Three-Point Marking Method to Overcome External Parameter Disturbance in Stereo-DIC Based on Camera Pose Self-Estimation

Chang Ma,Xiaobo Rui,Zhoumo Zeng,Hengrui Cui,Hui Zhang

doi:10.1109/access.2020.3017236

Chang Ma, Xiaobo Rui + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.3017236

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Abstract

Stereo digital image correlation (stereo-DIC) requires the stereo-camera system to remain fixed during the measurement process. This requirement brings a lot of inconvenience to the practical application of stereo-DIC. In many application scenarios such as dynamic measurement, the external parameters of the camera are almost inevitably disturbed, which will bring great errors to the DIC measurement results. To overcome this problem, this paper proposes a three-point marking method to determine the world coordinate system and a camera pose self-estimation method based on speckle patterns. The three-point marking method can use three undeformed feature points in the field of view (FOV) to determine the world coordinate system. The proposed camera pose self-estimation method can calculate the pose parameters of the binocular camera at the shooting time of each frame of image. This method does not require plane assumptions and has good applicability. Simulations and experiments were carried out to verify the effectiveness of the proposed scheme in overcoming external parameter disturbances.

Highlights

Digital image correlation (DIC) is an optical measurement method that measures the displacement and strain fields of an object due to deformation
This paper proposes a three-point marking method for setting the world coordinate system and a camera pose selfestimation method based on speckle patterns
In addition to the problem of setting the world coordinate system, to overcome the disturbance of the external parameters of the camera, it is necessary to make the DIC have the function of camera pose self-estimation

Summary

INTRODUCTION

Digital image correlation (DIC) is an optical measurement method that measures the displacement and strain fields of an object due to deformation. They proposed an automatic calibration method based on the speckle pattern on the surface of the measured object, which effectively overcome the limitations of the traditional calibration method They adopted a real-time optimization method to reduce the impact of external parameter disturbances on measurement accuracy. In addition to the problem of setting the world coordinate system, to overcome the disturbance of the external parameters of the camera, it is necessary to make the DIC have the function of camera pose self-estimation. The proposed method only needs a pair of images of binocular view, and there is no plane assumption, that is, the surface of the object to be measured does not need to be flat It has strong applicability and can provide stable and reliable external parameters.

SELF-ESTIMATION METHOD OF CAMERA POSE

SIMULATION OF STEREO-DIC WITH EXTERNAL PARAMETERS DISTURBED

CONCLUSION