Systematic approach for thermal imaging camera calibration for machine vision applications

In order to estimate the intrinsic and extrinsic parameters of a camera, the geometric calibration method for a camera is required to map 3D world coordinate points onto 2D image coordinate points. In this work, a systematic approach for designing a calibration board is proposed to calibrate the thermal imaging cameras that include both mid-wave and long-wave infrared waveband (MWIR and LWIR). The low-cost materials such as thermocol, white glue, and aluminum foil sheet are used for our calibration board design and these materials have not been used for calibrating thermal cameras to the best of our knowledge. To achieve geometric calibration of thermal cameras, our calibration board has generated strong thermal image contrast and has displayed consistent checkerboard corner detection. The proposed method is tested in both indoor and outdoor environments with MWIR and LWIR cameras. The single camera calibrator tool and stereo camera calibrator tool in MATLAB are used for this work and it exhibited that the overall mean reprojection error was <= 0.40 pixel. The new board's thermal imaging quality is compared to an existing paint-based calibration board. In terms of precision, low-cost construction and easy reusability, the proposed calibration board is proven to be more beneficial.