A synthetic aperture radar (SAR) often is constrained to transmit only one polarization. Within this constraint, two aggressive measurement objectives are 1) full characterization and exploitation of the backscattered field, and 2) invariance to geometrical orientations of features in the scene. Full characterization implies coherent dual-polarization to support the four Stokes parameters. These are rotationally invariant with respect backscatterer orientation if and only if the transmission is circularly polarized. Given that the data products are the Stokes parameters, the receivers can use any orthogonal polarization basis. A SAR in hybrid-polarity architecture (CL-pol) transmits circular polarization and receives two orthogonal mutually coherent linear polarizations, which is one manifestation of compact polarimetry. The resulting radar is relatively simple to implement, and has unique self-calibration features and low susceptibility to noise and cross-channel errors. It is the architecture of choice for two lunar radars scheduled for launch in 2008. Data from a CL-pol SAR yield to decomposition strategies such as the m-delta method introduced in this paper.

https://earth.esa.int/workshops/polinsar2009/participants/141/paper_141_s7_1rane.pdf

Hybrid-Polarity SAR Architecture

: This report is a review of the publicly available literature on algorithms for detecting ships in Synthetic Aperture Radar (SAR) imagery, with the aim of recommending algorithms for inclusion in the Analysts' Detection Support System (ADSS). The ADSS is a software system being developed at DSTO for the automatic detection of targets in SAR imagery. We outline the motivations, theory and justifications of the various approaches so that educated comparisons and evaluations can be made. Most current research on ship detection is based on detecting the ship itself rather than its wake. Detection of ship wakes is not addressed in any depth. Ship detection systems generally consist of several stages: land masking; preprocessing; prescreening; and discrimination. We consider each of these stages in turn and discuss the various algorithms which have been used. A basic system for low to medium resolution single channel SAR imagery is recommended and suggestions for improvements and alternatives are made.

/pdf/the-state-of-the-art-in-ship-detection-in-synthetic-aperture-40c27vh09z.pdf

The State-of-the-Art in Ship Detection in Synthetic Aperture Radar Imagery

Spaceborne differential synthetic aperture radar interferometry (DInSAR) has already proven its potential for mapping ground deformation phenomena, e.g. volcano dynamics. However, atmospheric disturbances as well as phase decorrelation have prevented hitherto this technique from achieving full operational capability. These drawbacks are overcome by carrying out measurements on a subset of image pixels corresponding to pointwise stable reflectors (Permanent Scatterers, PS) and exploiting long temporal series of interferometric data. Results obtained by processing 55 images acquired by the European Space Agency (ESA) ERS SAR sensors over Southern California show that the PS approach pushes measurement accuracy very close to its theoretical limit (about 1 mm), allowing the description of millimetric deformation phenomena occurring in a complex fault system. A comparison with corresponding displacement time series relative to permanent GPS stations of the Southern California Integrated GPS network (SCIGN) is carried out. Moreover, the pixel-by-pixel character of the PS analysis allows the exploitation of individual phase stable radar targets in low-coherence areas. This makes spaceborne interferometric measurements possible in vegetated areas, as long as a sufficient spatial density of individual isolated man-made structures or exposed rocks is available. The evolution of the Ancona landslide (central Italy) was analysed by processing 61 ERS images acquired in the time span between June 1992 and December 2000. The results have been compared with deformation values detected during optical levelling campaigns ordered by the Municipality of Ancona. The characteristics of PS, GPS and optical levelling surveying are to some extent complementary: a synergistic use of the three techniques could strongly enhance quality and reliability of ground deformation monitoring. D 2002 Elsevier Science B.V. All rights reserved.

Monitoring Landslides and Tectonic Motions with the Permanent Scatterers Technique

The Kennaugh-Huynen scattering matrix con-diagonalization is projected into the Pauli basis to derive a new scattering vector model for the representation of coherent target scattering. This model permits a polarization basis invariant representation of coherent target scattering in terms of five independent target parameters, the magnitude and phase of the symmetric scattering type introduced in this paper, and the maximum polarization parameters (orientation, helicity, and maximum return). The new scattering vector model served for the assessment of the Cloude-Pottier incoherent target decomposition. Whereas the Cloude-Pottier scattering type alpha and entropy H are roll invariant, beta and the so-called target-phase parameters do depend on the target orientation angle for asymmetric scattering. The scattering vector model is then used as the basis for the development of new coherent and incoherent target decompositions in terms of unique and roll-invariant target parameters. It is shown that both the phase and magnitude of the symmetric scattering type should be used for an unambiguous description of symmetric target scattering. Target helicity is required for the assessment of the symmetry-asymmetry nature of target scattering. The symmetric scattering type phase is shown to be very promising for wetland classification in particular, using polarimetric Convair-580 synthetic aperture radar data collected over the Ramsar Mer Bleue wetland site to the east of Ottawa, Ontario, Canada

https://www.pcigeomatics.com/pdf/whitepapers/Touzi_target_scattering.pdf

Target Scattering Decomposition in Terms of Roll-Invariant Target Parameters

This article presents an automated Sentinel-1-based processing chain designed for flood detection and monitoring in near-real-time NRT. Since no user intervention is required at any stage of the flood mapping procedure, the processing chain allows deriving time-critical disaster information in less than 45 min after a new data set is available on the Sentinel Data Hub of the European Space Agency ESA. Due to the systematic acquisition strategy and high repetition rate of Sentinel-1, the processing chain can be set up as a web-based service that regularly informs users about the current flood conditions in a given area of interest. The thematic accuracy of the thematic processor has been assessed for two test sites of a flood situation at the border between Greece and Turkey with encouraging overall accuracies between 94.0% and 96.1% and Cohen’s kappa coefficients κ ranging from 0.879 to 0.910. The accuracy assessment, which was performed separately for the standard polarizations VV/VH of the interferometric wide swath IW mode of Sentinel-1, further indicates that under calm wind conditions, slightly higher thematic accuracies can be achieved by using VV instead of VH polarization data.

