Target Analysis for the Multispectral Geometric Calibration of Cameras in Visual and Infrared Spectral Range

While for the geometric calibration of cameras in the visual spectral range simple printed targets with chessboard patterns have become established over the years, the spectrum of targets used for cameras in the infrared range is broadly diversified. Within the scope of this article different target types are compared with each other in the four spectral ranges visual (VIS), near infrared (NIR), medium-wave infrared (MWIR) and long-wave infrared (LWIR). For this purpose, three targets are manufactured and evaluated with regard to the detectability of the features and the achievable calibration results. The use of a single target, which provides good results in all ranges, is of particular interest for the extrinsic calibration of cameras of different wavelengths to each other. It is shown that the contrast-to-noise ratio and different OpenCV feature detection algorithms are the reasons for the varying calibration quality with different targets.