Abstract: To address the problems of large number of projected images and high complexity in the traditional fringe projection measurement, this paper proposes a fringe-gray linear projection strategy and phase solution method based on Hilbert transform. The proposed method simplifies the measurement process by using only three projection images:one high-frequency fringe image and two grayscale linear change maps. The wrapping phase is obtained by the Hilbert transform, and the basic phase is obtained by using the grayscale linear change image. By combining the wrapping phase and the basic phase, the absolute phase, which represents the fringe progression, can be obtained. The 3D reconstruction results obtained by the constructed active binocular system shows that the proposed method can effectively restore the 3D shape of the measured object, with a measurement accuracy of 0.1 mm.

Key words: 3D measurement, fringe-gray linear projection, Hilbert transform, absolute phase, active binocular