Analyzing Tomographic SAR Data of a Forest With Respect to Frequency, Polarization, and Focusing Technique

Frey, Othmar; Meier, Erich

doi:10.1109/tgrs.2011.2125972

Cited by 80 publications

(32 citation statements)

References 44 publications

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“…The difference between the precision of the vegetation height estimation with the vertical or with the horizontal transmit polarization can be analyzed with the suggestion of different analysis [30], [31], [32] that |S HH | 2 ≥ |S V V | 2 ≥ |S HV | 2 and that S HH S HV ≃ S V V S HV ≃ 0 [17] for forest grounds. These relations have been confirmed with recent tomographic analysis such as [35], [36] and are consistant with the analyzed examples of this paper. In that case the difference of the polarization characteristics of the waves backscattered by the volume or by the ground can only depend of their degrees of polarization since, for both the vertical and the horizontal transmit polarizations, the main polarization state of the backscattered waves by both media are identical.…”

Section: B Influence Of the Transmit Polarizationsupporting

confidence: 89%

Vegetation Height Estimation Precision With Compact PolInSAR and Homogeneous Random Volume Over Ground Model

Arnaubec

Roueff

Dubois-Fernandez

et al. 2014

IEEE Trans. Geosci. Remote Sensing

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Analyzing the precision of vegetation height estimation with compact (i.e., single transmit instead of dual transmit) polarimetric interferometric synthetic aperture radar (PolInSAR) with the homogeneous random volume over ground model can help justify the use of this type of radar rather than using the full PolInSAR. However, since compact PolInSAR provides less information than full PolInSAR, a loss of precision in the vegetation height estimation is expected, which can depend on the single transmit polarization. The adaptation of the Cramer-Rao bound (CRB) derived for full PolInSAR in our earlier work to compact PolInSAR measurement provides a general methodology to characterize this loss of precision. Indeed, the CRB is a lower bound of the variance of unbiased estimators that does not depend on the choice of a particular estimation method. We illustrate this methodology for P-band measurements with three synthetic examples chosen for their variability of polarimetric responses. For these examples, it is shown that there can exist a large set of transmit polarizations for which the loss of precision described by the CRB is small (smaller than a factor 2) although there also exist transmit polarizations for which the loss can be large (about a factor 100). This loss of precision is compared with the large dependency of the precision to the vegetation height estimation that can be observed with the vegetation height (more than a factor 100 in the precision described by the CRB) when all the other parameters of the vegetation, ground, and radar system are constant. Keywords:Compact polarimetry (CP) ; Cramer-Rao bound (CRB) ; polarimetric SAR interferometry (PolInSAR) ; random volume over ground (RVoG) model Philippe Réfrégier is presently professor at the Ecole Centrale de Marseille and member of the Fresnel Institute in which he is presently working on statistical optics, image processing and remote sensing. He has published two French books, two English books and more than 140 articles in international journals in optics, pattern recognition, statistical physics, image processing and remote sensing. He is OSA and EOS fellow.

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Section: B Influence Of the Transmit Polarizationsupporting

confidence: 89%

Vegetation Height Estimation Precision With Compact PolInSAR and Homogeneous Random Volume Over Ground Model

Arnaubec

Roueff

Dubois-Fernandez

et al. 2014

IEEE Trans. Geosci. Remote Sensing

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“…The resolution along the so-called azimuth (along track) direction, which corresponds to the flight direction of the sensor, is achieved by creating a synthetic array just with repeated pulse emissions during the flight. More expensively, N parallel flights have to be carried out to achieve sampling in the orthogonal, across track, direction (Tebaldini 2010;Frey and Meier 2011;Tebaldini and Rocca 2012;Nannini et al 2012). This acquisition is N times more expensive in the case of airplanes, but in the case of satellites, exploiting the stationarity of the target, one can inexpensively profit of the many possible successive satellite passes.…”

Section: Introductionmentioning

confidence: 99%

Airborne and satellite SAR tomography: a tool to investigate forests and glaciers structures

2016

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Microwave radiations below say 1250 MHz penetrate forests, dry ice and rocks. The use of airborne or satellite borne microwave sensors to image the subsurface with significant penetration is thus of high interest to analyse wide areas or even to make global surveys. Due to the large distance from the targets, the antenna has to be synthesized using a progressive scan and illuminating the targets from different positions. The radar returns are then properly combined using a computer. The position of the sensor has to be known to a fraction of a wavelength. This is rather easy to obtain if the sensor flies along a well-characterized track (synthetic aperture radar (Bamler and Hartl, 1998)). The creation of the across track aperture is much more difficult. It can be done by using many flights or orbits, which positions, however, need to be extremely well known. We show that this can be obtained by exploiting the characteristics of the targets. We will present the results obtained with airborne campaigns using polarimetric radars on boreal and tropical forests, which were carried out in order to estimate the above ground biomass. Campaigns have also been carried out over glaciers, to estimate the structure of the subsurface. We will then introduce two new satellites, Biomass and SAOCOM companion, planned to be deployed by the European Space Agency in the forthcoming years. Exploiting the results of the ad hoc airborne campaigns, the results to be obtained with these systems are simulated and presented. ARTICLE HISTORY

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“…It shows the mutual coupling between transmit and receive antennas, the scattering of the signal by plants, and the reflection by the ground. Thus the attenuation of plants with different polarization can be analyzed by the time-domain response [17,18].…”

Section: Introductionmentioning

confidence: 99%

Calculation of Differential Propagation Constant Determined by Plant Morphology Using Polarimetric Measurement

2014

International Journal of Antennas and Propagation

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The morphology of vegetation greatly impacts propagation of polarized electromagnetic wave. In order to validate this phenomenon, the mathematical relation between the differential propagation constant of forest vegetation and of its polarized echo is quantitatively derived by using backscattering power profile. The fluctuation of differential propagation constant with frequency is analyzed by combining the morphological characteristics of vegetation. The accurate copolarized data of 3-10 GHz frequency-domain of small trees are obtained by indoor wideband polarimetric measurement system. The results show that morphological characteristics of vegetation at different frequencies can be obtained by the differential propagation constant of polarized electromagnetic wave. At low frequencies, the plants with structural features presented oriented distribution. However, the plants show random distribution of the echoes at higher frequencies, which is mainly from the canopy. The research provides important information to choose the coherence models employed in the parameters retrieval of vegetations.

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Analyzing Tomographic SAR Data of a Forest With Respect to Frequency, Polarization, and Focusing Technique

Cited by 80 publications

References 44 publications

Vegetation Height Estimation Precision With Compact PolInSAR and Homogeneous Random Volume Over Ground Model

Vegetation Height Estimation Precision With Compact PolInSAR and Homogeneous Random Volume Over Ground Model

Airborne and satellite SAR tomography: a tool to investigate forests and glaciers structures

Calculation of Differential Propagation Constant Determined by Plant Morphology Using Polarimetric Measurement

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