System and methods for shape measurement using dual frequency fringe pattern

Abstract

A method obtains the shape of a target by projecting and recording images of dual frequency fringe patterns. Locations in each projector image plane are encoded into the patterns and projected onto die target while images are recorded. The resulting images show the patterns superimposed onto the target. The images are decoded to recover relative phase values for the patterns primary and dual frequencies. The relative phases are unwrapped into absolute phases and converted back to projector image plane locations. The relation between camera pixels and decoded projector locations is saved as a correspondence image representing the measured shape of the target. Correspondence images with a geometric triangulation method create a 3D model of the target. Dual frequency hinge patterns have a low frequency embedded into a high frequency sinusoidal, both frequencies are recovered in closed form by the decoding method, thus, enabling direct phase unwrapping.