Abstract: A method of and a system for tracing a monochromatically contrasting pattern on a uniplanar surface, in which signals indicative of a detected image of the pattern are produced by photoelectric transducer elements arranged in a two-dimensional or linear matrix array and signals indicative of a suitable number of modified reference areas displaced a predetermined distance from a prescribed basic reference area formed on a plane parallel with the uniplanar surface are produced from memory units having the modified reference areas registered therein, whereupon signals indicative of areas over which the detected image sensing zone is overlapped by the modified reference areas are produced to determine the direction in which the matrix array is to be moved with respect to the pattern on the uniplanar surface.