Sensor to detect x and y co-ordinate changes when worn

Hi,

I am a new member. Is there a wearable sensor that can detect x and y co-ordinate changes? i.e height from ground and also horizontal displacement relative to original position?

A GPS unit comes to mind, but they don’t work indoors.

My question at viewtopic.php?f=94&t=57109 might be related. The page at https://en.wikipedia.org/wiki/Positioning_system might also be.

Should this be moved to viewforum.php?f=68?