[vtkusers] z- buffer to distances from camera

[Umer Rafi]

Hi Everyone,

  I am new to VTK and rendering. I have a rendered depth map from VTK (file attached). What I want is to get the distance of each pixel in this depth map from camera. Can any body tell me how to convert z-buffer values to actual distances from camera. I will really appreciate any help and a sample code snippet to get me started. 
Thanks in  advance.

Regards
Umer
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