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The problem of track initiation in the exoatmospheric ballistic missile defense scenario has been studied before, assuming a scanning LWIR sensor. This paper is concerned with the same problem, but under a more difficult sensor configuration, namely, a set of mid-altitude satellite sensors. To handle conditions of high target density and poor observability, a new initiation procedure is used for the iterative-least-square (ILS) filter, and the filter itself is modified to accept a-priori state covariance. The target density is effectively reduced by calling upon an edge tracker initially, which forms track files of edges of the clusters. Track initiation is then accomplished by referencing to those edge track files, assuming that targets in the same cluster travel in parallel. Tracks initiated by two sensors are merged to provide precise state estimates to the extended Kalman filter that is used to carry out the track maintenance task.

A tracking algorithm operating in a dense target environment is described. This algorithm is designed for a passive optical (angle only) sensor handling a very large number of targets. For the application considered, the sensor has limited angular resolution and the sampling rate is exceedingly low. To further complicate the algorithm design issues, the underlying system is nearly unobservable. The standard extended Kalman filter is not applicable in this case; an iterative maximum likelihood estimator must be used.