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 <vtkExtractVOI.h>
#include <vtkImageCast.h>
#include <vtkImageData.h>
#include <vtkNew.h>
#include <vtkNIFTIImageReader.h>
#include <vtkNIFTIImageWriter.h>
#include <vtkImageReslice.h>
#include <string>
#include <vtkMatrix4x4.h>
#include <vtkSmartPointer.h>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 <vtkExtractVOI.h>
#include <vtkImageActor.h>
#include <vtkImageCast.h>
#include <vtkImageData.h>
#include <vtkImageMandelbrotSource.h>
#include <vtkImageMapper3D.h>
#include <vtkInteractorStyleImage.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkNew.h>
#include <vtkNIFTIImageReader.h>
#include <vtkNIFTIImageWriter.h>
#include <vtkMatrix3x3.h>
#include <string>
#include <vtkMatrix4x4.h>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