An Exposure Fusion-Based Structured Light Approach for the 3D Measurement of a Specular Surface

Reflection happening on a specular surface severely degrades the performance of structured light-based 3D measurements. Traditional structured light techniques remain limited to ideal scenes. Inspired by the multiple exposure fusion technique in photography, which fuses a number of exposure sequences into a well-exposed image, we propose an exposure fusion (EF)-based structured light method in this work. With well-exposed images, the brightness difference of the specular surface can be reduced. Binary gray code is adopted as the primary structured light pattern. With the help of the EF technique, the generated well-exposed structured light images are used for 3D reconstruction of the specular surface. To evaluate the performance of our method, the defective batteries with reflective properties are tested in this experiment. The high dynamic range (HDR)-based structured light method, auto-HDR and ABFDP methods are introduced for comparison. In these experiments, an average error of 0.088 mm and a standard deviation of 0.1921 mm are obtained. These results show that the EF method performs better than other methods for the reconstruction of specular surfaces and can be used to distinguish defects on the surface of a battery.