Exactly ! But imagine the shade of a style passing on the top of that awesome stick , parallel to the poles' axis. (That style is going toward North direction and angle with the horizontal plane is latitude).
The very important point of that stick is the top.
At equinox -spring or fall- the movement of the shade on a plane -ie wall or ground- of any fixed point - ie the end of a branch - is a straight line who gives you your orientation aso of the wall.
Ideally you should use the poles' axis but, seen from the sun producting the shade, the angular distance to your style is neglectable.