A capability for generating sky images containing both clouds and aircraft has been developed through concatenating a variety of models and matting theim to an Image Array Processor. A family of apparent images are generated, each at a specific wavelength, whose gray scale values are in terms of absolute radiometric units. These images can then be combined as weighted sums to represent the appropriate spectral distributions for a specific sensor of interest. For example, this simulator has been used to generate sky scenes as inputs to a color CCD camera emulation.
George A. Hoffman,
"Aircraft & Cloud Sky Simulator", Proc. SPIE 0933, Multispectral Image Processing and Enhancement, (24 August 1988); doi: 10.1117/12.968474; https://doi.org/10.1117/12.968474