regImage, movingImage);
}
else
{
VTKDataTransformOperation::VTKImageToITK(this->_movingImage, movingImage);
}

auto outSize = fixedImage->GetLargestPossibleRegion().GetSize();


auto caster1 = itk::CastImageFilter<ImageType, FloatImageType>::New();
auto caster2 = itk::CastImageFilter<ImageType, FloatImageType>::New();
//auto caster1 = itk::GPUCastImageFilter<ImageType, FloatImageType>::New();
//auto caster2 = itk::GPUCastImageFilter<ImageType, FloatImageType>::New();
FloatImageType::Pointer floatFixedImage = FloatImageType::New();
FloatImageType::Pointer floatMovingImage = FloatImageType::New();
if (regMethod != "bspline")
{
	caster1->SetInput(fixedImage);
	caster1->Update();
	floatFixedImage = caster1->GetOutput();
	caster2->SetInput(movingImage);
	caster2->Update();
	floatMovingImage = caster2->GetOutput();
}
else
{
	int i = 0;
	int j = 0;
	ImageRegionType region;

	// Set the region bounds using the array values
	ImageIndexType start;
	ImageSizeType size;
	for (j = 0; j < 3; j++)
	{
		start[j] = static_cast<ImageIndexType::IndexValueType>(this->_voi[2 * j]);
	}
	for (j = 0; j < 3; j++)
	{
		size[j] = static_cast<ImageSizeType::SizeValueType>(this->_voi[2 * j + 1] - this->_voi[2 * j] + 1);
	}
	region.SetIndex(start);
	region.SetSize(size);

	ImagePointer fixrdROI = ImageType::New();
	fixrdROI = ImProcOperation::extractROI<ImageType>(fixedImage, region);
	ImagePointer movingROI = ImageType::New();
	movingROI = ImProcOperation::extractROI<ImageType>(movingImage, region);

	caster1->SetInput(fixrdROI);
	caster1->Update();
	floatFixedImage = caster1->GetOutput();
	caster2->SetInput(movingROI);
	caster2->Update();
	floatMovingImage = caster2->GetOutput();
}

const auto parameterObject = elx::ParameterObject::New();
auto parameterMap = parameterObject->GetDefaultParameterMap(regMethod.c_str());

parameterMap["MaximumNumberOfIterations"] = { std::to_string(std::max(this->_autoRegIter, 1)) };

// It seems that elastix dictates that both fixed and moving images are of float. Using short or double does not work.
parameterMap["FixedInternalImagePixelType"] = { "float" };
parameterMap["MovingInternalImagePixelType"] = { "float" };
parameterMap["Interpolator"] = { "BSplineInterpolator" };
parameterMap["AutomaticTransformInitialization"] = { "true" };
parameterMap["HowToCombineTransforms"] = { "Compose" };
// Specify whether you want to take into account the so-called direction cosines of the images. Recommended: true.
// In some cases, the direction cosines of the image are corrupt, due to image format conversions for example. In that case, you 
// may want to set this option to "false".
parameterMap["UseDirectionCosines"] = { "false" };
parameterMap["BSplineInterpolationOrder"] = { "1" };
parameterMap["FinalBSplineInterpolationOrder"] = { "3" };
// Setting a large "NumberOfHistogramBins" will worsen the registration result. It might be because two histograms each with a hefty number of bins
// derived from local features are difficult to be matched; or too many lower bins will cause incorrect features to be matched better than authentic ones.
// Simply keep the default value that is 32. 16 is also acceptable.
// parameterMap["NumberOfHistogramBins"] = { "32" };
// parameterMap["ErodeMask"] = { "false" };
// parameterMap["ImagePyramidSchedule"] = { "8", "8", "8", "4", "4", "4", "2", "2", "2", "1", "1", "1" };
// For some unknown reason, setting "WriteResultImage" false will make elastix crash.
// There is currently no way to know where default output directory goes.
// parameterMap["WriteResultImage"] = { "false" };

parameterObject->SetParameterMap(parameterMap);

//std::string filePath = "d:/Standard Test Cases/rigid_registration_parameters.txt";
//char buffer[1024];
//// Current working directory
//_getcwd(buffer, sizeof(buffer));
//// Write parameters to the file
//std::ofstream outFile(filePath);
//if (outFile.is_open()) {
//	outFile << "Current working directory: " << buffer << std::endl;
//	for (const auto &entry : parameterMap) {
//		outFile << entry.first << " = ";
//		for (const auto &value : entry.second) {
//			outFile << value << " ";
//		}
//		outFile << std::endl;
//	}
//	outFile.close();
//	std::cout << "Parameters saved to " << filePath << std::endl;
//}
//else {
//	std::cerr << "Unable to open file for writing." << std::endl;
//}



// Create Elastix main class for registration
const auto filter = itk::ElastixRegistrationMethod<FloatImageType, FloatImageType>::New();
filter->SetFixedImage(floatFixedImage);
filter->SetMovingImage(floatMovingImage);
filter->SetParameterObject(parameterObject);

this->_elRenderer->RemoveActor(this->_elMessage);
if (regMethod == "rigid") this->_elMessage->SetInput("Rigid-body Registration in Process...");
else if (regMethod == "affine") this->_elMessage->SetInput("Affine Registration in Process...");
else this->_elMessage->SetInput("B-spline Registration in Process...");
this->_elRenderer->AddActor(this->_elMessage);

this->_elBorderWindow->Render();
this->_elBorderWindow->Modified();
this->_elWindow->Render();
this->_elWindow->Modified();
filter->Update();
this->_elWindow->Finalize();
this->_elBorderWindow->Finalize();
//LOG(ERROR) << filter->Get
FloatImageType::Pointer outputImage = filter->GetOutput();

//auto caster3 = itk::GPUCastImageFilter<FloatImageType, ImageType>::New();
//auto caster3 = itk::CastImageFilter<FloatImageType, ImageType>::New();
//caster3->SetInput(filter->GetOutput());
//caster3->Update();
//ImageType::Pointer outImage = caster3->GetOutput();

// In order to use GPU-enabled classes in ITK, a regular ITK image must be converted into ITK-GPU image
using GPUImageType = itk::GPUImage<double, 3>;
using GPUImageTypeOut = itk::GPUImage<double, 3>;
// Set up the cast filter to convert the regular image to a GPU image
auto castFilter = itk::CastImageFilter<FloatImageType, GPUImageType>::New();
castFilter->SetInput(outputImage);
castFilter->Update();

auto caster3 = itk::GPUCastImageFilter<GPUImageType, GPUImageTypeOut>::New();
caster3->SetInput(castFilter->GetOutput());
caster3->Update();
GPUImageTypeOut::Pointer outImage = caster3->GetOutput();

auto castFilter1 = itk::CastImageFilter<GPUImageTypeOut, ImageType>::New();
castFilter1->SetInput(caster3->GetOutput());
castFilter1->Update();

VTKDataTransformOperation::ITKImageToVTK<ImageType>(castFilter1->GetOutput(), this->_regImage);
//VTKDataTransformOperation::outputVTKImageFile(this->_regImage, "D:/Standard Test Cases/AfterReg.mhd");

// It seems itk::TransformixFilter<FloatImageType> cannot be instantiate, which renders it impossible to utilise
// elastix to apply the same registration parameter to another image
itk::TransformixFilter<FloatImageType>::Pointer transformixFilter = itk::TransformixFilter<FloatImageType>::New();
transformixFilter->SetMovingImage(newMovingImage);
transformixFilter->SetTransformParameterObject(filter->GetTransformParameterObject()); // or load from file
transformixFilter->Update();
auto caster4 = itk::CastImageFilter<FloatImageType, ImageType>::New();
caster4->SetInput(transformixFilter->GetOutput());
caster4->Update();
VTKDataTransformOperation::ITKImageToVTK<ImageType>(caster4->GetOutput(), this->_regImage);
VTKDataTransformOperation::outputVTKImageFile(this->_regImage, "D:/Standard Test Cases/AfterReg1.mhd");


this->_globalReged = true;

return true;

}`
Then, I wish to use itk::TransformixFilter to apply the same registration parameter to a newMovingImage. And yet no matter how I declare and define itk::TransformixFilter::Pointer transformixFilter = itk::TransformixFilter::New();, the compiler says something like it is an abstract object that cannot be instantiated. Could you help me figure out why? Or is it already a known issue? Many thanks.