The capability of accurately modeling a wide, range of military targets, in both the RF and IR portion of the spectrum, has become essential for the numerous defense programs associated with tactical weapon sensors and satellite surveillance systems. Advances in computer technology permit the use of precise analytical models early in the development cycle of new sensors. This capability leads to a new class of methods for synthetic sensor performance verification. Having recognized this opportunity Aerojet ElectroSystems Company (AESC) has developed techniques for passive target signature modeling in the 1 to 25 μm region. This paper summarizes the company's approach to passive three dimensional target modeling.