MEASURING METHOD FOR LENGTH OR DISTANCE AND CALIBRATION INSTRUMENT FOR THE MEASUREMENT

摘要

PURPOSE: To measure the length or distance of an objective part by setting a calibration instrument on the objective part to be measured, reading coordinate values on an image of a reference point of a flat part and an end point of a leg part of the calibration instrument, and obtaining a three-dimensional inclination of a plane of the objective part to an optical axis. ;CONSTITUTION: An optical axis of a camera is set on a Z-axis and a point C is set to be the position of a principal point. The camera apparently photographs an object from this point C. Point on a straight line drawn radially from the point C are seen from the camera to be the same point. A plane of a calibration instrument 301 where a central point C'_o is set satisfies Z=0. The camera is focused on a plane satisfying Z=Z_n and has a sufficient depth of field. A C_o is a projection of the C'_o to a focal plane seen from the camera and it is the C_o that can be observed as a coordinate value on an image of the camera. A Q_i (i=1, 2, 3) is an end of the calibration instrument 301 and a P_i (i=1, 2, 3) is a projection of the Q_i to the focal plane seen from the camera. Therefore, only the Pi can be observed on the image of the camera.;COPYRIGHT: (C)1995,JPO