[vtkusers] Newbie: what's the vtkContourValues for?

[#CHEN CHENG#]

Hi,
I am now trying to modify the Medical example coming with VTK.
 
I cannot understand what is the vtkContourValues for. I use matlab to print out all the 64x64 data in the quater.x file,  no exact value of 500 or 1200 exist. 
 
It seems that the vtkContourFilter->SetValue(0, 500) just gives a rough guidance to te contour detection, but I cannot find any further details about vtkContourValues.
 
Can anyone help?
 
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Chen Cheng
 
S2.1-B4-01
Intelligent Robotics Lab
Nanyang Technological University
Singapore, 639798
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