Current aircraft have a requirement to operate at night and in adverse weather where optical imaging systems are inoperable. Imaging sensors operating at other wavelengths have the potential to provide vision through severe weather, but these systems need to be simulated before assuming the technological and financial risks involved in hardware development. Sensor and atmospheric models have been developed which simulate images at a variety of wavelengths. These models have been incorporated into a modified version of the IVEX Corporation Behold software which is used for the creation of three dimensional views of terrain data bases and includes fractal texturing and anti-aliasing. This new version, called Behold-ms, adds phenomenological models of material properties, such as surface roughness, emissivity, and temperature, and structured atmospheric weather models that consider path emission, backscatter, and specular/diffuse reflections of the sky. To date, images have been simulated in the visible (color), infrared (8-14pm), passive millimeter wave (35 GHz and 95 GHz), and active MMW (35 GHz and 95 GHz). These algorithms can be used for other windows over this spectral range. In order to accommodate the widely varying types of sensed energy while maintaining a practical amount of internal storage, a scheme for scaling each spectral band has been developed. Spatial resolution degradation due to diffraction, which is especially important at millimeter wavelengths, spatial sampling effects, and system noise models are also included. These sensor models and simulations have been used to examine adverse weather landing systems. Simulated images have also been used in image understanding research and spatial superresolution studies.