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Synthetic Aperture Radar (EUSAR), 2008 7th European Conference on

Date 2-5 June 2008

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Displaying Results 1 - 25 of 302
  • Advanced Onboard Technologies for ISRO¿s RISAT-I Follow-on L-Band Polarimetric SAR Mission

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (150 KB)  

    Since 1985, ISRO/India has been working on Synthetic Aperture Radar (SAR) technologies under its Microwave Remote Sensing Programme (MRSP). During these years, ISRO has already developed and operationalised two airborne C-band imaging SAR systems. Thereafter, RISAT-1 multi-mode spaceborne SAR development has been initiated. Various onboard base-band subsystems and Tile Electronics of RISAT-1, scheduled for launch in 2008/2009 timeframe are in advanced stages of development. For the next decade, ISRO has also planned a number of future SAR missions in LEO orbits like L-band Polarimetric SAR, P- and X-Band Agile Airborne and Small Satellite SARs. The major subsystems of all these future microwave missions will also be based on Core Radar electronics developed for RISAT-1. Considering the obvious advantages offered by L-band microwave remote sensing for Agriculture applications and India being predominantly agriculture based economy, ISRO has identified L-band Polarimetric SAR mission as the main follow-on mission of RISAT-1. The basic design requirements for this L-band SAR mission are 30- 240 km swath coverage with moderate 5-25 meter resolution, Stripmap and ScanSAR operating modes with polarimetric capability. The design and development of various advanced technology elements like active antenna consisting of about 80 miniaturized Transmit/Receive modules with associated controls and onboard base-band Digital Subsystems like Data Acquisition and Compression system (DACS), Digital Chirp Generator (DCG), Distributed Embedded Controller consisting of Payload Controller (PLC), Tile Control Units (TCU) and TR Control (TRC) units, have been initiated. This apart, RISAT-1 Ground segment consisting of Real / Near Real Time Quick Look SAR Processor (QLP) and Ground Checkout Units (GCU) will also be augmented and utilized for this L-band SAR mission. This paper gives the details of design requirements of L-band Polarimetric SAR, tradeoffs, salient features, implementation de- - tails and preliminary test results of the various advanced onboard technology elements for L-band multi-mode Polarimetric SAR payload for ISROï¿¿ï¿¿ï¿¿s RISAT-1 follow-on satellite mission. View full abstract»

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  • On Space-based Synthetic Aperture Radar Antennas

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (154 KB)  

    Several Space-borne Synthetic Aperture Radar (SAR) instruments have been realised. Different antenna design solutions have been selected. It is noted, that in 2007 (nearly 30 years after Seasat) four different antenna designs have been implemented. Antennas based on a reflector (SAR-Lupe) or based on active phased array are used, the latter with waveguide- (TerraSAR-X) or patch-radiators (Radarsat 2, Cosmo-Skymed). Further developments and investigations continue, also with exploitation of digital beam-forming not only for (phased) array antenna-based solutions but also possibly for implementations with feed arrays within reflector antennas. View full abstract»

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  • One-Bit Digitization for DBF-SAR: Too Good to be True

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (80 KB)  

    How many bits of resolution can be chosen as a minimum for the quasi-lossless digitization of radar signals with low signalto- noise power ratio (SNR)? The answer to this question is important for the design of the receive electronics of future Digital Beam-Forming SAR instruments (DBF-SAR) due to their concept of multi-channel digitization. Clearly, fewer bits should be required for the digitization of a radar signal with low SNR than with high SNR because more digitization noise is acceptable in the former case. One-bit digitization would be particularly desirable from an implementation point of view. The assumptions commonly made when modelling the digitization noise are true for the many-bit case but do not hold for few-bit modelling, so a special metric is needed in this case to correctly determine SNR after digitization. This metric and simulations based on it are presented. They show that one-bit digitization always results in a loss of SNR of at least 2 dB, no matter how low the input SNR is, and that in fact as a minimum 3 bits should be used. This minimum number of bits is subject to further increase depending on the dynamic range of the signal. An engineering formula is presented which allows to quickly estimate the optimum bit number for an N-channel receive antenna and a specified dynamic range of the pseudo-Gaussian radar signal. View full abstract»

