Uni®ed Framework for Modern Synthetic Aperture Imaging Algorithms

ABSTRACT: Imaging using synthetic aperture techniques is a mature under the guise of Project Wolverine to develop a high-resolution technique with a host of different reconstruction algorithms available. combat-surveillance radar system [4]. The ability of SAR to Often the same basic algorithm has a different name depending on remotely observe a scene through cloud cover during day and where the particular algorithm is used, since it may have originated night and through light rain made it ideal for use as a tactical from the medical, nondestructive testing, geological, or remote sens-weapon. The development of the early work in synthetic apertureing ®elds. All this adds to confusion for the nonspecialist. This article radar (or SAR, at it is more usually known) is retraced by Sher-gives a short historical precise of active synthetic aperture imaging win et al. in [1]; a review of his personal involvement is madeas it applies to airborne, spaceborne, and underwater remote sensing by Wiley in [2]. Curlander and McDonough [3] also retracedsystems using either radar or sonar, then de®nes some generic im-developments from an insider’s point of view.aging geometry and places all the usable synthetic aperture recon-struction algorithms in a uni®ed framework. This is done by the intro- Early workers considered unfocused SAR [5]; however, at duction of mapping operators, which simplify the mapping or re- the 1953 meeting, Sherwin indicated that a fully focused synthetic formatting of data from one sampling grid to another. Using these aperture (SA) would produce finer resolution [6, p. 339]. In operators, readers can see how strip-map synthetic aperture systems 1961, Cutrona et al. first published the fact that a fully focuse