Digital camera calibration method for close-up photogrammetry of large structures

For large structures, the current close-up photographic calibration method has difficulty meeting the requirements of large structures that fill the camera’s field-of-view. Therefore, a digital camera calibration method for close-up photogrammetry of large structures is proposed. The size of the chequerboard calibration plate is further reduced by adopting multiple shots, and the focusing distance of the camera is set to be larger than the hyperfocal distance to realise digital camera calibration for close-up photogrammetry of large structures. Additionally, validation and application experiments are designed to complete the demonstration. The results show that the proposed method can overcome the problem that the traditional camera calibration method cannot be applied to large structures. The reprojection error after using the method is significantly lower than 0.5 pixels, and the measurement accuracy is improved from the decimetre level to the millimetre level. It is shown that the method can be applied to the close-up photogrammetry of large structures such as hillsides and dams.