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  • A pod with a very long broadband time steered array antenna for PAMIR

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1173 KB)  

    A reconfigurable pod-mounted antenna frontend configuration for the PAMIR SAR/GMTI imaging radar, an experimental active phased array system with a very high instantaneous bandwidth of 1.82 GHz in X-band is described. The pod accommodates a linear time and phase steered array antenna with a length of 4.25 m. Broadband beamforming together with wide azimuth scan capabilities (=± 45deg@1.82 GHz bandwidth) requires a switchable true time delay network with time increments equivalent to a fraction of a wavelength. The subarray structure including the time delay components and the total array performance are described. PAMIR serves as an ideal airborne platform for future broadband SAR/GMTI research activities including interferometric image formation. View full abstract»

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  • TerraSAR-X high resolution SAR data: Ground motion and mapping applications for infrastructure, oil & gas and public health domain

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (574 KB)  

    The successful launch of TerraSAR-X has made available high resolution SAR images with new image characteristics. The objective of this paper is to present the experience of ALTAMIRA INFORMATION regarding the impact of these new data in commercial applications. Case studies will illustrate the findings. View full abstract»

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  • Hybrid-Quadrature-Polarity SAR Architecture

    Publication Year: 2008 , Page(s): 1 - 2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (123 KB)  

    Data products from a quadrature-polarized synthetic aperture radar (SAR) are fully characterized by Stokes parameters. In follows that choice of the polarization basis of both the transmitted and received EM fields has no impact on the measurement potential of the system. Hence the polarization plan can be selected to optimize the radar¿s technical performance. The logical conclusion is that the radar should transmit circular polarization, and receive orthogonal linear polarizations - the hybrid-quadrature-polarity architecture. View full abstract»

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  • Compact Polarimetric Observation using Phased Array Antenna and Its Case Study for PALSAR

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    This paper presents the study of compact polarimetric (CP) mode for SAR using the phased array antenna. CP mode can be realized without a special mechanism, only with two separate parts of the antenna in elevation which transmits different polarization respectively. The reconstruction algorithm processes the change of the phase between H- and V-polarizations. And the case study shows the feasibility, examples of the operation and the possible performance of CP mode using ALOS/PALSAR on orbit. View full abstract»

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  • Requirements for Model-Based Polarimetric Decompositions

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    Several authors have proposed decompositions of measured polarimetric covariance matrices into the weighted sums of individual covariance matrices that represent known scattering models. In this paper we critically examine some minimum requirements that these model-based polarimetric scattering decompositions must satisfy. Starting with the definition of the covariance matrix, we show that a necessary requirement for these decompositions is that the eigenvalues of the individual covariance matrices must be non-negative. We then show with examples that this is not guaranteed for some of the proposed decompositions. Finally, we propose a method of decomposition that would ensure that the eigenvalues of the individual covariance matrices would be non-negative. View full abstract»

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  • Investigation on the Performance of Compact Polarimetry in SAR Interferometry

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (193 KB)  

    In this paper, we investigate the role and the performance of compact polarimetry in SAR interferometry. The considered SAR architecture is assumed to transmit either a circular polarized wave or a linear polarized one oriented at 45 degrees (pi/4), and to receive at horizontal and vertical polarization. Two polarimetric acquisitions are combined in an interferometric image, characterized by a polarimetric and interferometric covariance matrix. The expression of the PolInSAR covariance matrix for compact polarimetry is derived and discussed. The reconstruction algorithm of full polarimetry is developed and applied to PolInSAR simulated data, in order to assess the performance of the compact PolInSAR configuration. The simulated targets are forests, for which PolInSAR algorithms have found important applications. An assessment on the performance of compact polarimetry is carried out based on the comparison between the interferometric degree of coherence versus forest height observed by compact polarimetry and full polarimetry. The comparison shows a general good agreement between the two configurations. View full abstract»

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  • Bistatic SAR Experiment with the Ingara Imaging Radar: Preliminary Results

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (319 KB)  

