基于光线追迹法的非均匀温度场视觉测量畸变校正

Distortion Correction of Visual Measurement in Inhomogeneous Temperature Field Based on Ray Tracing Method

为了解决视觉测量在非均匀折射率环境中应用时出现的成像畸变问题,建立了在非均匀温度场中形成的非均匀折射率场,研究了光线在该折射率场中的轨迹并根据轨迹偏差修正了图像畸变。利用背景纹影法重构了由非均匀温度场产生的空间折射率场,将空间点发出的光抽象为光线,根据龙格-库塔法修正非均匀折射率场中的光线轨迹并校正图像畸变。利用PnP(pespective-n-point)算法和校正前后图像中同一点的像素坐标解算该点的世界坐标。实验结果表明,该方法能有效降低测量误差,修正被测图像的畸变。

In this study, to address the issue of imaging distortion that occurs when visual measurements are applied in inhomogeneous refractive index environments, an inhomogeneous refractive index field produced in the inhomogeneous temperature field is developed, and the trajectory of light in the refractive index field is investigated, and the image distortion is corrected according to the trajectory’s deviation. The spatial refractive index field produced using the nonuniform temperature field is reconstructed using the background schlieren method. The light emitted by the spatial point is abstracted as light rays and reproduces the light in the inhomogeneous temperature gradient environment according to the Runge-Kutta method. The world coordinates of the point are computed based on the PnP(perspective-n-point)algorithm and the pixel coordinates of the same point in the image before and after correction. Experimental findings demonstrate that the method can efficiently decrease the measurement error and correct the measured image’s distortion.