PolyDataContourToImageData 3D集合图像转换成等效3D二值图像

一：主要的知识点

1、说明

本文只是教程内容的一小段，因博客字数限制，故进行拆分。主教程链接：vtk教程------逐行解析官网所有Python示例-CSDN博客

2、知识点纪要

本段代码主要涉及的有①三维图形转换为3D体素数据

二：代码及注释

import math

import vtkmodules.vtkRenderingOpenGL2
import vtkmodules.vtkInteractionStyle
from vtkmodules.vtkFiltersSources import vtkSphereSource
from vtkmodules.vtkFiltersCore import vtkCutter, vtkStripper
from vtkmodules.vtkCommonDataModel import vtkImageData, vtkPlane
from vtkmodules.vtkIOXML import vtkXMLPolyDataWriter
from vtkmodules.vtkCommonCore import VTK_UNSIGNED_CHAR
from vtkmodules.vtkFiltersModeling import vtkLinearExtrusionFilter
from vtkmodules.vtkImagingStencil import vtkImageStencil, vtkPolyDataToImageStencil
from vtkmodules.vtkIOImage import vtkMetaImageWriter, vtkPNGWriter


def main():
    # 创建一个3D图形
    sphereSource = vtkSphereSource()
    sphereSource.SetPhiResolution(30)
    sphereSource.SetThetaResolution(30)
    sphereSource.SetCenter(40, 40, 40)
    sphereSource.SetRadius(20)

    # 切割数据集的"刀"
    # 首先先定义这个刀是什么，需要使用隐函数定义
    cutPlane = vtkPlane()
    cutPlane.SetOrigin(sphereSource.GetCenter())
    cutPlane.SetNormal(0, 0, 1)

    circleCutter = vtkCutter()
    circleCutter.SetInputConnection(sphereSource.GetOutputPort())
    circleCutter.SetCutFunction(cutPlane)

    stripper = vtkStripper()
    stripper.SetInputConnection(circleCutter.GetOutputPort())
    stripper.Update()

    circle = stripper.GetOutput()
    # 写入vtp文件
    polyDataWriter = vtkXMLPolyDataWriter()
    polyDataWriter.SetInputData(circle)
    polyDataWriter.SetFileName("circle.vtp")
    polyDataWriter.SetCompressorTypeToNone()  # 不适用任何压缩
    polyDataWriter.SetDataModeToAscii()  # 设置输出文件中的数据以ASCII（文本）格式存储
    polyDataWriter.Write()

    # 准备一个体素数据
    whiteImage = vtkImageData()
    bounds = [0] * 6
    circle.GetBounds(bounds)
    spacing = [0.5, 0.5, 0.5]
    whiteImage.SetSpacing(spacing)

    # 计算这个体素数据的维度
    dim = [0] * 3
    for i in range(3):
        dim[i] = int(math.ceil((bounds[i * 2 + 1] - bounds[i * 2]) / spacing[i])) + 1
        if dim[i] < 1:
            dim[i] = 1
    whiteImage.SetDimensions(dim)  # 算是设置了图像体素的数量
    # SetExtent 设置了图像的索引范围 确保了生成的 3D 图像的体素网格是最小且精确的，既不浪费内存，又能完整地覆盖输入的几何体
    whiteImage.SetExtent(0, dim[0] - 1, 0, dim[1] - 1, 0, dim[2] - 1)
    origin_shift = 5 * 0.5
    origin = [0] * 3
    origin[0] = bounds[0] - origin_shift
    origin[1] = bounds[2] - origin_shift
    origin[2] = bounds[4] - origin_shift
    # 上述添加origin_shift是为了vtkImageData能够完全包裹住mesh
    whiteImage.SetOrigin(origin)
    # AllocateScalars # 为图像的体素数据分配内存。VTK_UNSIGNED_CHAR（无符号字符，范围 0-255），1 表示每个体素有一个分量（即灰度值）
    whiteImage.AllocateScalars(VTK_UNSIGNED_CHAR, 1)

    # 将 整个 3D 图像（体素网格）预先填充为前景值（即白色）
    # inval = 255
    outval = 0
    # count = whiteImage.GetNumberOfPoints()
    # for i in range(count):
    #     whiteImage.GetPointData().GetScalars().SetTuple1(i, inval)

    # 上述for循环的简便替代方法
    whiteImage.GetPointData().GetScalars().Fill(255)

    extrude = vtkLinearExtrusionFilter()
    extrude.SetInputData(circle)
    extrude.SetScaleFactor(1.0)  # 设置挤压的比例因子
    extrude.SetExtrusionTypeToVectorExtrusion()  # 设置为向量挤压，而非几何体表面的法线定义
    extrude.SetVector(0, 0, 1)  # 设置挤压的向量
    extrude.Update()

    pol2stenc = vtkPolyDataToImageStencil()
    pol2stenc.SetInputConnection(extrude.GetOutputPort())
    pol2stenc.SetTolerance(0)  # 帮助过滤垂直面
    pol2stenc.SetOutputOrigin(origin)
    pol2stenc.SetOutputSpacing(spacing)
    pol2stenc.SetOutputWholeExtent(whiteImage.GetExtent())
    pol2stenc.Update()

    imgstenc = vtkImageStencil()
    """
    tkImageStencil 是另一个关键过滤器，它接收一个图像作为输入，并根据一个模板（Stencil）修改该图像的像素值。
    """
    imgstenc.SetInputData(whiteImage)
    imgstenc.SetStencilConnection(pol2stenc.GetOutputPort())
    imgstenc.ReverseStencilOff()
    imgstenc.SetBackgroundValue(outval)
    imgstenc.Update()

    imageWriter = vtkMetaImageWriter()
    imageWriter.SetFileName('labelImage.mhd')
    imageWriter.SetInputConnection(imgstenc.GetOutputPort())
    imageWriter.Write()

    imageWriter = vtkPNGWriter()
    imageWriter.SetFileName('labelImage.png')
    imageWriter.SetInputConnection(imgstenc.GetOutputPort())
    imageWriter.Write()

if __name__ == '__main__':
    main()