Ranging by means of monocular passive systems

In this paper we investigate on a ranging system based on the images recorded by a single passive camera. To estimate the distance from an object it is necessary to know its dimensions, so the observed target must be identified. The target is assumed to be a translated, rotated and scaled version of the corresponding reference image included in a database. The distance to the object is estimated by comparing the extracted target with its reference image taken at a known distance. We consider two different Automatic Target Recognition techniques and compare their performances on a set of simulated data. Namely we evaluate the probability of correct recognition and the relative error in distance estimation. Finally, we discuss the results obtained by processing an experimental sequence of images recorded by an IR camera.