Typical inventive practice provides for electronic communication of a computer with a display, an active radar device (for transmitting target-location data and environmental data), a light measurement device (for transmitting visual light data), and passive imaging devices covering bands in the visual, infrared (MWIR and/or LWIR), and millimeter wave regions of the electromagnetic spectrum. Inventive software in the computer's memory establishes “operational modes.” Each operational mode is defined at least by a predominant environmental (obscuration and lighting) character, ascribes “modal indices” to individual imaging devices, and carries its own multispectral image fusion algorithm (which, pursuant to the ascribed modal indices, attributes weights to the imaging data from the respective imaging devices). The inventive software aims the imaging devices toward the target, selects an operational mode (based on the environmental data), and executes the image fusion algorithm associated with the selected operational mode so that a fused multispectral image is displayed.