High dynamic range fringe acquisition: A novel 3-D scanning technique for high-reflective surfaces

This paper presents a novel 3-D scanning technique for high-reflective surfaces based on phase-shifting fringe projection method. High dynamic range fringe acquisition (HDRFA) technique is developed to process the fringe images reflected from the shiny surfaces, and generates a synthetic fringe image by fusing the raw fringe patterns, acquired with different camera exposure time and the illumination fringe intensity from the projector. Fringe image fusion algorithm is introduced to avoid saturation and under-illumination phenomenon by choosing the pixels in the raw fringes with the highest fringe modulation intensity. A method of auto-selection of HDRFA parameters is developed and largely increases the measurement automation. The synthetic fringes have higher signal-to-noise ratio (SNR) under ambient light by optimizing HDRFA parameters. Experimental results show that the proposed technique can successfully measure objects with high-reflective surfaces and is insensitive to ambient light.

► The main innovation of the technique is the high dynamic range fringe acquisition (HDRFA).
► This creates a new fringe image free from saturation and darkening by fusing several different raw fringe images.
► Fringe image fusion algorithm based on masks, related to phase-shifting algorithms is introduce, which meets the demands.
► A method of auto-selection of HDRFA parameters is developed and largely increases the measurement automation.
► The proposed technique is insensitive to ambient light.