"Method for large-scale structured-light system calibration," Optics Express (2021)

A. G. Marrugo, R. Vargas, L. A. Romero, and S. Zhang,  "Method for large-scale structured-light system calibration," Optics Express, 29(11), 17316-17329 (2021); doi:10.1364/OE.422327

Abstract

We propose a multi-stage calibration method for increasing the overall accuracy of a large-scale structured light system by leveraging the conventional stereo calibration approach using a pinhole model. We first calibrate the intrinsic parameters at a near distance and then the extrinsic parameters with a low-cost large- calibration target at the designed measurement distance. Finally, we estimate pixel-wise errors from standard stereo 3D reconstructions and determine the pixel-wise phase-to-coordinate relationships using low-order polynomials. The calibrated pixel-wise polynomial functions can be used for 3D reconstruction for a given pixel phase value. We experimentally demonstrated that our proposed method achieves high accuracy for a large volume: sub-millimeter within 1200(H) \times 800 (V) x 1000(D) mm^3.

"Flexible and high-accuracy method for uni-directional structured light system calibration," Optics and Lasers in Engineering (2021)

S. Zhang,  "Flexible and high-accuracy method for uni-directional structured light system calibration" Optics and Lasers in Engineering, 143, 106637 (2021)

Abstract

This paper presents a novel method that can accurately calibrate structured light system requiring only one directional structured patterns. This method leverages the existing flexible camera calibration to extract each calibration pose for three-dimensional coordinate determination for each pixel, and then establish pixel-wise relationship between each coordinate and phase. The phase artifacts caused by high-contrast calibration target was addressed to eliminate its impact on the calibration. Comparing with the traditional structured light system calibration method that requires two directional fringe patterns, our method requires only one single directional fringe patterns yet achieves 6.6 times higher accuracy for flat surface measurements.

"Comparative study on 3D optical sensors for short range applications", Optics and Laser Technology (2021)

Abstract

The increasing availability of commercial 3D optical sensors drastically benefits the mechatronics community by providing affordable sensing means for perception and control. Yet, to our knowledge, there are no comparable study to the state-of-the-art 3D optical sensors, making it difficult for users to select for their specific applications. This paper evaluates the performance of each sensor for short range applications (i.e., $\le$  1 m ). Specifically, we present our findings on the measurement accuracy of each sensor under ``ideal'' situations, compare the influence of various lighting conditions, object surface properties (e.g., transparency, shininess, contrast), and object locations. In addition, we developed software APIs and user instructions that are available for the community to easily use each of the evaluated commercially available 3D optical sensor.

Vide associated with submitted manuscript is below