The project includes a single scientific activity in the form of a research internship at the National Technical University of Athens. The scientific activity planned to be carried out intends to determine the susceptibility of geometric and radiometric calibration methods of single-camera and multi-camera non-metric optical systems to varying illumination spectrum and intensity. Special attention will be given to the verification of the research hypothesis on the sensitivity of known non-metric camera calibration methods to incomplete illumination spectrum and low illumination intensity. The research plans to use empirical data recorded during measurement sessions by various optical systems popularly used in low-altitude photogrammetry and remote sensing, such as single-camera, five-camera and ten-camera systems with different optics and light-sensitive sensors. Based on the research, it will be possible to identify the optimal measurement conditions and artificial illumination spectrum for performing such calibration and develop a new calibration method that takes into account the variable and incomplete illumination spectrum of the scene. In this way, it will be possible to develop new correction coefficients for internal orientation elements of cameras and distortion parameters, taking into account the leading spectrum of scene illumination and, as a result, to achieve higher accuracy of development than before. This is important because the existing illumination, especially low intensity illumination, causes errors in determining the internal orientation elements and distortion parameters of non-metric camera already at the initial stage of measurement data processing. This error accumulates in the numerical process and significantly affects the final result. As it has already been shown in preliminary studies, in some cases the error values are so high that the products of photogrammetry and remote sensing do not meet the accepted standards of processing. It should be noted that the sensitivity of the applied calibration methods, described here, is a phenomenon so far unnoticed in modern digital photogrammetry and low-level remote sensing.