Scale uncertainty compensation for the problem of object's geometry estimations by means of its optical image approximation with subpixel accuracy

A solution for the estimation of an unknown scale of the optical image is presented. The method does not require any scale reference or additional depth sensing apparatus other than a conventional digital camera. The estimation is performed by the multiparametric model approximation of the image acquired. A proposed image model introduces the ability to estimate the image scale by means of preliminary calibrated dependence of optical system's spread function with respect to the image scale. The key feature of the method is the fast image simulation of a freeform object with subpixel accuracy by approximated analytical calculation of its Fourier transform.