English

A NETWORK. In PHOTOGRAPHY, a glass plate on which is etched a NETWORK of fine lines. Sometimes used as a focal-plane plate to provide a means of calibrating film DISTORTI­ON.

The graphical or analytical determination of a POSITION as the intersection of at least three lines of known relative direction to corresponding points of known POSITION. In PHOTOGRAMMETRY, the determination of the position and/or attitude of a CAMERA, or the PHOTOGRAPH taken with that CAMERA, with respect to the exterior co­ordinate system.

A place where anything is collected and stored, generally in large quantity; especially a POND, LAKE or BASIN, either natural or artificial, for the storage, regulation and control of water.

The separation by an optical system of parts of an object or of two or more objects close together. The degree of ability to make such a separation, called RESOLVING POWER, is expressed as the minimum distance between two objects that can be separated. The degree of ability of a radar set to indicate separately the echoes of two targets in range and bearing.

A mathe­matical expression of DEFINI­TION in a RADAR or OPTICAL SYSTEM, usually stated as the maximum number of lines per millimetre that can be seen as separate lines in the IMAGE.

Re-enforcement or prolongation of any wave motion, such as SOUND, RADIO WAVES, etc., resulting when the NATURAL FREQUENCY of the body or system in VIBRATION is equal to that of an impressed VIBRATION. In TIDES, the water movement resulting from the natu­ral PERIOD of OSCILLATION of a body of water which approximates the PERIOD of one of the TIDE-PRODUCING FORCES.

A transmitter, fitted to a submersible or on the seabed, which can be triggered by a hardwired external control signal to transmit an interrogation signal which is received by a TRANSDUCER or HYDROPHO­NE.

A RADIO RECEIVER which receives a reply from a TRANSPONDER and produces an OUTPUT suitable for feeding to a display system. A responsor is usually combined in a single unit with an INTERROGATOR which sends out the PULSE that triggers a TRANSPONDER, the combined unit being called an inter­rogator-responsor.

The process of determining the true plani­metric position of objects whose images appear on photographs. Restitution corrects for distortion resul­ting from both tilt and relief displacement.

A specified area designated by appropriate authority within which access or navigation is restricted in accordance with certain specified conditions.

A retracing on the GROUND of the lines of an earlier SURVEY, in which all points of the earlier SURVEY that are recovered are held fixed and used as a control. If too few points of the earlier SURVEY are recovered to satisfy the control requirements of the resurvey, a new survey may be made. A resurvey is related directly to an original SURVEY although several resurveys may interpose between them.