如何选择 vtkVolumeMapper 使用的标量

Question

我有一个包含多个数据数组的体积，我使用 vtkVolumeMapper (vtkFixedPointVolumeRayCastMapper) 渲染它。

如何告诉映射器使用特定数组作为标量？（SelectColorArray 不是 vtkVolumeMapper 的函数）

我正在使用 VTK 6

    # Create the reader for the data
    reader = vtk.vtkXMLImageDataReader()
    reader.SetFileName(self.scan_analysis.content.vtk_path)
    reader.GetOutput().GetPointData().SetActiveScalars('smooth')

    # Create transfer mapping scalar value to opacity
    opacityTransferFunction = vtk.vtkPiecewiseFunction()
    opacityTransferFunction.AddPoint(5, 0.0)
    opacityTransferFunction.AddPoint(80, 0.4)
    opacityTransferFunction.AddPoint(81, 0.0)
    opacityTransferFunction.AddPoint(100, 0.0)

    # Create transfer mapping scalar value to color
    lut = vtk.vtkColorTransferFunction()
    lut.AddRGBPoint(0.0, 0.0, 0.0, 1.0)
    lut.AddRGBPoint(50.0, 1.0, 1.0, 1.0)
    lut.AddRGBPoint(100.0, 1.0, 0.0, 0.0)

    # The property describes how the data will look
    volumeProperty = vtk.vtkVolumeProperty()
    volumeProperty.SetColor(lut)
    volumeProperty.SetScalarOpacity(opacityTransferFunction)
    volumeProperty.ShadeOn()
    volumeProperty.SetInterpolationTypeToLinear()

    # The mapper / ray cast function know how to render the data
    #volumeMapper = vtk.vtkGPUVolumeRayCastMapper()
    #volumeMapper = vtk.vtkSmartVolumeMapper()
    volumeMapper = vtk.vtkFixedPointVolumeRayCastMapper()
    volumeMapper.SetBlendModeToComposite()
    volumeMapper.SetInputConnection(reader.GetOutputPort())
    volumeMapper.SelectColorArray('smooth') ## -> exception

    # The volume holds the mapper and the property and
    # can be used to position/orient the volume
    volume = vtk.vtkVolume()
    volume.SetMapper(volumeMapper)
    volume.SetProperty(volumeProperty)

此外，是否可以将元胞标量用于体积映射器？

谢谢

更新：我结束了对每个标量使用不同的 vtk 文件。它可以工作并且不会消耗更多磁盘 space... 但我知道这不是正确的解决方案（令人沮丧）

Answer 1

我找到了以下解决方案，使用 SetScalarsName:

from vtk import (vtkUnstructuredGridReader, vtkDataSetMapper, vtkActor,
                 vtkRenderer, vtkRenderWindow, vtkRenderWindowInteractor)

# Read the source file.
reader = vtkUnstructuredGridReader()
reader.SetFileName("FileName")

reader.SetScalarsName("ScalarNameYouWant")  ### this command should do it

#reader.ReadAllScalarsOn()
reader.Update()  # Needed because of GetScalarRange
output = reader.GetOutput()
output_port = reader.GetOutputPort()
scalar_range = output.GetScalarRange()
# Create the mapper that corresponds the objects of the vtk file
# into graphics elements
mapper = vtkDataSetMapper()
mapper.SetInputConnection(output_port)
mapper.SetScalarRange(scalar_range)
# Create the Actor
actor = vtkActor()
actor.SetMapper(mapper)

# Create the Renderer
renderer = vtkRenderer()
renderer.AddActor(actor)
renderer.SetBackground(1, 1, 1) # Set background to white

# Create the RendererWindow
renderer_window = vtkRenderWindow()
renderer_window.AddRenderer(renderer)

# Create the RendererWindowInteractor and display the vtk_file
interactor = vtkRenderWindowInteractor()
interactor.SetRenderWindow(renderer_window)
interactor.Initialize()
interactor.Start()

在此处找到解决方案：
https://vtk.org/gitweb?p=VTK.git;a=blob;f=Examples/DataManipulation/Python/pointToCellData.py

如何选择 vtkVolumeMapper 使用的标量

How to choose the scalar used by vtkVolumeMapper

python

vtk