Papers by Nicola Veneziani
This work investigates the possibility of performing target analysis through the Multi-Chromatic ... more This work investigates the possibility of performing target analysis through the Multi-Chromatic Analysis (MCA), a technique that basically explores the information content of sub-band images obtained by processing portions of the range spectrum of a synthetic aperture radar (SAR) image. According to the behavior of the SAR signal at the different sub-bands, MCA allows target classification. Two strategies have been experimented by processing TerraSAR-X images acquired over the Venice Lagoon, Italy: one exploiting the phase of interferometric sub-band pairs, the other using the spectral coherence derived by computing the coherence between sub-band images of a single SAR acquisition. The first approach introduces the concept of frequency-persistent scatterers (FPS), which is complementary to that of the time-persistent scatterers (PS). FPS and PS populations have been derived and analyzed to evaluate the respective characteristics and the physical nature of the targets. Spectral coherence analysis has been applied to vessel detection, according to the property that, in presence of a random distribution of surface scatterers, as for open sea surfaces, spectral coherence is expected to be proportional to sub-band intersection, while in presence of manmade structures it is preserved anyhow. First results show that spectral coherence is well preserved even for very small vessels, and can be used as a complementary information channel to constrain
Documenta Ophthalmologica Proceedings Series, 1993
This paper describes research within the CNR’s Progetto Finalizzato ‘Tecnologie Biomediche e Sani... more This paper describes research within the CNR’s Progetto Finalizzato ‘Tecnologie Biomediche e Sanitarie’, subproject ‘ultrasounds’. The aims of this study were as follows: (1) in the field of digital processing of B-scan images, aimed at tissue characterization by means of texture analysis; and (2) in the design and implementation of an echographic unit for ophthalmology, with advanced technical features. The prototype of the electronic interface between a 64-element linear curtain transducer, at 10 MHz, and the videofrequency section of the last unit is working actually, included in a commercial echograph produced by ESAOTE-Biomedica. In this paper, experimental results obtained with the developed hardware are shown. The integration of hardware and software modules within a single advanced unit is currently in progress. It will be based on a personal computer, supported by a video interface and by the hardware modules now under test.
The design concept and operation of a digital processing algorithm for satellite SAR image data a... more The design concept and operation of a digital processing algorithm for satellite SAR image data are discussed. The algorithm employs a range-Doppler approach, in which the two-dimensional SAR data are decomposed into one-dimensional range and azimuth components, which are then processed in the frequency domain using matching filters. The initial signal processing, the estimation of Doppler parameters, the correction of range walk, the application of quality measures, and the speckle-reduction procedures are outlined; and data and sample images from analyses of SIR-B images are presented. Also examined are the potential improvements in computation speed obtainable with a hypercube parallel implementation of the algorithm: the feasibility of real-time image processing is indicated.
Documenta Ophthalmologica Proceedings Series, 1988
The authors report their continuing research aimed at computer aided echography by processing B-s... more The authors report their continuing research aimed at computer aided echography by processing B-scan videofrequency images with SGLD method. They find a reduction of subjectivity of diagnosis of pathology.
[Proceedings] IGARSS'91 Remote Sensing: Global Monitoring for Earth Management
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The Sixth Distributed Memory Computing Conference, 1991. Proceedings
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12th Canadian Symposium on Remote Sensing Geoscience and Remote Sensing Symposium,
This paper describes the techniques developed to process SAR data obtained by the CNES X-Band VAR... more This paper describes the techniques developed to process SAR data obtained by the CNES X-Band VARAN-S Airborne SAR during the Agrisar-86 campaign on the Italian test-site. The processing has been performed starting from the sensor "raw-data" , whose main characteristics are the analogical range compression, the azimuthal pre filtering and decimation, all executed in real-time onboard.
IEEE Geoscience and Remote Sensing Letters, 2014
ABSTRACT The multichromatic analysis (MCA) can be applied to interferometric pairs of synthetic a... more ABSTRACT The multichromatic analysis (MCA) can be applied to interferometric pairs of synthetic aperture radar (SAR) images processed at range subbands and consists of exploring the phase trend of each pixel as a function of the different central carrier frequencies. The phase of stable scatterers linearly evolves with the subband central frequency, with a slope proportional to the absolute electromagnetic path difference that can be estimated and used for both phase unwrapping and height computation. MCA has been theoretically evaluated and tested on airborne wideband SAR data, appearing optimally suited for the new generation of satellite sensors, which operate with larger bandwidths than previously available instruments, generally limited to few tens of megahertzs. In this letter, we illustrate MCA application to satellite SAR data acquired in spotlight mode over the Uluru monolith in Australia. The topographic measurements derived through MCA on the monolith are compared with those provided by a high-resolution digital elevation model from optical stereo imagery. The theoretical parametric model describing the MCA performances according to the processing parameters is also validated.