Sentinel-1-based flood mapping: a fully automated processing chain

The Thompson River valley, south of Ashcroft in British Columbia, Canada, has experienced several landslides since the mid-1800s. The national railways that run along the valley cross a number of these landslides. All the landslides occur in glacial deposits, typically sliding on weak clay layers. Some have failed rapidly to very rapidly and are currently inactive or showing deformation rates from a few millimeters to centimeters per year. An evaluation of satellite InSAR (Interferometric Synthetic Aperture Radar) using RADARSAT-2 images between September 2013 and November 2015 provides new insight into landslide displacements in the Thompson River valley. This information enhances the ongoing hazard management of unstable terrain. This paper presents the comparison of the InSAR measurements with other instrumentation (GPS and ShapeAccelArrays™ -SAA) installed at one moving landslide and then addresses the extent and magnitude of the slope movements observed. InSAR was found to provide similar displacement values to those measured otherwise. The stable location showed displacements of +/−1 mm with an average near zero during the whole monitoring period. Six areas of slope movement were identified within the study area, all within or adjacent to the footprints of past landslides. The average line of sight (LOS) displacement rates range between 11 and 39 mm/year. Most of the landslides exhibited seasonal variations in velocity that corresponds to changes in river elevation in the valley.

Measuring displacements of the Thompson River valley landslides, south of Ashcroft, BC, Canada, using satellite InSAR

. Compact polarimetric synthetic aperture radar (SAR) architecture is an SAR configuration that consists of transmitting a single circular polarization (left or right) or a 45° oriented linear signal while receiving two linear polarizations, horizontal and vertical. In this study we investigate the potential of the compact polarimetric SAR mode for wetland monitoring applications. Whitewater Lake located in Manitoba, Canada, is selected as a case study where simulated compact polarimetric SAR data are obtained using RADARSAT-2 Fine Quad-POL SAR images. The ability of the compact polarimetric data to monitor wetlands using the Wishart-Chernoff distance is studied and compared to the results obtained using fully polarimetric data. Results of this study show that compact polarimetry provides monitoring capabilities for wetlands. Promising change detection mapping results based on the compact polarimetric coherency matrices are obtained using the Wishart-Chernoff distance. This could be useful for fla...

Change Detection with Compact Polarimetric SAR for Monitoring Wetlands

The state of the art in compact SAR calibration is reconsidered. It is shown that all the existing Compact calibration methods are built on the assumption that the Compact transmits a perfect circular polarization (CP). Unfortunately, the actual technology does not permit the generation of a perfect CP wave. The impact of non circularity of the transmitted polarization on Compact polarization information is assessed. The variations with incidence angles of the helicity and ellipticity of the transmitted polarization are simulated for C-band and L-band Compact SAR using Radarsat-2 and Alos data. This permits quantification of the resulting radiometric error on RH and RV dual-pol measurements. The impact of the non circularity of the transmitted polarization on the degree of polarization (DoP) and Compact polarization synthesis is also quantified. The requirements on the calibration of compact SAR for the extraction of a meaningful polarimetric SAR information from compact, are then setup.

Requirements on the calibration of Hybrid-Compact SAR

QuiP is a graphical user interface (GUI) developed in MATLAB to extract and analyze soil surface profile measurements obtained from a needle profiler in a few minutes. Surface roughness parameters can be extracted from any needle profiler with simple modifications to the tool. QuiP calculates many statistics useful in radar remote sensing while generating the profiles. Furthermore, a QuiP function can be used to join several profiles. Long profiles can therefore be created from a short profiler (e.g., 1 m) that is easier to carry and handle in the field. Extraction of profiles by QuiP is repeatable and therefore reduces user’s errors from data processing.

Quick Profiler (QuiP): a friendly tool to extract roughness statistical parameters using a needle profiler

. The incidence angle, wind speed, and wind direction dependence of compact polarimetry (CP) synthetic aperture radar (SAR) parameters are presented for open water. Selected CP parameters are related to C-band geophysical model function (CMOD) output. Wind speeds range between 0 and 24 m/s, and incidence angles range between 18 and 50°. SAR data are coincident with meteorological buoy data. CP parameters are simulated from polarimetric RADARSAT-2 data and emulate data available on the pending RADARSAT Constellation Mission (RCM). Analysis is performed for 20 CP parameters, based on RADARSAT-2 images. Five linear-polarization SAR parameters are included for comparison. Results show robust relationships for CP parameters related to CMOD. For CP parameters unrelated to CMOD, results provide first-, second-, or third-order linear regression models, as functions of incidence angle, wind speed, wind direction, or combinations thereof. These models provide a set of values for comparison with sea ice or o...

François Charbonneau

Papers

Measuring displacements of the Thompson River valley landslides, south of Ashcroft, BC, Canada, using satellite InSAR

Change Detection with Compact Polarimetric SAR for Monitoring Wetlands

Requirements on the calibration of Hybrid-Compact SAR

Quick Profiler (QuiP): a friendly tool to extract roughness statistical parameters using a needle profiler

Ocean Wind Study Using Simulated RCM Compact-Polarimetry SAR