Abstract: To obtain an accurate survey value even if a centering operation is simplified without using a specific target. When a survey point S is displayed on the screen of a display 20 as an image picked up by a CCD camera 38 in a process to perform an operation for placing a surveying instrument 10 directly above the survey point S, a centering operation is ended, and the survey point S is specified as a true centering point. Accordingly, coordinates (Xs, Ys) of the survey point S in which the instrument center point 0 is defined as an origin are calculated as a decentering amount (i.e., dislocation) of the survey point S with respect to an instrument center point 0.

Abstract: To obtain an accurate survey value even if a centering operation is simplified without using a specific target. When a survey point S is displayed on the screen of a display 20 as an image picked up by a CCD camera 38 in a process to perform an operation for placing a surveying instrument 10 directly above the survey point S, a centering operation is ended, and the survey point S is specified as a true centering point. Accordingly, coordinates (Xs, Ys) of the survey point S in which the instrument center point 0 is defined as an origin are calculated as a decentering amount (i.e., dislocation) of the survey point S with respect to an instrument center point 0.

Abstract: The invention relates to a method and apparatus for measuring the coordinates of a survey point. The apparatus uses a reflecting mirror at the survey point, a tachymeter for transmitting light to the reflecting mirror and for receiving light reflected from the reflecting mirror, first calculating means for calculating the coordinate values of two positions of the reflecting mirror, and second calculating means for calculating a coordinate value of the survey point from the coordinate values of the two reflecting mirror positions. In operation, the tachymeter transmits light to the reflecting mirror at the survey point wherein the reflecting mirror is locatable at two points present on a line passing through the survey point and which are separated from the survey point by predetermined distances.