Electro-optical target and background simulation

An electro-optical target and background simulation system for generating synthetic images, said system comprising:

• a background database from which a simulated background is generated and which comprises data defining an image scene that comprises a pyramid whose boundary specifies the extent of the image scene, and wherein the pyramid is divided into a pyramid base defining a below horizon background surface and pyramid sides defining an above horizon background surface, and wherein each surface comprises triangular regions of uniform texture;
• a target database comprising a plurality of triangular object facets representative of simulated objects that are adapted to overlay the background generated from the background database;
• and
• processing means coupled to the background and target databases for processing data derived therefrom and for generating the synthetic images, and wherein the processing means comprises:
• radiance mapping means for processing data indicative of seeker operating frequency bands and for determining the radiance of each target facet that forms the target, plume point radiance, mean radiance values for background regions, sun position, and atmospheric conditions, for providing an output comprising a surface radiance map of the image scene;
• coordinate transformation means for processing data indicative of target and missile center-of-mass positions and orientations and for providing an output comprising a three dimensional seeker image frame
• shadowing means that determines shadowed areas on an object because the surface is not oriented toward the sun or because the surface is obscured by another portion of the same object, and that computes a dot product between a facet normal and a vector to the sun or seeker to determine if the facet is oriented toward the sun or seeker and hence is shadowed or obscured;
• hidden surface removal means that removes object facets obscured from the view of the seeker because the surface is not oriented toward the seeker, or because the seeker is obscured by another portion of the same object, and that compares the facets with each other to determine if the facet is shadowed or obscured;
• perspective projection means for generating a two dimensional image plane by perspective three dimensional mapping from the background and target databases to a focal plane of the seeker;
• atmospheric attenuation and scattering means for processing atmospheric data to determine its effect on the radiant intensity of the background and target and for modifying the image in response thereto;
• and
• optical convolution means for generating a two dimensional image on the focal plane of the seeker by convolving a projected image with an optical point spread function of the seeker to generate a radiance distribution on the focal plane of the seeker, which radiance distribution comprises the synthetic image.

A computer-implemented electro-optical target and background simulation method for generating synthetic images, said method comprising the steps of:

• generating a background database comprising data defining an image scene that comprises a pyramid whose boundary specifies the extent of the image scene, and wherein the pyramid is divided into a pyramid base defining a below horizon background surface and pyramid sides defining an above horizon background surface, and wherein each surface comprises triangular regions of uniform texture;
• generating a target database comprising a plurality of triangular object facets representative of simulated objects that are adapted to overlay the background generated from the background database;
• processing data derived from the background and target databases for generating the synthetic images that facilitate the design and test of an electro-optical seeker located on a missile, in accordance with the steps of:
• processing data indicative of seeker operating frequency bands and for providing a surface radiance map of the image scene;
• processing data indicative of target and missile center-of-mass positions and orientations in world coordinates and for providing a three dimensional seeker image frame;
• processing seeker field of view data to clip the image to the extent of the seeker field of view;
• determining shadowed or obscured areas on an object by computing a dot product between the facet normal and the vector to the seeker to determine if the object is shadowed or obscured;
• removing object facets obscured from the view of a seeker due to shadowing or obscuration;
• generating a two dimensional image plane by perspective three dimensional mapping from the scene database to a focal plane of the seeker;
• generating a two dimensional image on the focal plane of the seeker by convolving the projected image with an optical point spread function of the seeker to generate a radiance distribution on the focal plane of the seeker, which radiance distribution comprises the synthetic image.