Direct leveling by traversing ₪ 1.1 Principle

 

Direct leveling consists of determining the height difference ΔHAB between two points A and B using a device : the level and a vertical scale called a staff 

The telescopen level consists of a sighting optic rotating around a vertical axis : it therefore defines a horizontal  sighting plane. The target is placed successively on the two point A and B . The operator reads the valus LA on the staff placed at A and the value LB on the staff placed at B.

This drio is an algebraic value whose sign indicates wherher B is higher or lower than A (if ΔHAB is negativee then B is lower than A).

The altitude of a point A notedAlta is the distance counted along the vertical which separates it from the geoind (leveel 0 surface. If the altitude of point A id knoxn,, we can deduce that of point B.