Presented by Fabrizio Lombardini
|Sunday, 27 September, 05:00 - 09:00 PDT (Los Angeles, US Pacific Time)|
|Sunday, 27 September, 14:00 - 18:00 CEST (Central Europe Summer Time)|
|Sunday, 27 September, 20:00 - 00:00 CST (China Standard Time)|
Thanks to the capability of providing direct physical measurements, synthetic aperture radar (SAR) Interferometry allowing generation of digital elevation models and monitoring displacements to a mm/year order, is one of the techniques that have most pushed the applications of SAR to a wide range of scientific, institutional and commercial areas, and it has provided significant returns to the society in terms of improvements in risk monitoring. SAR images relative to a same scene and suitable for interferometric processing are today available for most of the Earth, and their number is exponentially growing. Archives associated to SAR spaceborne sensors are filled by data collected with time and observation angle diversity (multipass-multibaseline data); moreover, current system trends in the SAR field involve clusters of cooperative formation-flying satellites with capability of multiple simultaneous acquisitions (tandem or multistatic SAR systems), airborne systems with multibaseline acquisition capability in a single pass are also available, and unmanned air vehicles with capability of differential monitoring of rapid phenomena are being experimented.
In parallel, processing techniques have been developed, evolutions of the powerful SAR Interferometry, aimed at fully exploiting the information lying in such huge amount of multipass-multibaseline data, to produce new and/or more accurate measuring and information extraction functionalities. Focus of this tutorial is on processing methods that, by coherently combining multiple SAR images at the complex (phase and amplitude) data level, differently from phase-only Interferometry, allow improved or extended imaging and differential monitoring capabilities, in terms of accuracy and unambiguous interpretation of the measurements.
The tutorial, along the lines of previous issues but in a renewed format, will cover in particular interrelated techniques that have shaped in the recent years an emerged branch of SAR interferometric remote sensing, Tomographic SAR Imaging and Information Extraction; this is playing an important role in the development of next generation of SAR products and will enhance the application spectrum of SAR systems in Earth observation, in particular for the analysis and monitoring of complex scenarios such as urban/critical infrastructure and forest or more generally volumetric scenes, e.g. ice layers and snowpacks.
After briefly recalling the basic concept of SAR Interferometry, multibaseline/multipass Tomographic SAR techniques will be framed, presented, and discussed with respect to the specific applications. These techniques are 1) Multibaseline 3D Tomography, furnishing the functionality of layover scatterers elevation separation, to locate different scatterers interfering in the same pixel in complex surface geometries of man-made structures, causing signal garbling in high frequency SARs, and the functionality of full 3D imaging of volumetric scatterers, to provide a profiling of the scattering distribution also along the elevation direction for unambiguous extraction of physical and geometrical parameters in geophysical structures with vertical stratification, sensed by low frequency SARs; 2) Multipass 4D (3D+Time) and higher order Differential Tomography of multiple layover scatterers with slow deformation motions, a more recent and very promising Multidimensional Imaging mode, crossing the bridge between Differential Interferometry and Multibaseline Tomography.
Basic concepts, signal models and most diffused processing techniques for 3D/4D Tomographic SAR Imaging will be described in the array beamforming processing i.e. spatial spectral estimation framework, Fourier based, and of super-resolution kind (adaptive, and model-based). Live demonstration of these Tomographic algorithms and of their behavior will be carried out using simple simulation Matlab codes. A number of experimental results obtained with real data, multibaseline single-pass and multipass airborne, and multipass spaceborne, in X-, C-, L-, and P-band (in particular AER-II, E-SAR, ERS-1/2, COSMO-SkyMed, TerraSAR-X), over infrastructure, urban, forest, and ice areas, will be presented to show current achievements in real cases and the important application potentials of these emerged techniques. Recent new trends in the area will be finally mentioned, including hints to compressive sensing Tomography, and to concepts of higher-order ("5D") Tomography robust to temporal decorrelation and Differential Tomography of non-uniform deformation motions.