Hello everyone,
I’m trying to get familiar with vtk in python.
I’d like to do ray tracing using vtk 8.
So I found the following example at https://vtk.org/Wiki/VTK/Examples/Python/vtkWithNumpy
(reproducing it to freeze it in time)
# An example from scipy cookbook demonstrating the use of numpy arrys in vtk
import vtk
from numpy import *
# We begin by creating the data we want to render.
# For this tutorial, we create a 3D-image containing three overlaping cubes.
# This data can of course easily be replaced by data from a medical CT-scan or anything else three dimensional.
# The only limit is that the data must be reduced to unsigned 8 bit or 16 bit integers.
data_matrix = zeros([75, 75, 75], dtype=uint8)
data_matrix[0:35, 0:35, 0:35] = 50
data_matrix[25:55, 25:55, 25:55] = 100
data_matrix[45:74, 45:74, 45:74] = 150
# For VTK to be able to use the data, it must be stored as a VTK-image. This can be done by the vtkImageImport-class which
# imports raw data and stores it.
dataImporter = vtk.vtkImageImport()
# The preaviusly created array is converted to a string of chars and imported.
data_string = data_matrix.tostring()
dataImporter.CopyImportVoidPointer(data_string, len(data_string))
# The type of the newly imported data is set to unsigned char (uint8)
dataImporter.SetDataScalarTypeToUnsignedChar()
# Because the data that is imported only contains an intensity value (it isnt RGB-coded or someting similar), the importer
# must be told this is the case.
dataImporter.SetNumberOfScalarComponents(1)
# The following two functions describe how the data is stored and the dimensions of the array it is stored in. For this
# simple case, all axes are of length 75 and begins with the first element. For other data, this is probably not the case.
# I have to admit however, that I honestly dont know the difference between SetDataExtent() and SetWholeExtent() although
# VTK complains if not both are used.
dataImporter.SetDataExtent(0, 74, 0, 74, 0, 74)
dataImporter.SetWholeExtent(0, 74, 0, 74, 0, 74)
# The following class is used to store transparencyv-values for later retrival. In our case, we want the value 0 to be
# completly opaque whereas the three different cubes are given different transperancy-values to show how it works.
alphaChannelFunc = vtk.vtkPiecewiseFunction()
alphaChannelFunc.AddPoint(0, 0.0)
alphaChannelFunc.AddPoint(50, 0.05)
alphaChannelFunc.AddPoint(100, 0.1)
alphaChannelFunc.AddPoint(150, 0.2)
# This class stores color data and can create color tables from a few color points. For this demo, we want the three cubes
# to be of the colors red green and blue.
colorFunc = vtk.vtkColorTransferFunction()
colorFunc.AddRGBPoint(50, 1.0, 0.0, 0.0)
colorFunc.AddRGBPoint(100, 0.0, 1.0, 0.0)
colorFunc.AddRGBPoint(150, 0.0, 0.0, 1.0)
# The preavius two classes stored properties. Because we want to apply these properties to the volume we want to render,
# we have to store them in a class that stores volume prpoperties.
volumeProperty = vtk.vtkVolumeProperty()
volumeProperty.SetColor(colorFunc)
volumeProperty.SetScalarOpacity(alphaChannelFunc)
# This class describes how the volume is rendered (through ray tracing).
compositeFunction = vtk.vtkVolumeRayCastCompositeFunction()
# We can finally create our volume. We also have to specify the data for it, as well as how the data will be rendered.
volumeMapper = vtk.vtkVolumeRayCastMapper()
volumeMapper.SetVolumeRayCastFunction(compositeFunction)
volumeMapper.SetInputConnection(dataImporter.GetOutputPort())
# The class vtkVolume is used to pair the preaviusly declared volume as well as the properties to be used when rendering that volume.
volume = vtk.vtkVolume()
volume.SetMapper(volumeMapper)
volume.SetProperty(volumeProperty)
# With almost everything else ready, its time to initialize the renderer and window, as well as creating a method for exiting the application
renderer = vtk.vtkRenderer()
renderWin = vtk.vtkRenderWindow()
renderWin.AddRenderer(renderer)
renderInteractor = vtk.vtkRenderWindowInteractor()
renderInteractor.SetRenderWindow(renderWin)
# We add the volume to the renderer ...
renderer.AddVolume(volume)
# ... set background color to white ...
renderer.SetBackground(0,0,0)
# ... and set window size.
renderWin.SetSize(400, 400)
# A simple function to be called when the user decides to quit the application.
def exitCheck(obj, event):
if obj.GetEventPending() != 0:
obj.SetAbortRender(1)
# Tell the application to use the function as an exit check.
renderWin.AddObserver("AbortCheckEvent", exitCheck)
renderInteractor.Initialize()
# Because nothing will be rendered without any input, we order the first render manually before control is handed over to the main-loop.
renderWin.Render()
renderInteractor.Start()
I have the following here surely related to API changes 
module 'vtk' has no attribute 'vtkVolumeRayCastCompositeFunction'
module 'vtk' has no attribute 'vtkVolumeRayCastMapper'
Maybe this line is problematic too, but cannot affirm because I could not find the relevant new way to do this.
volumeMapper.SetVolumeRayCastFunction(compositeFunction)
Here is the result of
pip freeze
apptools==4.4.0
attrs==19.1.0
backcall==0.1.0
bleach==3.1.0
configobj==5.0.6
cycler==0.10.0
decorator==4.4.0
defusedxml==0.6.0
entrypoints==0.3
envisage==4.7.2
fenics==2019.1.0
fenics-dijitso==2019.1.0
fenics-ffc==2019.1.0.post0
fenics-fiat==2019.1.0
fenics-ufl==2019.1.0
ipykernel==5.1.1
ipython==7.5.0
ipython-genutils==0.2.0
ipywidgets==7.4.2
jedi==0.13.3
Jinja2==2.10.1
jsonschema==3.0.1
jupyter==1.0.0
jupyter-client==5.2.4
jupyter-console==6.0.0
jupyter-core==4.4.0
jupyterlab==0.35.6
jupyterlab-server==0.2.0
kiwisolver==1.1.0
MarkupSafe==1.1.1
matplotlib==3.1.0
mayavi==4.6.2
mistune==0.8.4
mpmath==1.1.0
nbconvert==5.5.0
nbformat==4.4.0
notebook==5.7.8
numpy==1.16.4
pandocfilters==1.4.2
parso==0.4.0
pexpect==4.7.0
pickleshare==0.7.5
prometheus-client==0.7.0
prompt-toolkit==2.0.9
ptyprocess==0.6.0
pyface==6.1.0
Pygments==2.4.2
pyparsing==2.4.0
PyQt5==5.12.2
PyQt5-sip==4.19.17
pyrsistent==0.15.2
python-dateutil==2.8.0
pyzmq==18.0.1
qtconsole==4.5.1
Send2Trash==1.5.0
six==1.12.0
sympy==1.4
terminado==0.8.2
testpath==0.4.2
tornado==6.0.2
traitlets==4.3.2
traits==5.1.1
traitsui==6.1.1
vtk==8.1.2
wcwidth==0.1.7
webencodings==0.5.1
widgetsnbextension==3.4.2
I would be really grateful if someone could help me figure out what is the new way of doing this. I really need the ray tracer quality !
Thank you very much,
Joachim