This paper describes the generation of synthetic, large array, digitized, two-dimensional in-band radiance scenes for below the horizon (BTH) and above the horizon (ATH) viewing. A generated BTH scene for the case of multilevel clouds over an ocean-terrain interface includes edge effects. Edge geometry is specified from a large FOV visible photograph. Mean values of in-band radiance are determined from a radiation transport code. Fine-scale structure is added from prescribed statistics. The phenomenology base includes sun scattering and thermal emission effects for clouds and ground. A typical ATH irradiance scene in-band for a low threshold detector contains the earth's limb contribution and, shining through the limb, a few high threshold catalog stars and high density, weak, randomly generated stars. One-dimensional iterative and analytic statistical models are presented and compared with data for, respectively, (1) a detected radiance trace and (2) the standard deviation of the radiance and for power spectral densities of particular scene types. The analytic PSD models are a superposition of Wiener spectra, each of whose asymptotic forms is a power law of frequency to the minus two power.

Date Published: 17 December 1980
PDF: 15 pages
Proc. SPIE 0253, Modern Utilization of Infrared Technology VI, (17 December 1980); doi: 10.1117/12.959503

Published in SPIE Proceedings Vol. 0253:
Modern Utilization of Infrared Technology VI
Irving J. Spiro, Editor(s)