why we need kinect calibration?

Now I'm working on kinect with matlab 2013a my aim is using it for mobile robot navigation, it work well and i get distance values from depth image, i want to ask about calibration why i need calibration for kinect sensor

[Liviu Ivanescu]

Hi, I'm starting to do a similar application with Kinect and EV3 robot from Lego Mindstorms. Do you have any experience or code to share? Thanks!

[Martin Schätz]

Hi, what kind of calibration do you have in mind? Calibration through the image on case for Kinect? Calibration of depth or color sensor? Or any other?