填充三角面片的内部空间 vtkpolydata 转换为vtkimageData

vtkSmartPointer<vtkImageData> polyDataToImageData(vtkSmartPointer<vtkPolyData> polydata, vtkSmartPointer<vtkImageData> imageData)
{
    double origin[3];
    double spacing[3]; // desired volume spacing
    if (imageData)
    {
        imageData->GetOrigin(origin);
        imageData->GetSpacing(spacing);
    }else
    {
        imageData = vtkSmartPointer<vtkImageData>::New();
        double bounds[6];
        polydata->GetBounds(bounds);
        
        spacing[0] = 0.5;
        spacing[1] = 0.5;
        spacing[2] = 0.5;
        imageData->SetSpacing(spacing);

  &nbs