PRACTICAL AND THEORETICAL IMPLICATIONS OF X-BAND AND L-BAND DUAL-POLARIZED RADAR IMAGES OF METROPOLITAN LOS ANGELES (CALIFORNIA).

摘要

During the 1980's, both the National Aeronautics and Space Administration (NASA) and the European Space Agency plan to repeatedly launch imaging radar systems on the Space Shuttle. As a result, there is pressing need for ongoing studies of radar interaction mechanisms and the resulting image signatures.; This research was based on four radar mosaics of metropolitan Los Angeles, CA, acquired in 1979 and made available by NASA's Jet Propulsion Laboratory. Both the X-Band and L-Band mosaic pairs (1) were aircraft synthetic aperture radar (SAR) data, (2) have a horizontal transmission polarization, (3) have both horizontal and vertical recorded polarizations, and (4) have a nominal due-North look direction. Three field sites were selected for intensive study. The primary research objectives were to (1) broaden and improve the theory of L-Band cross-polarizing interaction mechanisms and (2) determine optimum digital and photographic processes for simultaneous analysis of multiple images.; Nine case studies of bright L-HV signatures demonstrate that chain link fences are efficient L-Band depolarizing reflectors that can be used as a tool to investigate L-Band vegetation penetration capability in an urban environment. It was found that the vegetation penetration capability of this L-Band system at these field sites is minimal.; For each field site, Level III land use/cover maps were prepared that, together with six case studies of anomalous bright X-Band and L-Band signatures, demonstrate that diffraction can be an efficient depolarizing mechanism for both X-Band and L-Band wavelengths. Also, because of the strong electromagnetic interactivity of trihedral corner reflectors with metal walls, imaging radar systems can discriminate conducting from dielectric materials in non-cardinally oriented urban areas.; For the Glendale field site, digital contrast stretch and ratio images were prepared and then analysed singly and in combination to determine an efficient means of extracting information from multi-band, multi-polarization SAR image sets. Monochromatic ratio images were a very useful means of comparing two images simultaneously. Tri-color composites of both raw and ratio images also proved very useful, with optimum results obtained when printing the best image in green, the second-best red, and the third-best in blue.