Wide band SAR sub-band splitting and inter-band coherence measurements

Range resolution of SAR images is determined by transmitted radar signal bandwidth. Most recent SAR sensors use wide band signals in order to achieve metric range resolution, whereas metric azimuth resolution can be achieved in spotlight mode. As an example, ENVISAT ASAR sensor uses a 15-MHz bandwidth chirp whereas TerraSAR-X spotlight mode uses signals having a 150-MHz bandwidth leading to a potentially 10 times higher resolution. One can also take advantage of wide band to split the full band into sub-bands and generate several lower resolution images from a single acquisition, each being centred on slightly different frequencies. These sub-images can then be used in a classical interferometric process to measure inter-band coherence of a given scene. This inter-band coherence reveals scatterers keeping a stable-phase behaviour along with frequency shift. A simple coherence model derived from Zebker model for randomly distributed surface scatterers is proposed. Examples are presented, showing that scatterers can have a behaviour that deviates from the model, leading to a new information channel.WiMCA - Wide Band interferometric Multichromatic Analysi

Status of SAR-Interferometry and its Applications at DLR

Interferometric SAR (INSAR) is a very promising technique in radar remote sensing. The Institute of Radio Frequency Technology and the German Remote Sensing Data Center of DLR have been working in this field for several years. The activities include all main processing steps: the formation of single look complex images, the generation of interferograms, the coherence estimation, the phase-unwrapping, the conversion of phase to height and the geocoding of the final DEM

Multi-Modal and Multi-Temporal Data Fusion: Outcome of the 2012 GRSS Data Fusion Contest

The 2012 Data Fusion Contest organized by the Data Fusion Technical Committee (DFTC) of the IEEE Geoscience and Remote Sensing Society (GRSS) aimed at investigating the potential use of very high spatial resolution (VHR) multi-modal/multi-temporal image fusion. Three different types of data sets, including spaceborne multi-spectral, spaceborne synthetic aperture radar (SAR), and airborne light detection and ranging (LiDAR) data collected over the downtown San Francisco area were distributed during the Contest. This paper highlights the three awarded research contributions which investigate (i) a new metric to assess urban density (UD) from multi-spectral and LiDAR data, (ii) simulation-based techniques to jointly use SAR and LiDAR data for image interpretation and change detection, and (iii) radiosity methods to improve surface reflectance retrievals of optical data in complex illumination environments. In particular, they demonstrate the usefulness of LiDAR data when fused with optical or SAR data. We believe these interesting investigations will stimulate further research in the related areas

ARES: a new refelctive/emissive imaging spectrometer for terrestrial applications

This paper introduces application possibilities for a new airborne imaging spectrometer, the ARES (Airborne Reflective Emissive Spectrometer)currently being built by Integrated Spectronics, Sydney, Australia, and co-financed by DLR German Aerospace Center and the GFZ GeoResearch Center Potsdam, Germany. This instrument shall feature a high performance over the entire optical wavelength range and will be available to the scientific community from 2004 on. The ARES sensor will provide approx. 160 channels in the solar reflective region (0.45-2.45 µm) and the thermal region (8-13 µm). It will consist of four co-registered individual spectrometers, three of them for the reflective and one for the thermal part of the spectrum. The spectral resolution will be between 12 and 15 nm in the solar wavelength range and less then 150 nm in the thermal. ARES will be used mainly for environmental applications in terrestrial ecosystems. The thematic focus is thought to be on soil sciences, geology, agriculture and forestry. Limnologic applications should be possible but will not play a key role in the thematic applications. For all above mentioned key application scenarios the spectral response of soils, rocks, and vegetation as well as their mixtures contain the valuable information to be extracted and quantified. The instrument will be offered to the scientific community on a commercial basis as well as through planned national and international programs from 2005 onwards. One of the major goals of ARES is to prepare the ground for a future global spaceborne hyperspectral mission