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	VTK Basics
3.5.2. vtkContourFilter vs. vtkMarchingCubes The best way to compare these two is to look at the same region of interest and see how they match up. Below is the code to make the datasets render.
import Tkinter import vtk from vtk.tk.vtkTkRenderWindowInteractor import vtkTkRenderWindowInteractor # Prepare to read the file readerVolume = vtk.vtkImageReader() readerVolume.SetDataScalarType( vtk.VTK_UNSIGNED_SHORT ) readerVolume.SetFileDimensionality( 3 ) readerVolume.SetDataExtent ( 0,255, 0,255, 0,576) readerVolume.SetDataSpacing( 1,1,1 ) readerVolume.SetNumberOfScalarComponents( 1 ) readerVolume.SetDataByteOrderToBigEndian() readerVolume.SetFileName( "./Female.raw" ) # Extract the region of interest voiHead = vtk.vtkExtractVOI() voiHead.SetInput( readerVolume.GetOutput() ) voiHead.SetVOI( 0,255, 60,255, 0,100 ) voiHead.SetSampleRate( 1,1,1 ) # Generate an isosurface # UNCOMMENT THE FOLLOWING LINE FOR CONTOUR FILTER # contourBoneHead = vtk.vtkContourFilter() contourBoneHead = vtk.vtkMarchingCubes() contourBoneHead.SetInput( voiHead.GetOutput() ) contourBoneHead.ComputeNormalsOn() contourBoneHead.SetValue( 0, 1250 ) # Bone isovalue # Take the isosurface data and create geometry geoBoneMapper = vtk.vtkPolyDataMapper() geoBoneMapper.SetInput( contourBoneHead.GetOutput() ) geoBoneMapper.ScalarVisibilityOff() # Take the isosurface data and create geometry actorBone = vtk.vtkLODActor() actorBone.SetNumberOfCloudPoints( 1000000 ) actorBone.SetMapper( geoBoneMapper ) actorBone.GetProperty().SetColor( 1, 1, 1 ) # Create renderer ren = vtk.vtkRenderer() ren.SetBackground( 0.329412, 0.34902, 0.427451 ) #Paraview blue ren.AddActor(actorBone) # Create a window for the renderer of size 250x250 renWin = vtk.vtkRenderWindow() renWin.AddRenderer(ren) renWin.SetSize(250, 250) # Set an user interface interactor for the render window iren = vtk.vtkRenderWindowInteractor() iren.SetRenderWindow(renWin) # Start the initialization and rendering iren.Initialize() renWin.Render() iren.Start() Example 3.2: Code to generate compare the vtkMarchingCubes and vtkContourFilter
Below is a side-by-side comparison of the two.
(a)			(b)
Figure 3.2: Renderings of the head section of the Visible Woman dataset using a bone isosurface value. (a) vtkContourFilter, (b) vtkMarchingCubes
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