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()