Dynamic 3D Measurement without Motion Artifacts Based on Feature Compensation.

Phase-shift profilometry (PSP) holds great promise for high-precision 3D shape measurements. However, in the case of measuring moving objects, as PSP requires multiple images to calculate the phase, the movement of the object causes artifacts in the measurement, which in turn has a significant impact on the accuracy of the 3D surface measurement. Therefore, we propose a method to reduce motion artifacts using feature information in the image and simulate it using the six-step term shift method as a case study. The simulation results show that the phase of the object is greatly affected when the object is in motion and that the phase shift due to motion can be effectively reduced using this method. Finally, artifact optimization was carried out by way of specific copper tube vibration experiments at a measurement frequency of 320 Hz. The experimental results prove that the method is well implemented.

Vision measurement error analysis for nonlinear light refraction at high temperature.

For vision measurement at high temperature, pixel error from light refraction by high temperature is a problem that cannot be neglected. The refractive index distribution is nonlinear around the high-temperature component, leading to the light deflection. In this paper, the influence of measurement parameters on the deflection of imaging light and the accuracy after binocular reconstruction are systematically analyzed. The heat transfer theory is used to simulate the air temperature distribution near the measured component, and the corresponding refractive index distribution of air is obtained according to the refractive index formula. Then, the imaging measurement model of the nonlinear refractive index air medium for the high-temperature component is established to obtain the light deflection error. The binocular vision system reconstruction theory is applied to evaluate the measurement error between the theoretical reconstruction point and the object point. The influences of error sources, such as the temperature, optical wavelength, and camera parameters, are investigated systematically. It is found that temperature and base distance are the largest error sources on the final measurement error when the measured distance is fixed.