coordinate system

HI all,I need your help.

I have a basic problem, but it's confused.
In the world coordinate system,X axis、Y axis、Z axis,How do they define it?
Look at the picture below. How do these axes correspond?

Thank you for your help!


Cesium uses the ECEF coordinate system (

If you’re trying to place geometry or objects on the surface, I would use latitude/longitude/height since that’s easier to position. You can convert from cartographic to cartesian and vice versa with the Cartographic class: