Geo-Pointing and Threat Location Techniques for Airborne Border Surveillance

A mathematical method for geo-pointing an airborne surveillance imager to defined ground borders is developed. Further, equations for geo-location of imaged artifacts for situational awareness and security response are presented. Border patrol using electro-optical, RF, or other wavelength surveillance imagers on airborne platforms calls for autonomous control of Line of Sight (LOS) position. Using inertially stabilized gimbals, imagers have the capacity to not only reject motion disturbances, but also direct their LOS in an inertial coordinate frame. This capability allows for automatic pointing of the imager's LOS to defined ground areas. While autonomous geo-pointing and geo-location functions for consistently nadir looking imaging is trivial, the solution for imaging at standoff distances is not. The developed approach enables autonomous imaging of defined ground areas at arbitrary standoff distances without the need for range finding instrumentation. This is advantageous to security missions by allowing for discrete and safer surveillance. On board microprocessors can execute real time computation of pointing vectors using platform INS/GPS information along with mapped coordinates. Automatic surveillance of borders at standoff distances becomes possible then by mathematics that considers Earth's geometry, the platform's position, and border coordinates. The developed method solves for LOS pointing vectors in inertial coordinates, which can be utilized directly to geo-point inertially stabilized imagers. Information from the system's inertial sensors is tagged to image data and used to geo-locate targets of interest captured by the imaging system. A solution for determining image geodetic coordinates to geo-locate potential ground threats is presented.