Dynamics range enhancement in digital fringe projection technique

• This paper is proposing a new technique to enhance dynamic range of fringe projection profilometry systems called spatially varying pixel intensity (SVPI) technique.
• The goal of SVPI technique is to control the irradiance of each pixel on the camera by repeatedly adjusting the intensity of the projection pattern at pixel level.
• This technique is uniquely suitable for profilometry of objects with wide range of variation in their optical reflectivity.
• The proposed technique is verified by both simulation and experiment.

In this paper a new approach to enhance the dynamic range of a fringe projection system for measuring 3D profile of objects with wide variation in their optical reflections is proposed. The high dynamic range fringe images are acquired by recursively controlling the intensity of the projection pattern at pixel level based on the feedback from the reflected images captured by the camera. A four step phase shifting algorithm combined with a quality guided algorithm is used to obtain the unwrapped phase map of the object from the acquired high dynamic range fringe images. Simulation and experimental results show that the proposed technique can accurately measure the 3D profile of objects with wide variation in their optical reflectivity.