Abstract: An aerial survey method to determine ground contours establishes a reference plane to which all contour measurements are referred. The reference plane intersects a rotating beam optical radar unit which includes a receiving antenna. The antenna receives signal waves emanating from the aircraft to measure the relative height of the aircraft with respect to the reference plane. A survey track along the ground for the aircraft is determined and the position of the aircraft along the track is continuously measured. The aircraft is flown continuously along the track and repeated altitude measurements of the aircraft are made. The relative height of the aircraft with respect to the reference plane, the altitude of the aircraft above the ground and the position of the aircraft along the survey track are correlated to determine the ground contours.

Abstract: A laser beam level control system for an earth-moving machine is provided with an automatic override function to temporarily block blade-down signals and raise the blade when lowering it or leaving it at its previous height would increase the force required to drive the machine across the ground above a preselected value which does not exceed the tractional force capability of the machine's drive wheels or exceed the machine's available horsepower.

Abstract: An aerial surveying method to determine ground contour utilizes a rotating laser beam to establish a horizontal reference plane to which all contour measurements are referred. A stacked-array optical sensor, suspended below the aircraft, is utilized to measure the relative height of the aircraft with respect to the reference plane. A survey track along the ground for the aircraft is determined and the position of the aircraft along the track is continuously measured. The aircraft is flown continuously along the track and repeated altitude measurements of the aircraft are continuously made. The relative height of the aircraft with respect to the laser beam, the altitude of the aircraft above the ground and the position of the aircraft along the survey track are correlated to determine the ground contours.

Abstract: A laser beam level control system for an earth-moving machine is provided with an automatic override function to temporarily block blade-down signals and raise the blade when lowering it or leaving it at its previous height would increase the force required to drive the machine across the ground above a preselected value which does not exceed the tractional force capability of the machine's drive wheels or exceed the machine's available horsepower.