The Multi-Chromatic Analysis, as introduced in [1], consists in performing a spectral decompositi... more The Multi-Chromatic Analysis, as introduced in [1], consists in performing a spectral decomposition of each image of an interferometric pair. Spectral decomposition is performed extracting sub-bands in range frequency domain, each extracted sub-band leading to a range sub-look of the observed scene, here named a chromatic view, centered on its own carrier frequency but at lower range resolution. From a single interferometric pair, one can then generate several interferometric pairs exploring the frequency band centered on the carrier frequency of the initial acquisitions. The interferometric phase of spectrally-stable scatterers evolves linearly with the sub-band central frequency, the slope being proportional to the absolute optical path difference. Unlike the standard “monochromatic” InSAR approach, this new multi-chromatic technique allows performing spatially independent and absolute phase unwrapping (PU). Potential applications for the study of spectrally-stable targets include topographic measurements, atmospheric research or urban monitoring. The technique appears optimally suited for the new generation of satellite sensors, which operate with large bandwidths to reach metric range resolution. Previous work on the subject has started demonstrating the practical feasibility of the technique by using a set of SAR data collected by the airborne AES-1 radar interferometer, operating at X-band by multi-channel electronics, which provides a total radar bandwidth of 400 MHz. This work presents first successful applications of the technique using TerraSAR-X Spotlight interferometric dataset acquired on the desert area of Ayers Rock (Australia), which satisfies the processing requirements derived from previous investigations. In particular, it was possible to validate the use of MCA for performing absolute PU as well as for height measurement on a pixel-by-pixel basis. However, height measurements still needs a calibration procedure through independent measurements (e.g. reference points) due to the impact of atmospheric signals as well as orbital errors. A height surface derived by MCA is presented and compared to the reference SRTM DEM.
The Multi-Chromatic Analysis (MCA) consists of performing sub-bands splitting in range frequency ... more The Multi-Chromatic Analysis (MCA) consists of performing sub-bands splitting in range frequency domain, thus generating chromatic views of lower range resolution, centered at different carrier frequencies. Multi-chromatic interferograms can be then generated by coupling chromatic views coming from an interferometric pair of SAR images. The interferometric phase of spectrally-stable scatterers evolves linearly with the sub-band central frequency, the slope being proportional to the absolute optical path difference. Unlike the standard “monochromatic” InSAR approach, this new technique allows performing spatially independent and absolute phase unwrapping (PU). Potential applications for the study of spectrally-stable targets include topographic measurements, atmospheric research or urban monitoring. The technique appears optimally suited for newgeneration, wide-band, high-resolution satellite SAR sensors. This work presents first successful applications of the technique using both TerraSAR-X (TSX) and COSMO/SkyMed (CSK) spotlight data. In particular, we provide results concerning the use of MCA for performing absolute PU as well as for height measurement on a pixel-by-pixel basis. Moreover, the impact of coregistration procedure on the MCA-based inference is investigated.
Practical parallel computing: status and prospects, 1991
Parallel Computing, Problems Methods and Applications, 1992
International Geoscience and Remote Sensing Symposium (IGARSS), 2012
ABSTRACT The Multi-Chromatic Analysis can be applied to interferometric pairs of SAR images proce... more ABSTRACT The Multi-Chromatic Analysis can be applied to interferometric pairs of SAR images processed at range sub-bands, and consists of exploring the phase trend of each pixel as a function of the different central carrier frequencies. The phase of stable scatterers evolves linearly with the sub-band central wavelength, with a slope proportional to the absolute e.m. path difference. The technique appears optimally suited for the new generation of satellite sensors, which operate with larger bandwidths than previously available instruments, generally limited to few tens of MHz. A first experiment on satellite data was carried out by processing a spotlight interferometric pair of images acquired by TerraSAR-X on the well-known Uluru monolith in Australia. In the present work, we illustrate MCA processing on SAR data acquired over the same site by the COSMO-SkyMed constellation. The topographic profile of the monolith is successfully reconstructed. Furthermore, the results are also compared with those previously derived by processing TerraSAR-X data.
Abstract: This study examines the relationship between temperature and chlorophyll-a in the Gulf ... more Abstract: This study examines the relationship between temperature and chlorophyll-a in the Gulf of Manfredonia, a coastal zone on the Italian side of the Adriatic Sea. During May 2003, images of [chl-a] and sea surface temperature of the test area have been collected by ...
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Papers by Nicola Veneziani