SAR2 Technical papers presented at the Automatic Target Recognition Session at the S.P.I.E. Aerosense Conference, Orlando, Florida, April 2000
1. Dreibelbis, Hembree, Affens, "Prototype Airborne Search and Rescue System."
ABSTRACT: Crashed aircraft often slice through the trees without leaving a detectable entry point or other indication of their presence. In addition there are many times and for many reasons that no emergency beacon operates in such a crash. For these cases, NASA has been experimenting with airborne synthetic aperture radar to provide a search tool to help focus the visual searches that are initiated following these crashes. This paper reviews a proposed operational scenario and the elements of a prototype airborne system that could be brought into use for finding crashed aircraft obscured from visual view.
2. Rais, Mansfield, Chotoo, "The Virginia Beach Search and Rescue Experiment."
ABSTRACT: In May, 1998, the NASA Search and Rescue Mission conducted a SAR crash detection test in the swampy area south and west of Virginia Beach. A number of aircraft parts are hidden in the dense foliage. The radar used was the Navy P-3 with the ERIM XLC SAR, providing fine resolution imagery with full polarimetry and an IFSAR capability. This paper reports the results of this test.
3. Chotoo, Huxtable, "Probability of Detection of Downed Aircraft using SAR polarimetry."
ABSTRACT: In developing a beaconless search and rescue capability to quickly locate small aircraft that have crashed in remote areas, NASA's Search and Rescue Program brings together advanced polarimetric synthetic aperture radar processing, field and laboratory tests and crash site detection algorithms. The fundamental idea underlying the search and rescue (S&R) approach is use of an airborne polarimetric radar. The downed aircraft is partly composed of metal, and consists of regular geometric shapes such as flat plates, dihedrals, trihedrals, etc., which produce a polarization signature expected to be distinct from that of surrounding terrain and foliage. Onboard polarimetric SAR image formation combined with automatic image exploitation will ultimately cue the S&R team to candidate crash sites in near real-time. We empirically examine the probability of detection (PD) and false alarm rate (FAR) for crash site detection using polarimetry to discriminate between aircraft target signatures within natural clutter. This briefing will present the latest results from the S&R Program activities, providing an update to the last program presentation to the SPIE Meeting in 1999.
4. Breitenstein, Rogers, Roth, Huxtable, "Advanced Resolution Enhancement Techniques for Search and Rescue."
ABSTRACT: There are a number of methods well documented in the literature for increasing the resolution of an image product beyond the resolution limit of the EO or radar sensor that acquired the data. This paper reports on an investigation of these techniques for "super-resolution" and their applicability to Search and Rescue Synthetic Aperture Radar (SAR2).
5. Rogers, Mansfield, Rais, "The Interferometric SAR to EO Image Registration Problem."
ABSTRACT: Historically, SAR to EO registration accuracy has been at the multiple pixel level compared to sub-pixel EO-to-EO registration accuracies. This is due to a variety of factors including the scattering characteristics of the ground for EO and SAR, SAR speckle, and terrain induced geometric distortion. One approach to improving the SAR to EO registration accuracy is to utilize the full information from multiple SAR surveys using interferometric techniques. In this paper we will examine this problem in detail with an example using ERS SAR imagery. How this improved registration accuracy can impact the crash site detection problem as well as the target geolocation problem will also be discussed.
6. Rogers, Breitenstein, Mansfield, Rais, "Full Resolution Interferometric SAR Processing."
ABSTRACT: In this paper we present our approach to full resolution IFSAR processing that retains full azimuth and range resolution for a significant fraction of the pixels. This is accomplished through the use of statistical analysis and nonlinear smoothing. In our approach, a significant fraction of the pixels retain their original phase values all of the way through map generation. At the same time, we are able to reduce the number of residues by several orders of magnitude. An additional benefit of this approach is the ability to detect and discriminate between complete decorrelation due to large bodies of water and partial decorrelation due to foliage. The approach will be presented along with examples based on ERS tandem pair data.
7. Schwartz, Mansfield, Roth, Rais, "P-3 SAR Motion Compensation Techniques."
ABSTRACT: SAR interferometry (IFSAR) was used in the processing of P-3 airborne SAR data for an evaluation of the potential of airborne SAR to provide separate-pass interferometric products like Coherent Change Detection
(CCD) and Digital Elevation Matrices (DEM) to support a search and rescue mission. The most crucial step in this process is the precise registration of the two SAR images. This paper presents a new technique for this registration step.
8. Mansfield, Poehler, Huxtable, Rais, "Complex Data Compression Techniques: Some New
Approaches."
ABSTRACT: The most important parameter in Search and Rescue is the time it takes to locate the downed aircraft and rescue the survivors. The resulting requirement for wide-area coverage, fine resolution, and day-night all-weather operation dictates the use of a synthetic aperture radar (SAR) sensor. The time urgency combined with the high data volume leads to the need for a new type of data compression. This paper presents and evaluates candidate compression algorithms for SAR raw phase history and for SAR complex imagery.
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