SAR2 Technical papers presented at the Automatic Target Recognition Session at the S.P.I.E. Aerosense Conference, Orlando, Florida, April 1998
1. Wallace, Affens, McCandless, "Search and Rescue from Space."
ABSTRACT: NASA Search and Rescue Mission got its start in a highly successful space effort. Now new techniques are emerging which may make it possible to search for downed aircraft from space. This paper discusses the spaceborne search and rescue potential of recent advances in techniques for interferometric SAR, coherent change detection, real time processing and polarimetric ATR.
2. Rogers, Mansfield, Poehler, Rais, "The Wavenumber Shift in Search And Rescue Synthetic Aperture Radar."
ABSTRACT: The wavenumber shift is an important tool in multiple pass synthetic aperture radar interferometry. In addition to overcoming baseline decorrelation, it has proven to have multiple benefits. Chief among these is the ability to filter out much of the decorrelated signal, leaving the coherent portion. In the presence of volumetric scatterers such as foliage, this corresponds to filtering out the return from the foliage and focusing on the ground. We will examine this and other benefits of the wavenumber shift within the context of the Search and Rescue SAR program. Examples based on ERS 1/2 data will be provided.
3. Jackson, Rais, Mansfield, "Polarimetric Target Detection Techniques and Results from the Goddard Space Flight Center Search and Rescue Synthetic Aperture Radar (SAR2) Program."
ABSTRACT: Over the seven years of the Search and Rescue Mission's history, a great deal of original research has been done in the area of automatic target detection for beaconless search and rescue using SAR data. An automated ATR tool has been developed using some of these advanced methods, and has been applied to the test data collected over the years in order to assess the effectiveness of the algorithms in locating downed aircraft. Results are presented.
4. Rais, Mansfield, "L-Band/P-Band SAR Comparison for Search and Rescue."
ABSTRACT: A key question in SAR-aided search is the relative utility of L-band versus P-band data. A study has been completed using target data collected by the NASA Search and Rescue Mission. Comparisons were based on the ability to detect aircraft by use of the many, mostly polarimetry based, automatic detection techniques, developed by the NASA Search and Rescue Mission. The results of this study are presented in this paper.
5. Mansfield, Rogers, Rais, "Real-Time SAR Processing for Search and Rescue."
ABSTRACT: A real-time SAR processor for Search and Rescue Application has been implemented in software, using recent developments in coherent sub-aperture processing algorithms. Benchmark tests have been run and the results have been projected to obtain estimated performance parameters for present and future on-board hardware configurations.
6. Huxtable, Jackson, Skaron, "SAR Processing Using SHARC Signal Processing Systems."
ABSTRACT: The Super Harvard Architecture Computer (SHARC) digital signal processor (DSP) represents the current state of the art in high speed DSPs. Its configuration is uniquely suited to perform the Fast Fourier Transforms required in Synthetic Aperture Radar image formation. This paper presents the results of processing AIRSAR data collected under the Search & Rescue program on a proprietary 6 node SHARC DSP system. The demonstration provides a stepping stone to a real time onboard or high throughput ground station necessary for a fielded Search & Rescue SAR system.
7. Subramanian, Gat, "Subpixel Object Detection using Hyperspectral Imaging for Search and Rescue Operations."
ABSTRACT: Time critical search and rescue (SAR) operations often require the detection of small objects in a vast area. While an airborne search can cover the area, no operational instrumental tools currently exist to actually replace the human operator. By producing the spectral signature of each pixel in a spatial image, multi- and hyper-spectral imaging (HSI) sensors provide a powerful capability for automated detection of subpixel size objects that are otherwise unresolved objects in conventional imagery. This property of HSI naturally lends itself to SAR operations. A lost hiker, skier, life raft adrift in the ocean, downed pilot or small aircraft wreckage targets, can be detected from relatively high altitudes based on their unique spectral signatures. Moreover, the spectral information obtained allows the search craft to operate at substantially reduced spatial resolution thereby increasing scene coverage without significant loss in detection sensitivity. This paper demonstrates the detection of objects as small as 1/10 of an image pixel from a sensor flying at over 6 km altitude. A subpixel object detection algorithm using HSI, based on local image statistics without reliance on spectral libraries is presented. The technique is amenable to fast signal processing and the requisite hardware can be built using inexpensive off the shelf technology. This makes HSI a highly attractive tool for real-time, autonomous instrument-based implementation. It can complement current visual-based SAR operations or emerging synthetic aperture radar sensors that are much more expensive.
8. Yagen, Jackson, Huxtable, "Hunt for Forgotten Warplanes: A Unique Application for Goddard Space Flight Center Search And Rescue Synthetic Aperture Radar (SAR2) Program."
ABSTRACT: An additional and unique application of the SAR2 program at Goddard Space Flight Center is the locating of lost World War II vintage aircraft. Hundreds of such planes crashed in the early 1940's, while flown by new pilots being rushed through flight training. Today, many of these aircraft still lie undisturbed and forgotten in remote sections of the country. They represent one of the best sources of components or rebuildable airframes for restoration purposes. Tidewater Tech operates a chain of vocational trade schools along the Middle Atlantic States. The staff members, along with some of the students, operate a full time restoration shop for rebuilding such vintage planes back to fully flyable conditions. The school has a dedicated team that searches for crash sites. By utilizing sophisticated detection equipment and historical research, numerous locations of military crashes dating back to the war or before have been located. This paper presents some background on the search for historic aircraft. It explains the current methods being used to locate such crash sites and how these actual wreckages can contribute to the continued development of automated target detection in the Search and Rescue processing system.
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