Efficient geolocation and image simulation for extended SAR strip maps

We introduce a more efficient method for implementing backward geocoding. For grid locations sparsely spaced along the extended swath, forward geocoding is used to calculate map coordinates corresponding to near and far-range locations (at a single nominal height). A buffer extends the near and far range positions to account for differences between nominal and true (DEM) heights. All map co-ordinate locations outside these boundaries are marked a priori as "no data" positions (no radar data available there). Within the confines of these boundaries, geolocation proceeds normally. We document the run-time improvement provided, and show how the increase in efficiency provided by geolocation confinement grows quadratically with the length of the swath. We demonstrate significantly improved run times for image simulation using simulated ENVISAT products generated with ERS data