Terrain topography measurement using multipass polarimetric synthetic aperture radar data

Abstract

Abstract. A method has been investigated for the measurement of topography using airborne fully polarimetric synthetic aperture radar (SAR) data. Terrain slopes in both the range and azimuthal directions have been estimated using multipass flight geometries. Using these slope values, the Poisson equation was then solved to create a Digital Elevation Model (DEM) of the terrain topography. The method measures polarimetric orientation angles which are then converted into terrain slopes in the azimuthal direction. The conversion of these orientation angles into terrain slopes requires additional knowledge of the radar look angle and the range direction terrain slopes. The solution for slopes is, therefore, a problem coupled between the range and azimuthal directions. For specialized multipass flight geometries these orthogonal terrain slopes are solved for, and maps of terrain slopes are produced. In particular, the processing of two-pass orthogonal and two-pass antiparallel (headings © and ©+ 180 ø) NASA -Jet Propulsion Laboratory airborne SAR data sets has been carried out for an area in central California. When orthogonal slopes are derived using either of these data sets, a digital elevation model may be generated. The L band, polarimetric SAR (POLSAR) DEM created by this solution is compared to a coregistered C band, interferometric SAR (IFSAR) DEM. Similar comparisons are made for terrain slopes in the azimuthal -range directions which are generated by the POLSAR and IFSAR elevation data. The polarimetric SAR, operating from an aircraft, or satellite, in a strip-mapping mode, is capable of measuring terrain topography for large areas provided that phase-preserving fully polarimetric data are taken. Polarimetric SAR data are also widely used for studies of crop classification, surface roughness, biomass density, and soil moisture content. All of these studies are adversely affected by scattering changes attributable to topography. The technique investigated here potentially offers a means to correct for these effects by making simultaneous, coregistered estimates of local orthogonal terrain slopes.

Polarimetric Scattering Modeling and Information Retrieval of Sar Remote Sensing --- A Review of Fdu Work

“…Since both the range and azimuth angles are coupled, two-or multi-pass SAR image data are required for solving two unknowns of the surface slopes. This approach has been well demonstrated for inversion of digital elevation mapping (DEM) and terrain topography by using airborne SAR data [75,76].…”

A Review of Polarization Orientation Angle Estimation From Polarimetric Sar Data

“…The derived orientation angles can be used to generate topography (Schuler et al [1,2]). Two orthogonal POLSAR flight passes are required to derive orientation angles in perpendicular directions.…”

“…Radar interferometry requires the use of dual antennas separated by a baseline in a single pass system, or by a repeated pass configuration. Recently, a new technique has been developed using polarimetric SAR (POLSAR) to measure azimuth slopes that are related to shifts in polarization orientation angles [1][2][3][4]. Polarization orientation angle is one of the least used parameters among the wealth of polarimetric information when analyzing POLSAR data.…”

A New Method for DEM Generation using a Single POLSAR Flight Pass

“…Among three-dimension imaging techniques using SAR data, a more recent method using POLSAR data has been developed [1,2], which extract terrain slopes in the azimuth or along track direction and elevations. The coupled nature of the polarimetric SAR slope measurement method is revealed in an equation as follows, derived independently by Lee et al [3] and by Pottier [4]: …”