Kinect - face distance in cm


I’m looking for the formular to calculate the face distance to the camera/sensor. The Node Face (Kinect Microsoft) gives “PositionXYZ” … what would be the easies way to calculate the distance in cm from the “Z” value?

I’ve found this graph sites/default/files/imagecache/large/images/Bild%20123.png

… I assume this relates to the kinect depth map values comming from “Depth (Kinect Microsoft)” ?!

Makes it sense to get my XY ROI from the facetracker and then Pipet the Depthmap Texture to get my values of interest?! Or ist there a faster/easier way to archive what I want?


the PositionXYZ is in meters. so a value of 0.8 means 80cm.