SAR ATR using a modified learning vector quantization algorithm

We addressed the problem of classifying 10 target types in imagery formed from synthetic aperture radar (SAR). By executing a group training process, we show how to increase the performance of 10 initial sets of target templates formed by simple averaging. This training process is a modified learning vector quantization (LVQ) algorithm that was previously shown effective with forward-looking infrared (FLIR) imagery. For comparison, we ran the LVQ experiments using coarse, medium, and fine template sets that captured the target pose signature variations over 60 degrees, 40 degrees, and 20 degrees, respectively. Using sequestered test imagery, we evaluated how well the original and post-LVQ template sets classify the 10 target types. We show that after the LVQ training process, the coarse template set outperforms the coarse and medium original sets. And, for a test set that included untrained version variants, we show that classification using coarse template sets nearly matches that of the fine template sets. In a related experiment, we stored 9 initial template sets to classify 9 of the target types and used a threshold to separate the 10(th) type, previously found to be a "confusing" type. We used imagery of all 10 targets in the LVQ training process to modify the 9 template sets. Overall classification performance increased slightly and an equalization of the individual target classification rates occurred, as compared to the 10-template experiment. The SAR imagery that we used is publicly available from the Moving and Stationary Target Acquisition and Recognition (MSTAR) program, sponsored by the Defense Advanced Research Projects Agency (DARPA).