The next generation of weapons systems will benefit from an array of new technologies which, when integrated, will provide the capability of accurately selecting the correct target. For example, target image features can be extracted from high resolution satellite data and this information can be fused with feature positions obtained from a weapon's imaging sensor. This will allow automatic target recognition to be performed. Terrain aided localization using electro-optical sensing (TALEOS) is a robust method of enhancing the performance of an imaging system through the exploitation of other sources of information. The primary image processing technique used in TALEOS is model-matching. The objective of model-matching is to discover the 3D position and orientation of an object (the model) with respect to the sensor reference frame by performing a match with corresponding features. In TALEOS, the model is derived from remotely sensed data and contains information about potentially observable features which might be extracted from the image. Embedded in this extended model is information about specific targets, including their known or estimated position, and features which characterize them. The Sowerby Research Center terrain model facility was used to gather realistic imagery. The terrain model is a 300:1 scale model of a 25 square kilometer area of real terrain. An overhead gantry system carries a video camera over the model enabling a wide variety of flight scenarios to be simulated experimentally. By a combination of special paint schemes and video inversion, pictures of the terrain model can provide a realistic simulation of infrared imagery. An image database was simulated using an overhead view of the model as if seen from a 'satellite' or reconnaissance aircraft. This imagery was utilized to evaluate the performance of the TALEOS technique for comparison with theoretical results. TALEOS integrates the data from the image processing subsystem with data from a (modeled) inertial navigation system, using a Kalman filter, to generate the position of the sensor relative to the target. This paper describes TALEOS. The principles of these technologies are described and test results presented. Possible future developments are discussed.