Extrinsic Parameters Calibration Method of Cameras with Non-Overlapping Fields of View in Airborne Remote Sensing

Lei Yin,Xiangjun Wang,Yubo Ni,Jilong Zhang,Kai Zhou

doi:10.3390/rs10081298

Abstract

Multi-camera systems are widely used in the fields of airborne remote sensing and unmanned aerial vehicle imaging. The measurement precision of these systems depends on the accuracy of the extrinsic parameters. Therefore, it is important to accurately calibrate the extrinsic parameters between the onboard cameras. Unlike conventional multi-camera calibration methods with a common field of view (FOV), multi-camera calibration without overlapping FOVs has certain difficulties. In this paper, we propose a calibration method for a multi-camera system without common FOVs, which is used on aero photogrammetry. First, the extrinsic parameters of any two cameras in a multi-camera system is calibrated, and the extrinsic matrix is optimized by the re-projection error. Then, the extrinsic parameters of each camera are unified to the system reference coordinate system by using the global optimization method. A simulation experiment and a physical verification experiment are designed for the theoretical arithmetic. The experimental results show that this method is operable. The rotation error angle of the camera’s extrinsic parameters is less than 0.001rad and the translation error is less than 0.08 mm.

Highlights

Photogrammetry is widely used in aerial remote sensing [1,2,3]
We propose a flexible multi-camera calibration method without common field of view to be used in an airborne remote sensing field
Experiments show that the optimization method based on the projection error effectively improves the accuracy of the linear solution in binocular calibration

Summary

Introduction

Photogrammetry is widely used in aerial remote sensing [1,2,3]. More and more airborne remote sensing platforms are equipped with multi-camera systems to complete tasks such as image mosaic [4], terrain reconstruction [5,6] and monitoring [7,8,9]. In some multi-camera remote sensing photography systems, the angle between the optical axes of the cameras is large enough to obtain a large field of view (FOV), resulting in the non-overlapping of the FOV, and increasing the calibration difficulty of extrinsic parameters. The quality of terrain reconstruction and panoramic mosaic tasks depend on the accuracy of the camera extrinsic parameters. To solve this problem, we introduce a universal multi-camera extrinsic calibration method without common FOVs. The commonly used method for calibrating the extrinsic parameters is based on a two-dimensional target proposed by Zhang Z [10]. The above method requires that the different cameras must have overlapping FOV, and the traditional calibration method is no longer applicable when the cameras have no common FOV, because the same target cannot be observed by different cameras

Methods

Results

Discussion

Conclusion