ABSTRACT
If the relative position of two points is described by the 3D orientation of a line joining them, then, in general, tilt is the angular amount that the orientation has changed, in a vertical plane, from a previous direction or from a reference direction. If the original or reference orientation is nearly horizontal, then the term “tilt” is usually used. If it is nearly vertical, then the change is oen regarded as “inclination.” Here, “tilt” will refer to either. e two points can be separated by a discernable amount, the base, or the tilt can be measured at a point with the reference orientation being dened by the direction of the force of gravity at that point. us, the same instrument that measures tilt at a point can be called either a tiltmeter or an inclinometer (or clinometer), depending on the interpretation of the results. e instrument used to measure a series of tilts along any vertical orientation is oen called an inclinometer (e.g., [1]).
