Patent ID: 7370363

Claim:
An aerial electronic map information creation processing method for embedding predetermined electronic map information in measured geodetic coordinate data of point group state as electronic watermark data, in which an aircraft installed with a laser scanner, a GPS receiver, and a gyroscope are allowed to fly over an area to collect original random point data of the area, said laser scanner being installed such that an axis of rotation of a scanning mirror of said laser scanner is perpendicular to direction of flight of said aircraft and direction of flight of said aircraft coincides with another scanning line of said scanning mirror, said GPS receiver carrying out reference point measurement is according with a GPS radio wave, a laser irradiating angle of every pulse of laser beam irradiated from the laser scanner being obtainable from said gyroscope; 3-dimensional data of ground level are measured by the irradiation of the pulse laser beam to the ground from said laser scanner; and said geodetic coordinate data of irregular point group state consisting of three coordinates (x, y, z) are obtained by converting said 3-dimensional data of the ground level into said geodetic coordinate data based on spatial position data of the aircraft obtained by said reference point measurement and said laser irradiating angle obtained by said gyroscope, comprising the steps of: a first step of carrying out a discrete Fourier transform with respect to factors of x and y coordinate values extending from said geodetic coordinate data of a point group state to obtain data, which are vertexes arranged as Ck=xk+jyk in one dimension, in order to produce a one dimensional complex Fourier coefficient sequence; a second step of modifying said Fourier coefficient sequence in accordance with said electronic watermark data to produce a watermarked Fourier coefficient sequence; and a third step of carrying out an inverse discrete Fourier transform with respect to said watermarked Fourier coefficient sequence to produce a watermarked geodetic electronic data on the basis of said inverse discrete Fourier transform.