[vtk-developers] How to assign a specific color to a region during surface reconstruction using vtkDiscreteMarchingCubes

[lf]

Hello, everyone,

I got a problem when I do surface reconstruction using vtkDiscreteMarchingCubes. Can somebody give me a help?
Thank you very much.
Fei Liu

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Objective:
we want to do surface reconstruction for some segmented CT images.
For each segmented image, we have got four differentiated regions: kidney (gray value 220), tumor (gray value 230), vessels (gray value 240), and spine (gray value 250). The left area has a gray value of 0.

When we do surface reconstruction for these segmented CT images, we want to get the following result:
each of the four regions (kidney, tumor, vesels and spine) is displayed with a different color given by lookuptake.
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Current problem:
However, it does not work using the following codes, that is, the selected colors in the lookuptable are not assigned to the four regions.


Here are the codes:

{
    vtkSmartPointer<vtkImageAppend > append = vtkSmartPointer<vtkImageAppend >::New();
//then I put images in append

//using vtkDiscreteMarchingCubes for reconstruction
    vtkSmartPointer<vtkDiscreteMarchingCubes> dmc = vtkSmartPointer<vtkDiscreteMarchingCubes>::New();
    dmc->SetInputConnection(append->GetOutputPort());        
    dmc->SetValue(0, 220);
    dmc->SetValue(1, 230);
    dmc->SetValue(2, 240);
    dmc->SetValue(3, 250);
    dmc->Update();

//optimization
    vtkSmartPointer<vtkDecimatePro> deci = vtkSmartPointer<vtkDecimatePro>::New(); //减少数据读取点，以牺牲数据量加速交互
    deci->SetTargetReduction(0.3);
    deci->SetInputConnection(dmc->GetOutputPort());
    vtkSmartPointer<vtkSmoothPolyDataFilter> smooth = vtkSmartPointer<vtkSmoothPolyDataFilter>::New();  //使图像更加光滑
    smooth->SetInputConnection(deci->GetOutputPort());
    smooth->SetNumberOfIterations(200);
    vtkSmartPointer<vtkPolyDataNormals> skinNormals = vtkSmartPointer<vtkPolyDataNormals>::New();  //求法线
    skinNormals->SetInputConnection(smooth->GetOutputPort());
    skinNormals->SetFeatureAngle(60.0);
    vtkSmartPointer<vtkStripper> stripper = vtkSmartPointer<vtkStripper>::New();   //将三角形连接起来
    stripper->SetInputConnection(skinNormals->GetOutputPort());

// Map the scalar values in the image to colors with a lookup table:
    vtkSmartPointer<vtkLookupTable> lookupTable = vtkSmartPointer<vtkLookupTable>::New();
    lookupTable->SetNumberOfTableValues(4);    
    lookupTable->SetTableValue(0, 0.8900, 0.8100, 0.3400, 1); // Banana
    lookupTable->SetTableValue(1, 1.0000, 0.3882, 0.2784, 1); // Tomato    
    lookupTable->SetTableValue(2, 0.7400, 0.9900, 0.7900, 1); // Mint
    lookupTable->SetTableValue(3, 0.2000, 0.6300, 0.7900, 1); // Peacock
    lookupTable->Build();

//define a new actor and vtkPolyDataMapper mapper
    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputConnection(stripper->GetOutputPort());
    mapper->ScalarVisibilityOn();
    mapper->SetScalarRange(220, 250);
    mapper->SetScalarModeToUseCellData();
    mapper->SetLookupTable(lookupTable);
    vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);

//add actor to a render and display the result
    m_StaticSurface1.GetvtkRenderer()->AddActor(actor);
    m_StaticSurface1.GetvtkRenderer()->ResetCamera();
}





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