    The Ingara fully-polarimetric X-band airborne imaging radar system has recently been upgraded to conduct experimental SAR data collections in a bistatic geometry. Initial trials of the new bistatic SAR system were conducted in late 2007: these involved operation of the airborne radar in a fine-resolution (600 MHz bandwidth) circular spotlight-SAR mode, in conjunction with a newly-developed fully-polarimetric stationary ground-based bistatic receiver. This paper gives an overview of the Ingara bistatic SAR system, discusses the experiments and data processing, and presents initial experimental results. View full abstract»

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  • Hybrid Bistatic SAR Experiment TerraPAMIR ¿ Geometric Description and Point Target Simulation

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    Because of the high difference between the platform velocities in a bistatic hybrid experiment involving a spaceborne SAR system as transmitter and an airborne system as receiver, azimuth antenna steering on both systems is necessary. To make both antenna footprints overlap for a sufficient time interval, the double sliding spotlight mode was defined: While the transmitter operates in sliding spotlight mode to slow down the azimuth velocity of the footprint center, the receiver footprint is accelerated in azimuth. This work describes the geometry and some parameter calculations for a simulation including the WGS84 ellipsoid and the earth rotation. It concludes with an analysis on the basis of simulated point targets. View full abstract»

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  • Bistatic Experiment Using TerraSAR-X and DLR¿s new F-SAR System

    Publication Year: 2008 , Page(s): 1 - 4
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1017 KB)  

    A bistatic X-band experiment was successfully performed early November 2007. TerraSAR-X was used as transmitter and DLR¿s new airborne radar system F-SAR, which was programmed to acquire data in a quasicontinuous mode to avoid echo window synchronization issues, was used as bistatic receiver. Precise phase and time referencing between both systems, which is essential for obtaining high resolution SAR images, was derived during the bistatic processing. Hardware setup and performance analyses of the bistatic configuration are presented together with first processing results that verify the predicted synchronization and imaging performance. View full abstract»

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  • A real time simulation model for estimation of position and orientation of two airborne SAR systems platforms inMatlab/Simulink: description,

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    In the last few years, researchers¿ interests have been focused on a new kind of imaging radars: bi-/multistatic SAR (Synthetic Aperture Radar) systems. The reason of this attention has to be sought in the advantages of this kind of systems in several SAR applications such as SAR/GMTI, interferometry and tomography, for instance. On the other hand several problems occur due to the separation of transmitter and receiver. It is important for these systems to know very precisely platforms positions and to synchronize transmitter and receiver time base. This is why a navigation-system is needed which is able to solve these kind of problems. In addition to this, the navigation-system also has to be able to estimate the orientation of receiver platform with respect to transmitter as well, in order to illuminate the same area of interest. This paper describes a method, which is able to estimate the position and orientation of two airborne platforms towards each other with the demanded accuracy and which is able to synchronize the RX-system to the TX-system. The hardware is described and the simulation in Matlab/Simulink performed. First simulation results are presented to confirm the performances of previous investigations. View full abstract»

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  • Oboard Radar Processor of SOSTAR-X

    Publication Year: 2008 , Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (458 KB)  

    The SOSTAR-X system is an advanced airborne ground surveillance radar system. This multi-mode radar demonstrator allows the acquisition of highly squinted and long range data in several SAR, Classification and MTI modes, as well as in simultaneous SAR/MTI modes. Furthermore, tracking functionalities are included. The radar raw data are processed onboard the aircraft on a real-time Radar Processor. The Radar Processor development was shared between the SOSTAR-X companies Dutch Space (NL), EADS (DE), Galileo Avionica (IT), Indra Sistemas (ES) and Thales (FR). Flight trials on a Fokker F100 aircraft were performed in 2006 and 2007. This paper presents the architecture of the SOSTAR-X Radar Processor and some spotlight SAR processing results from the flight trials. View full abstract»

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  • SAR amplitude filtering using TV prior and its application to building delineation

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (209 KB)  

