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 goal of this study is to evaluate some polarimetric speckle filters when applied to Compact Polarimetry (CP) data. Seven filters are evaluated on a set of artificial CP images. Performances regarding image restoration and polarimetric information preservation are evaluated.

An evaluation of PolSAR speckle filters on Compact-Pol images

Cameron's coherent target decomposition (CTD) theory and the classification method that Cameron developed for operational use of his CTD are reconsidered in this paper. It is shown that Cameron's classification leads to a coarse scattering segmentation because of the large class dispersion that corre- sponds to a synthetic aperture radar (SAR) system with about 8-dB channel imbalance. The application of Cameron's method within known SAR radiometric calibration requirements limits the utility of the classification. In addition, Cameron's classifica- tion is applied under the implicit assumption on the coherence nature of target scattering, and this might yield erroneous results within areas of noncoherent scattering. A new method, named the symmetric scattering characterization method (SSCM), is introduced to better exploit the information provided by the largest target symmetric scattering component in the context of coherent scattering. The Poincare sphere is used as the basis for a more complete representation of symmetric scattering than Cameron's unit disk, thus enabling the SSCM to generate better segmentation of target symmetric scattering with much higher resolution. In order to limit the application of the SSCM to targets of coherent scattering, new methods are developed for assessment and validation of the coherent nature of point and extended target scattering. Index Terms—Cameron's classification, coherency matrix, co- herent scattering, Mueller matrix, polarimetric, scattering matrix, symmetric scattering, synthetic aperture radar (SAR), target de- composition theory.

Characterization of Target Symmetric Scattering

We are proposing recursive filter for the filtering of Single Look Complex PolInSAR data. This recursive filter allows the iterative refinement of a coarse multilook estimate by reintroducing details that have been oversmoothed. We investigate if wether or not information about the image structure (i.e. spatial details) could be recovered from all the terms of the PolInSAR matrix. Preliminary results on simulated images show also that bias on various polarimetric parameters are decreasing with iterations.

The polarimetric ratio filter applied to polinsar images

This chapter provides a summary of the most current sensors being used for monitoring infrastructure. We also provide case studies on:


The use of time-series radar interferometry (InSAR) to monitor critical highways, railways, and pipelines affected by landslides that are triggered by coastal erosion, spring snowmelt, permafrost thaw, monsoons, and hurricanes.


The use of InSAR, change detection, and image fusion techniques to explore and monitor mining sites.


The use of radar images to monitor shoreline change and oil spills.

Advanced Radar Images for Monitoring Transportation, Energy, Mining and Coastal Infrastructure

The Canadian RADARSAT Constellation Mission (RCM, to be launched in 2018) will consist of three C-band Synthetic Aperture Radar satellites. The equivalent four day repeat cycle of RCM will allow monitoring fast ground uplift and subsidence in Alberta's oil sands region, where the Steam Assisted Gravity Drainage (SAGD) and the Cyclical Steam Simulation (CSS) enhanced oil recovery technologies are employed. Previous observations showed slow and steady uplift at the SAGD sites and very fast uplift and subsidence at the CSS sites. The forthcoming RCM and currently operated RADARSAT-2 satellites display significant differences in resolution, coverage, and noise floor. Using RCM simulator we evaluated average interferometric coherence vs spatial resolution and noise floor. We determined that noise floor moderately affects coherence but main limitation is imposed by resolution. The Very High and High resolution RCM beams are best for monitoring ground deformation in Alberta's oil sands.

François Charbonneau

Papers

An evaluation of PolSAR speckle filters on Compact-Pol images

Characterization of Target Symmetric Scattering

The polarimetric ratio filter applied to polinsar images

Advanced Radar Images for Monitoring Transportation, Energy, Mining and Coastal Infrastructure

RADARSAT constellation mission for monitoring ground deformation in Alberta's oil sands