Main frames in package
mapcoordinates relative to the point of flight controller initialization: the white grid in the illustration;
base_link— coordinates relative to the quadcopter: schematic image of the quadcopter in the illustration;
body— coordinates relative to the quadcopter regardless of pitch and roll: red, blue and green lines in the illustration.
In accordance with the agreement, for frames associated with the copter, the X-axis directed forward, Y – to the left, and Z – up.
More clearly, 3D visualization of the coordinate systems can be viewed using rviz.