VTK学习笔记（四十）vtk提取单层数据

1. VTK学习笔记（四十）vtk提取单层数据

VTK实现单层图片的提取方法有很多，可以使用的filter有很多。

1. 最底层的方法是获取图像指针，逐体素创建一个单层图像；
2. vtkExtractVOI提取单层图像；
3. vtkConstantPad提取单层图像；
4. vtkImageReslice提取单层图像；

1.1 vtkImageReslice提取单层图像

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

int main(int, char*[])
{
    string fileName = "test.nii.gz";
    vtkSmartPointer<vtkImageData> input;
    vtkSmartPointer <vtkNIFTIImageReader> niftireader = vtkSmartPointer<vtkNIFTIImageReader>::New();
    niftireader->SetFileName(fileName.c_str());
    niftireader->Update();
    input = niftireader->GetOutput();
    vtkMatrix4x4* qMatrix = niftireader->GetQFormMatrix();
    qMatrix->Print(std::cout);
    int inputDims[3] = { 0 };
    int extent[6] = {0};
    double origin[3] = { 0 };
    double spacing[3] = { 0 };
    vtkNew<vtkMatrix3x3> mat;
    input->GetDimensions(inputDims);
    input->GetExtent(extent);
    input->GetOrigin(origin);
    input->GetSpacing(spacing);
  vtkSmartPointer<vtkImageReslice> pReslice = vtkSmartPointer<vtkImageReslice>::New();
  //pReslice->SetOutputOrigin(origin);
  double center[3];
  center[0] = origin[0] /*+ spacing[0] * 0.5 * (extent[0] + extent[1])*/;
  center[1] = origin[1] + spacing[1] * 0.5 * (extent[2] + extent[3]);
  center[2] = origin[2] /*+ spacing[2] * 0.5 * (extent[4] + extent[5])*/;

  static double axialElements[16] = {
      0, 1, 0, 0,
      0, 0, 1, 0,
      1, 0, 0, 0,
      0, 0, 0, 1
  };

  vtkSmartPointer<vtkMatrix4x4> resliceAxes =
      vtkSmartPointer<vtkMatrix4x4>::New();
  resliceAxes->DeepCopy(axialElements);
  resliceAxes->SetElement(0, 3, center[0]);
  resliceAxes->SetElement(1, 3, center[1]);
  resliceAxes->SetElement(2, 3, center[2]);
  //pReslice->SetOutputExtent(ext);
  pReslice->SetOutputDimensionality(2);
  pReslice->SetResliceAxes(resliceAxes);
  pReslice->SetAutoCropOutput(1);//！！！一定要加这句话
  pReslice->SetInputData(input);
  pReslice->Update();

  vtkImageData* extracted = pReslice->GetOutput();
  //extracted->SetOrigin(origin);
  int* extractedDims = extracted->GetDimensions();
  std::cout << "Dims: "
            << " x: " << extractedDims[0] << " y: " << extractedDims[1]
            << " z: " << extractedDims[2] << std::endl;
  std::cout << "Number of points: " << extracted->GetNumberOfPoints()
            << std::endl;
  std::cout << "Number of cells: " << extracted->GetNumberOfCells()
            << std::endl;
  string dstfileName = "resliced.nii.gz";
  vtkSmartPointer<vtkNIFTIImageWriter> envImageWriter = vtkSmartPointer<vtkNIFTIImageWriter>::New();
  envImageWriter->SetInputData(extracted);
  //envImageWriter->SetQFormMatrix(qMatrix);
  envImageWriter->SetFileName(dstfileName.c_str());
  envImageWriter->Write();

  return EXIT_SUCCESS;
}

提取中心层片 y轴切片

提取中心层片，z轴切片

 double center[3];
  center[0] = origin[0] /*+ spacing[0] * 0.5 * (extent[0] + extent[1])*/;
  center[1] = origin[1] /*+ spacing[1] * 0.5 * (extent[2] + extent[3])*/;
  center[2] = origin[2] + spacing[2] * 0.5 * (extent[4] + extent[5]);

  static double axialElements[16] = {
      1, 0, 0, 0,
      0, 1, 0, 0,
      0, 0, 1, 0,
      0, 0, 0, 1
  };

提取中心层片，x轴切片

 double center[3];
  center[0] = origin[0] + spacing[0] * 0.5 * (extent[0] + extent[1]);
  center[1] = origin[1] /*+ spacing[1] * 0.5 * (extent[2] + extent[3])*/;
  center[2] = origin[2] /*+ spacing[2] * 0.5 * (extent[4] + extent[5])*/;

  static double axialElements[16] = {
      0, 0, 1, 0,
      1, 0, 0, 0,
      0, 1, 0, 0,
      0, 0, 0, 1
  };

1.2 vtkExtractVOI提取单层图像

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

int main(int, char*[])
{
    string fileName = "D:/Dataset/Hip_Femur_Detection/Detect/BJ_02006.nii.gz";
    vtkSmartPointer<vtkImageData> input;
    vtkSmartPointer <vtkNIFTIImageReader> niftireader = vtkSmartPointer<vtkNIFTIImageReader>::New();
    niftireader->SetFileName(fileName.c_str());
    niftireader->Update();
    input = niftireader->GetOutput();
    vtkMatrix4x4* qMatrix = niftireader->GetQFormMatrix();
    qMatrix->Print(std::cout);
    int inputDims[3] = { 0 };
    int extent[6] = {0};
    double origin[3] = { 0 };
    double spacing[3] = { 0 };
    vtkNew<vtkMatrix3x3> mat;
    input->GetDimensions(inputDims);
    input->GetExtent(extent);
    input->GetOrigin(origin);
    input->GetSpacing(spacing);
  vtkNew<vtkExtractVOI> extractVOI;
  extractVOI->SetInputData(input);
  extractVOI->SetVOI(0, inputDims[0]-1,
                     0, inputDims[1]-1, inputDims[2] / 2, inputDims[2] / 2);
  extractVOI->Update();

  vtkImageData* extracted = extractVOI->GetOutput();
  //extracted->SetOrigin(origin);
  int* extractedDims = extracted->GetDimensions();
  std::cout << "Dims: "
            << " x: " << extractedDims[0] << " y: " << extractedDims[1]
            << " z: " << extractedDims[2] << std::endl;
  std::cout << "Number of points: " << extracted->GetNumberOfPoints()
            << std::endl;
  std::cout << "Number of cells: " << extracted->GetNumberOfCells()
            << std::endl;
  string dstfileName = "extractVOI.nii.gz";
  vtkSmartPointer<vtkNIFTIImageWriter> envImageWriter = vtkSmartPointer<vtkNIFTIImageWriter>::New();
  envImageWriter->SetInputData(extracted);
  envImageWriter->SetQFormMatrix(qMatrix);
  envImageWriter->SetFileName(dstfileName.c_str());
  envImageWriter->Write();

  return EXIT_SUCCESS;
}

提取中心层片，z轴切片

提取中心层片，x轴切片

 extractVOI->SetVOI(inputDims[0] / 2, inputDims[0]/2,
                     0, inputDims[1]-1, 0, inputDims[2]-1);

提取中心层片，y轴切片