Patent ID: 7616806

Claim:
An apparatus for detecting a position in an actual space of an object by imaging said object with an imaging unit, comprising: said imaging unit for obtaining an image of a plurality of objects; a position-in-image calculating unit for calculating respective projected coordinates x 1 * and x 2 * of a first object and a second object in said image obtained by said imaging unit, said first and second objects being separate from each other and arranged in an actual space with coordinates (Xn, Zn) and (Xn−D, Zn) so that said first and second objects are away from said imaging unit by a distance Zn and that said first object is away from said second object by a distance D, where said coordinate Xn is arbitrary; and a corrective coefficient calculating unit for calculating a corrective coefficient c to correct a design parameter F of said imaging unit, wherein said corrective coefficient calculating unit calculates a coordinate x 1 in said image of a design position of said first object and a coordinate x 2 in said image of a design position of said second object by using the design parameter F determined based on a design focal length (f) of the imaging unit and a design pixel pitch (p) of the imaging unit and equations: x 1= F·Xn/Zn x 2= F ·( Xn−D )/ Zn and then said corrective coefficient calculating unit calculates said corrective coefficient α by equations: α· x 1*= x 1 α· x 2*= x 2 using said coordinates x 1 and x 1 * and said coordinates x 2 and x 2 *, and wherein said design parameter F is corrected to be 1/α·F with said corrective coefficient α, and said projected coordinates of said objects imaged by said imaging unit are corrected.