如题，我有一组胸腔的ct图，我需要单独分割出血管的模型，但用vtkMarchingCube好像把包括血管的其他组织都显示出来了，萌新只会用MC里面的setvalue,求教如何将下面盆骨的大动脉分割出来？

这是我的部分代码，最后要输出obj文件，大佬求带
vtkSmartPointer<vtkMarchingCubes>marchingcube = vtkSmartPointer<vtkMarchingCubes>::New();
marchingcube->SetInputConnection(Reader->GetOutputPort());
marchingcube->SetValue(0, ctValue);
vtkSmartPointer<vtkDecimatePro> deci = vtkSmartPointer<vtkDecimatePro>::New();
deci->SetInputConnection(marchingcube->GetOutputPort());
deci->SetTargetReduction(reduct);
vtkSmartPointer<vtkSmoothPolyDataFilter> smooth = vtkSmartPointer<vtkSmoothPolyDataFilter>::New();
smooth->SetInputConnection(deci->GetOutputPort());
smooth->SetNumberOfIterations(100);
vtkSmartPointer<vtkPolyDataNormals> skinNormals = vtkSmartPointer<vtkPolyDataNormals>::New();
skinNormals->SetInputConnection(smooth->GetOutputPort());
vtkSmartPointer<vtkStripper>skinStripper = vtkSmartPointer<vtkStripper>::New();
skinStripper->SetInputConnection(skinNormals->GetOutputPort());
vtkSmartPointer<vtkPolyDataMapper> skinMapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
skinMapper->SetInputConnection(skinStripper->GetOutputPort());
skinMapper->ScalarVisibilityOff();
vtkSmartPointer<vtkActor> skin =
vtkSmartPointer<vtkActor>::New();
skin->SetMapper(skinMapper);
vtkSmartPointer<vtkRenderer> aRenderer = vtkSmartPointer<vtkRenderer>::New();
aRenderer->AddActor(skin);
vtkSmartPointer<vtkRenderWindow> renWin = vtkSmartPointer<vtkRenderWindow>::New();
renWin->AddRenderer(aRenderer);
vtkSmartPointer<vtkRenderWindowInteractor> iren =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
iren->SetRenderWindow(renWin);
vtkSmartPointer<vtkOBJExporter> porter = vtkSmartPointer<vtkOBJExporter>::New();
porter->SetFilePrefix(outputFile.c_str());
porter->SetInput(renWin);
porter->Write();

分割血管不是这个套路，去看看VMTK吧，孩纸