Hannah Joerg

Dual-polarimetric agricultural change analysis of long baseline TanDEM-X time series data

The standard TanDEM-X baselines have been designed to optimize the high resolution global Digital Elevation Model (DEM) generation. However, during the Science Phase of the mission longer baselines are available. This allows interferometric measurements with a higher vertical sensitivity, more appropriate for agricultural applications, where the crop heights are too small to be properly detected and analyzed with the standard baselines. This paper evaluates the use of the experimental long baseline TanDEM-X acquisitions for the monitoring of the agricultural changes in dual-pol single-pass interferometric time series.

Spatial and temporal characterization of agricultural crop volumes by means of polarimetric SAR tomographyatc-band

In this paper, agricultural crop volumes are analysed using (polarimetric) tomographic SAR methodologies. A procedure for the separation of the ground and volume multibaseline coherences is proposed. This separation is used in particular to investigate the polarization dependency of the vegetation vertical structure in order to get first insights about orientation effects. This analysis has been carried out for different crops and on different development stages. The presented results have been obtained by processing a multibaseline fully polarimetric data set purposely acquired at C-band by the DLRs airborne sensor F-SAR in 2014.

On the Separation of Ground and Volume Scattering Using Multibaseline SAR Data

In forest and agricultural scattering scenarios, the backscattered synthetic aperture radar (SAR) signature consists, depending on the frequency, of the superposition of ground and volume scattering contributions. Using multibaseline SAR data, SAR tomography techniques allow resolving contributions occurring at different heights. Two algorithms for the separation of ground and volume scattering are compared with respect to their ability to provide a coherent volume component that can be further used for parameter inversion, both of them requiring only the a priori known ground topography. Once the volume-only coherences are available, the total ground and volume scattering powers are estimated by means of a least squares fitting. The objective of this letter is to quantitatively evaluate the performance of this estimation by means of a Monte Carlo analysis with simulated data focusing on the impact of vertical resolution, errors in the knowledge of the ground topography and phase calibration residuals.

First study on holographic SAR tomography over agricultural crops at C-/X-band

Recently, the 3-D backscattering distribution of forests and ice bodies has been factor of study with the HoloSAR imaging mode, showing its capabilities to obtain 3-D imaging reconstructions of volumes over 360° at very high resolution. In this paper, the first assessment of agricultural crops in the holographic SAR tomography (HoloSAR) mode is presented. The goal of this research is to investigate the retrieval of the three-dimensional backscattering of crop fields as a function of the azimuthal aspect angle and the tomographic constellation. To that end, a HoloSAR campaign was conducted at X-/C-band by DLRs F-SAR sensor in Wallerfing, Germany. The experimental results of this study show 2-D and 3-D polarimetric images, where the co-polar phase is analyzed qualitatively giving some indications about the kind of scattering mechanisms.