METHOD FOR RECOGNIZING OBJECT

PURPOSE:To recognize a three-dimensional shape with simple processing and composition by switching the depth of focus of an image pickup means and storing an image at a part in which the difference in the lightness of a picture is closed to zero as contour line information. CONSTITUTION:A focal length L of an ITV camera 2 is set to a scanning start distance by a control signal from a picture processor 5, and next, variables to indicate a scanning space, the number of the times of scanning, a threshold value, and the current number of the times of scanning are set. Next, the focal length is changed by a switching mechanism 3, and the depth of focus is changed by a switching mechanism 4, respectively. Thus, in the camera 2, the depth of focus is either deepened or shallowed, and respective received pictures are stored in the memory of the device 5. At this time, the device 5 calculates the differences in the lightness of picture elements corresponding to the respective pictures, determines some picture elements at parts in which the differences are smaller than the threshold value determined from a zero point as the picture elements at the position of a contour line, links the picture elements at the position of the contour line with each other, and stores the linked picture elements as contour line information 6. Further, after the whole of the scanning of an object 1 completes, the three-dimensional shape of the object 1 is recognized from the bent state and the interval of the information 6.