    This paper investigates the use of a popular regularization model, the Total Variation minimization (TV), to filter SAR images and reduce speckle noise. This model is extensively used for its property of preserving edges. Due to the many local minima, TV minimization is difficult to achieve for non-convex likelihood terms such as that of SAR amplitude. Such a minimization can be performed efficiently by computing minimum cuts on weighted graphs. Exact minimization, although theoretically possible, can not be implemented due to memory constraints on large images required by remote sensing applications. The computational burden of the state-of-the-art algorithm for approximate minimization is also heavy. In this paper, we propose a new fast approximate discrete algorithm. The filtering is applied in the framework of building delineation for 3D reconstruction. Results on real images are presented. View full abstract»

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  • Wave Number Domain Processing on Squinted Spotlight SAR Data of the Sostar-X Sensor

    Publication Year: 2008 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (590 KB)  

    The Sostar-X system is a multi mode Radar demonstrator that allows the acquisition of high squinted and long range spotlight SAR data. High squint and long range together with the high resolution of the Sostar-X sensor evoke special efforts for the algorithm of a SARprocessor. This paper discusses these problems and presents some spotlight SAR processing results of Sostar-X data. View full abstract»

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  • Modified Fast Factorized Backprojection as Applied to X-Band Data for Curved Flight Paths

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (929 KB)  

    A Fast Factorized Backprojection scheme modified to X-band frequencies and applicable to small aperture beamwidths is presented to compute SAR images from real and synthetic airborne data sets. The numerical complexity and memory consumption of the algorithm is verified and compared to ordinary Backprojection. The modified Fast Factorized Backprojection scheme is investigated for exceedingly curved flight paths and compared to an omega-k algorithm in combination with a motion error correction. Excellent SAR image focusing results were found for the modified Fast Factorized Backprojection approach while keeping the numerical complexity to O(N2log(N)). View full abstract»

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  • Ship traffic monitoring using multi-polarisation satellite SAR images combined with AIS reports

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (233 KB)  

    Ship traffic monitoring may be carried out more effectively by combining satellite SAR images with an automatic ship identification system (AIS). We show how detecting ships within SAR images can be made more reliable if several polarisations are combined with appropriate radar incidence angles during acquisition. A common knowledge base of SAR ship signatures for particular polarisations and inci-dence angles are built up by combining ships detected in SAR images with ship parameters given in AIS reports from the existing coastal chain in Norway. An operational system should combine satellite AIS reports with satellite SAR images for rescue and security operations. View full abstract»

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  • TerraSAR-X System Performance & Command Generation

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    The paper starts with an overview about the TS-X data take command generation. The general approach of calculating particular instrument settings for each data acquisition is presented. Selected details are presented allowing a better understanding of presented results. The data take planning and commanding especially in the commissioning phase is resumed. The second part concentrates on the SAR system performance, i.e. obtained verification results are presented together with the resulting improvements in the data take commanding. View full abstract»

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  • TerraSAR-X Calibration Results

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (761 KB)  

    TerraSAR-X is a satellite mission for scientific and commercial applications operating a highly flexible X-band SAR instrument with a multitude of different operation modes. As product quality is of crucial importance, the success or failure of the mission depends essentially on the method of calibrating TerraSAR-X in an efficient way during commissioning the entire system in a restricted time. Only then, product quality and the correct operation of the SAR system can be ensured. The paper describes the method of calibrating TerraSAR-X and final results derived from all calibration procedures. View full abstract»

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  • TerraSAR-X SAR Payload Data Processing: Results from Commissioning and Early Operational Phase

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (531 KB)  

    TerraSAR-X, the first national German radar satellite, was launched in June 2007. It carries an X-band highresolution synthetic aperture radar instrument featuring the operational imaging modes Stripmap, ScanSAR and, particularly, Spotlight in a variety of different polarization modes. The TerraSAR-X mission completed its commissioning phase in December 2007 and started the provision of high-resolution products from advanced SAR modes for both the scientific and commercial user community from January 2008 on. The payload ground segment (PGS) is responsible for the reception of the SAR payload data, their archiving and processing and the distribution of the generated SAR basic products to users. From the first mission day on, PGS was operated successfully using both its request workflow starting with the input of user orders and ending with the delivery of the generated product and its operational SAR data workflow for the reception and processing of the SAR payload data. The central part of PGS is the TerraSAR Multi-Mode SAR Processor (TMSP) focusing the SAR data in a unified way for the different imaging configurations. A wide range of processing options spanning from phase preserving complex products in slant range geometry to orthorectified terrain corrected intensity images lead to a comprehensive collection of SAR product types and variants. Together with instrument calibration, checkout and tuning of the SAR processor was one of the major tasks of the commissioning phase with respect to product verification and validation. This paper summarizes the key activities and exposes the achievements obtained with respect to focusing quality. View full abstract»

