1. A three dimensional contour measuring system for measuring and recording the contour of a three dimensional object comprising an encoder for measuring the distance between adjacent moire fringes of a moire obtained by the interference between a standard grating and a deformed image of a standard grating deformed by the surface of a three dimensional object, a computer connected with said encoder for calculating the depth or height of a point on the object on one moire fringe with respect to the depth or height of a point on the object on the moire fringe adjacent to said one moire fringe, signal input means provided in said computer for input of a signal which indicates whether the surface of the object represented by the moire fringes is convex or concave, magnification input means provided in said computer for input of a signal which indicates the magnification of an optical system for projecting the image of the standard grating on the surface of the object, and an X-Y recorder connected with said computer for recording the output of the computer, whereby said X-Y recorder records the contour of the three dimensional object and said computer computes the cross-sectional area and the cross-sectional line length of the object.