Method for eliminating error in camera having angular velocity detection system
An error in a camera having angular velocity sensors is eliminated. A camera is placed on a rotating table and rotated, angular velocities are detected by angular velocity sensors, and a CZP chart is photographed. The motion of the camera is computed as a locus of motion of a point light source on an imaging plane from the outputs from the angular velocity sensors. The inclination of the locus motion is compared with the inclination of a zero-crossing line which has been obtained by subjecting the photographed image to Fourier transformation, to thus compute angles of relative inclination of the angular velocity sensors with respect to the image sensor. Further, when no coincidence exists between the zero-crossing line of the data into which a PSF has been Fourier-transformed and a zero-crossing line of the data into which a photographed image has been Fourier-transformed, a computer computes a correction coefficient from a proportion of an interval between the zero-crossing lines, on condition that an error is included in the angular velocity sensors or the focal length of a photographing lens, and the error is eliminated.
1. A method for eliminating an error in a camera having an angular velocity detection system, the method comprising:
rotating the camera around a reference axis;
acquiring an image while rotating the camera around the reference axis;
computing motion of the camera as a locus of motion of a point light source on an imaging plane, from an output of angular velocity from the angular velocity detection system acquired when the camera has been rotated around the reference axis; and
eliminating a plurality of errors included in the output of angular velocity and a photographing lens system, on the basis of the image and the locus of motion;
wherein the step of elimination includes the steps of:
computing inclination of the locus of motion;
calibrating the output of angular velocity on the basis of the inclination;
computing a point spread function (PSF) from a calibrated locus of motion;
subjecting the PSF to Fourier transformation; and
comparing a zero-crossing point of data into which the PSF has been Fourier-transformed with a zero-crossing point of data into which the image is Fourier-transformed.
2. The method for eliminating an error in a camera having an angular velocity detection system according to claim 1 , wherein the step of calibration includes computing a correction coefficient C by C =b/a by means of a plurality of error coefficients C, provided that a width of the zero-crossing point of data acquired by Fourier transformation of the PSF is taken as “a” and the width of the zero-crossing point of data acquired by Fourier-transformation of the photographed image of a circular zone plate chart is taken as “b”.