| 摘要 |
PROBLEM TO BE SOLVED: To precisely determine the center-of-gravity coordinate of a planer pattern projected in a photographed image to improve the precision of photographic surveying. SOLUTION: The image of a disc 20a is formed on the imaging surface 14a of an image pickup element 14 by the photographic optical system 12 of a camera 10 to provide a photographic image. This center-of-gravity coordinate calculating device reads the photographic image and calculates the relative positions of the plane H including the disc 20a to a rear main point position FC and the center SC of the disc 20a. A light Ln is emitted from the first corresponding point Kn of the imaging surface 14a, and the intersection of the light Ln with the plane H including the disc 20a is determined as the second corresponding point Sn. The angleθ1n formed by the light Ln and the normal of the plane H, the angleθ2n formed by the light Ln and the optical axis LB, and the distance Zn in the optical axial direction between the rear main point position FC and the second corresponding point Sn are calculated, and weighing is performed for each picture element in the area corresponding to the disc 20a to calculate the center-of-gravity coordinate.
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