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For SAR (Synthetic Aperture Radar) system, the high resolution (range/azimuth) and wide swath are required constantly. It is challenge to achieve both high azimuth resolution and wide swath imaging for spaceborne SAR system because it poses contradicting requirements for pulse repetition frequency. The technique of the multiple receive apertures and digital beam forming is utilized to overcome the...
This paper is dedicated to the “40 Years of Ocean Remote Sensing — a Session to Honor W. Alpers on the Occasion of his 80th Birthday”. In this paper, a list of Alpers' research contributions in understating the atmospheric gravity waves and oceanic internal waves are highlighted along with up-to-date research finding in these fields. On the atmospheric side, we presented the SAR observation of atmospheric...
We analyzed more than 5000 synthetic aperture radar (SAR) images from ERS 1/2, ENVISAT, ALOS-1, and Sentinel-1A with respect to marine oil pollution in two regions of interest (ROIs) in Indonesian waters. Both normalized spill number and normalized mean polluted area indicate that the marine oil pollution in the ROIs generally is of different origin: while ship traffic appears to be the main source...
This paper proposed a new concept of optical counterpart of radar system. Due to the difference between wavelength of microwave and light, we can build an optical counterpart of a radar system in reduced dimensions with optical components and light in place of microwave. The radar system is equivalent to its optical counterpart in physical principle. As for a C-band radar system, the wavelength is...
The CNNs manifest outstanding performance in SAR ATR applications. The most widely used means for evaluation is to test them on a separate testing set. However, as there exists a strong correlation between the working conditions of the training and the testing sets, the reliability of the method degrades. We revealed the problem by training and testing the models with pure clutters, and found that...
Flood maps are indispensable to regional prioritization and effective resource distribution, and are required by policy makers, insurance firms, and disaster-relief agencies. SAR (Synthetic Aperture Radar) image classification is widely used for flood mapping, although the utilization of image texture has not been well explored. This study proposes a novel SAR-based flood mapping technique that uses...
In this study, the radar backscatter features of the shallow water topography of Subei bank in the Southern Yellow Sea are investigated using ENVISAT (Environmental Satellite) ASAR (advanced synthetic aperture radar) images. Different bathymetric features are found on SAR imagery, which correspond to sea surface imprints of tidal channels or sand ridges, respectively. Preliminary analysis demonstrates...
The side-looking imaging geometry of synthetic aperture radar (SAR) causes inevitable layover in SAR images. Separating the contributions from different scatterers has been the fundamental for many applications. It is typically solved by explicit inversion of the SAR imaging model to retrieve the scattering profile along the mixed dimension (elevation), which is otherwise known as SAR tomography....
Spaceborne SAR interferometry (InSAR) has the potential of detecting forest change on a global scale with fine (meter-level) spatial resolution as well as on a monthly/weekly basis regardless of day or night. This is significant to characterize the land-use change and its impact on climate change. In this paper, both single-pass and repeat-pass SAR interferometry from spaceborne sensors are combined...
Vegetation indices derived from optical and multispectral data, such as Enhanced Vegetation Index (EVI), have been widely used to monitor the health and productivity of vegetation. However, their use is limited in areas with persistent cloud-cover and inclement weather. Due to the all-weather observations provided by Synthetic Aperture Radar (SAR) sensors, an alternative would be to derive vegetation...
The most common polarimetric decompositions can only be computed for fully polarimetric data at the cost of reduced spatial resolution and areal coverage. In this paper, we analyze the potential of dual-pol SAR imagery for the monitoring of bivalve beds on intertidal flats. The normalized Kennaugh elements, which can be calculated from dual-pol data of any wavelength, are applied to deduce polarimetric...
In this paper, we propose a persistent scatterer clustering method for high-resolution structure displacement analysis. Persistent scatterer interferometry can monitor millimetric displacement of structures like bridges, buildings, and roads by analysis at persistent scatterers (PSs), pixels with high coherence in synthetic aperture radar (SAR) images. However, it requires great time and effort to...
As part of the Copernicus Programme, Sentinel 1 (S1) synthetic aperture radar (SAR) mission represents a unique monitoring tool whose potentialities for hydrological risk mitigation need to be evaluated. To this aim, S1-A derived soil moisture maps with high spatial resolution (100 m) and moderate temporal resolution (12 days) were assimilated within a time-continuous, spatially-distributed, physically-based...
In this paper we investigate the use of discriminative model learning through Convolutional Neural Networks (CNNs) for SAR image despeckling. The network uses a residual learning strategy, hence it does not recover the filtered image, but the speckle component, which is then subtracted from the noisy one. Training is carried out by considering a large multitemporal SAR image and its multilook version,...
The utility of synthetic aperture radar (SAR) data to produce flood delineation maps is well established. However, for what concerns urban settlements, flood mapping still represents a challenge, because the radar signatures of flooded urban pixels are generally ambiguous. As a matter of fact, flood mapping algorithms generally do not consider urban areas, thus producing a lot of missed detection...
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