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  • TerraSAR-X Image Products: Characterization and Verification

    Publication Year: 2008 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (72 KB)  

    The German SAR satellite TerraSAR-X has been launched in June 2007. The instruments flexibility and the capabilities of the operational TerraSAR-X Multi-Mode SAR Processor (TMSP) allow a huge variety of product types and variants for numerous applications. Already within weeks from the launch, the operational modes were checked out and the full variety of basic products was generated and delivered by the TMSP. This allowed to start the SAR product characterization early, providing major inputs to the overall SAR system characterization and calibration. Also the optimization of instrument commanding and SAR data processing is widely based on the SAR product characterization results. However, the image products are the outcome of an all-embracing workflow including ordering, commanding, instrument operation, reception, screening, processing, archival and delivery. Prerequisites for complete product verification are a stable and settled system and verified input products. Thus the SAR basic product verification could only be the final step of the very successful TerraSAR-X calibration and verification activities. The operationally available level 1b product portfolio and the product format are presented. Similarities and differences between the product variants are pointed out. Besides the basic products also experimental products, which may be available in a later project phase, are introduced. Product performance parameters for varying acquisition parameters are presented. Handling and interpretation of the TerraSAR-X SAR data products is addressed. View full abstract»

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  • Analysis of Spatial Statistics in Polarimetric SAR Data Using Wavelet Signatures

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1396 KB)  

    The Wavelet Polarization Signature (WASP) is a formalism, recently introduced in the literature, for analysing in SAR imagery the dependences of texture measures afforded by wavelet frames on scale and polarization state. In this paper experiments are reported where WASP analysis is applied for the spatial statistics characterization of targets of interest in land and marine applications. Results indicate that the effects related to the behaviour of spatial statistics under a change in polarization state, which were predicted theoretically, do indeed occur and could be potentially useful in segmentation and target detection problems exploiting polarimetric texture diversity. View full abstract»

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  • Polarimetric SAR Coherent Change Detection

    Publication Year: 2008 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (724 KB)  

    In repeat pass interferometric SAR man-made scene changes may be detected by identifying regions of low coherence. The ability to detect such changes however, depends on other sources of decorrelation such as environment effects and baseline decorrelation. Recently a Log Likelihood Change Statistic (LLCS) has been derived by formulating the problem in a Bayesian hypothesis testing framework. In this paper the LLCS is extended to exploit the additional information available in polarimetric SAR imagery. It is shown through simulation and application to experimental data that the fully polarimetric LLCS significantly improves the ability to detect scene changes. View full abstract»

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  • Statistical evaluation and bias removal of multi-look effect on Entropy/ alpha/Anisotropy in polarimetric target decomposition

    Publication Year: 2008 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1309 KB)  

    Entropy, alpha and anisotropy (H/alpha/A) of the polarimetric target decomposition has been an effective and popular tool for polarimetric SAR image analysis and for geophysical parameter estimation. However, multi-look processing can severely affects the values of these parameters. In this paper, Monte Carlo simulation is used to evaluate the multi-look effect on these parameters for various media of grass, forest and urban. Due to insufficient averaging, entropy is underestimated and anisotropy is overestimated. We also found that the bias in Alpha angle can be either under or overestimated depending on scattering mechanisms. Based on simulation results, efficient bias removal procedures have been developed. In particular, the entropy bias can be precisely corrected independent of radar frequency and SAR systems. Data from L-band DLR/E-SAR and L-band JPL/AIRSAR, and X-band PI-SAR data are used for demonstration. View full abstract»

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