VTK：读入DICOM，体绘制

#参照VTK自带的例程 Examples/GUI/Python/VolumeRenderWithBoxWidget.py
#从 http://www.vtk.org/doc/nightly/html/ 或者 手册中参考 vtkDICOMImageReader，vtkImageShiftScale等类的使用方法，修改例程文件如下：
#由于 volumeMapper 之能接受无符号数 unsigned short 或者 unsigned char，所以必须加以转换。这里使用vtkImageShiftScale

#!/usr/bin/env python

# Demonstrate how to use the vtkBoxWidget to control volume rendering
# within the interior of the widget.

import vtk
from vtk.util.misc import vtkGetDataRoot
VTK_DATA_ROOT = vtkGetDataRoot()

dicomReader = vtk.vtkDICOMImageReader()
dicomReader.SetDirectoryName('.../DICOM/PATH...')
dicomReader.Update()
dataSpacing = dicomReader.GetDataSpacing()
#由于volumeMapper之能接收无符号数，所以必须加以转换
srange = dicomReader.GetOutput().GetScalarRange()
min = srange[0]
max = srange[1]

diff = max-min
slope = 40000/diff
inter = -slope*min
shift = inter/slope

shifter = vtk.vtkImageShiftScale()
shifter.SetShift(shift)
shifter.SetScale(slope)
shifter.SetOutputScalarTypeToUnsignedShort()
shifter.SetInputConnection(dicomReader.GetOutputPort())
shifter.ReleaseDataFlagOff()
shifter.Update()
print min,max,slope,inter,shift

# Load a volume, use the widget to control what's volume
# rendered. Basically the idea is that the vtkBoxWidget provides a box
# which clips the volume rendering.

tfun = vtk.vtkPiecewiseFunction()
tfun.AddPoint(70.0, 0.0)
tfun.AddPoint(599.0, 0)
tfun.AddPoint(600.0, 0)
tfun.AddPoint(1195.0, 0)
tfun.AddPoint(1200, .2)
tfun.AddPoint(1300, .3)
tfun.AddPoint(2000, .3)
tfun.AddPoint(4095.0, 1.0)

ctfun = vtk.vtkColorTransferFunction()
ctfun.AddRGBPoint(0.0, 0.5, 0.0, 0.0)
ctfun.AddRGBPoint(600.0, 1.0, 0.5, 0.5)
ctfun.AddRGBPoint(1280.0, 0.9, 0.2, 0.3)
ctfun.AddRGBPoint(1960.0, 0.81, 0.27, 0.1)
ctfun.AddRGBPoint(4095.0, 0.5, 0.5, 0.5)
#
compositeFunction = vtk.vtkVolumeRayCastCompositeFunction()
volumeMapper = vtk.vtkVolumeRayCastMapper()
volumeMapper.SetInputConnection(shifter.GetOutputPort())
volumeMapper.SetVolumeRayCastFunction(compositeFunction)

volumeProperty = vtk.vtkVolumeProperty()
volumeProperty.SetColor(ctfun)
volumeProperty.SetScalarOpacity(tfun)
volumeProperty.SetInterpolationTypeToLinear()
volumeProperty.ShadeOn()

newvol = vtk.vtkVolume()
newvol.SetMapper(volumeMapper)
newvol.SetProperty(volumeProperty)

outline = vtk.vtkOutlineFilter()
outline.SetInputConnection(shifter.GetOutputPort())
outlineMapper = vtk.vtkPolyDataMapper()
outlineMapper.SetInputConnection(outline.GetOutputPort())
outlineActor = vtk.vtkActor()
outlineActor.SetMapper(outlineMapper)

# Create the RenderWindow, Renderer and both Actors
ren = vtk.vtkRenderer()
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)
iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)

# The SetInteractor method is how 3D widgets are associated with the
# render window interactor. Internally, SetInteractor sets up a bunch
# of callbacks using the Command/Observer mechanism (AddObserver()).
boxWidget = vtk.vtkBoxWidget()
boxWidget.SetInteractor(iren)
boxWidget.SetPlaceFactor(1.0)

# Add the actors to the renderer, set the background and size
ren.AddActor(outlineActor)
ren.AddVolume(newvol)

ren.SetBackground(0, 0, 0)
renWin.SetSize(300, 300)

# When interaction starts, the requested frame rate is increased.
def StartInteraction(obj, event):
    global renWin
    renWin.SetDesiredUpdateRate(10)

# When interaction ends, the requested frame rate is decreased to
# normal levels. This causes a full resolution render to occur.
def EndInteraction(obj, event):
    global renWin
    renWin.SetDesiredUpdateRate(0.001)

# The implicit function vtkPlanes is used in conjunction with the
# volume ray cast mapper to limit which portion of the volume is
# volume rendered.
planes = vtk.vtkPlanes()
def ClipVolumeRender(obj, event):
    global planes, volumeMapper
    obj.GetPlanes(planes)
    volumeMapper.SetClippingPlanes(planes)
 

# Place the interactor initially. The output of the reader is used to
# place the box widget.
boxWidget.SetInput(shifter.GetOutput())
boxWidget.PlaceWidget()
boxWidget.InsideOutOn()
boxWidget.AddObserver("StartInteractionEvent", StartInteraction)
boxWidget.AddObserver("InteractionEvent", ClipVolumeRender)
boxWidget.AddObserver("EndInteractionEvent", EndInteraction)

outlineProperty = boxWidget.GetOutlineProperty()
outlineProperty.SetRepresentationToWireframe()
outlineProperty.SetAmbient(1.0)
outlineProperty.SetAmbientColor(1, 1, 1)
outlineProperty.SetLineWidth(3)

selectedOutlineProperty = boxWidget.GetSelectedOutlineProperty()
selectedOutlineProperty.SetRepresentationToWireframe()
selectedOutlineProperty.SetAmbient(1.0)
selectedOutlineProperty.SetAmbientColor(1, 0, 0)
selectedOutlineProperty.SetLineWidth(3)

iren.Initialize()
renWin.Render()
iren.Start()