Joint detection and localization of vessels at sea with a GNSS-Based multistatic radar

This paper addresses the exploitation of global navigation satellite systems as opportunistic sources for the joint detection and localization of vessels at sea in a passive multistatic radar system. A single receiver mounted on a proper platform (e.g., a moored buoy) can collect the signals emitted by multiple navigation satellites and reflected from ship targets of interest. This paper puts forward a single-stage approach to jointly detect and localize the ship targets by making use of long integration times (tens of seconds) and properly exploiting the spatial diversity offered by such a configuration. A proper strategy is defined to form a long-time and multistatic range and Doppler (RD) map, where the total target power can be reinforced with respect to, in turn, the case in which the RD map is obtained over a short dwell and the case in which a single transmitter is employed. The exploitation of both the long integration time and the multiple transmitters can greatly enhance the performance of the system, allowing counteracting the low-power budget provided by the considered sources representing the main bottleneck of this technology. Moreover, the proposed single-stage approach can reach superior detection performance than a conventional two-stage process where peripheral decisions are taken at each bistatic link and subsequently the localization is achieved by multilateration methods. Theoretical and simulated performance analysis is proposed and also validated by means of experimental results considering Galileo transmitters and different types of targets of opportunity in different scenarios. Obtained results prove the effectiveness of the proposed method to provide detection and localization of ship targets of interest

Sensitivity of the WorldView-2 satellite orthoimage horizontal accuracy with respect to sensor orientation method, number and distribution of ground control points, satellite off-nadir angles and strip length

Imagery acquired by the WorldView-2 (WV2) sensor is of potential interest to the Control with Remote Sensing (CwRS) Programme of the European Commission and therefore needs to be assessed. In details, the horizontal accuracy of the orthoimages which can be derived from WV2 imagery have to be concerned, recalling that in order to qualify WV2 as a Very High Resolution (VHR) prime sensor (i.e. a sensor suitable for measuring parcel areas to the accuracy requested by the Common Agriculture Policy - CAP regulation), the CwRS guidelines requires that the one-dimensional RMSE error (i.e. in the East and North components) measured on the external Check Points - CPs for any orthoimage should not exceed 2.5 m. This report summarizes the results regarding the orientation tests of the five WorldView-2 Panchromatic (WV2 PAN) images acquired over the JRC Maussane Test Site (Provence, Southern France), two Pan-sharpened (WV2 PANSHP) images (COSE_MODE_1) acquired over Cosenza Test Site (Southern Italy) and 9 Pan-sharpned (WV2 PANSHP) scenes (COSE_MODE_3) acquired over Cosenza Test Site (Southern Italy), carried out with Geomatica (PCI Geomatics), ERDAS Imagine 2011 and SISAR software, using both Rigorous model and Rational Polynomial Functions (RPFs) model with Rational Polynomial Coefficients (RPCs). The Hold-Out-Validation accuracy assessment method (HOV) was considered, computing the Root Mean Square Error (RMSE) of the residuals between the estimated and the reference positions of the Check Points (CPs) for each horizontal component (East, North) varying the number of the GCPs. In addition the Leave-One-Out Cross Validation (LOOCV) method was been used to identify possible outliers.JRC.H.4-Monitoring Agricultural Resource

Effects of the COVID-19 lockdown on glycaemic control in subjects with type 2 diabetes: the glycalock study

Aim: To assess the effect of the coronavirus disease 2019 (COVID-19) lockdown on glycaemic control in subjects with type 2 diabetes (T2D). Materials and Methods: In this observational, multicentre, retrospective study conducted in the Lazio region, Italy, we compared the differences in the HbA1c levels of 141 subjects with T2D exposed to lockdown with 123 matched controls with T2D who attended the study centres 1 year before. Basal data were collected from 9 December to 9 March and follow-up data from 3 June to 10 July in 2020 for the lockdown group, and during the same timeframes in 2019 for the control groups. Changes in HbA1c (ΔHbA1c) and body mass index (ΔBMI) during lockdown were compared among patients with different psychological well-being, as evaluated by tertiles of the Psychological General Well-Being Index (PGWBS). Results: No difference in ΔHbA1c was found between the lockdown and control groups (lockdown group −0.1% [−0.5%−0.3%] vs. control group −0.1% [−0.4%−0.2%]; p =.482). Also, no difference was found in ΔBMI (p =.316) or ΔGlucose (p =.538). In the lockdown group, subjects with worse PGWBS showed a worsening of HbA1c (p =.041 for the trend among PGWBS tertiles) and BMI (p =.022). Conclusions: The COVID-19 lockdown did not significantly impact glycaemic control in people with T2D. People with poor psychological well-being may experience a worsening a glycaemic control because of restrictions resulting from lockdown. These findings may aid healthcare providers in diabetes management once the second wave of COVID-19 has ended

The Italian open data meteorological portal: MISTRAL

At the national level, in Italy, observational and forecast data are collected by various public bodies and are often kept in various small, heterogeneous and non-interoperable repositories, released under different licenses, thus limiting the usability for external users. In this context, MISTRAL (the Meteo Italian SupercompuTing PoRtAL) was launched as the first Italian meteorological open data portal, with the aim of promoting the reuse of meteorological data sets available at national level coverage. The MISTRAL portal provides (and archives) meteorological data from various observation networks, both public and private, and forecast data that are generated and post-processed within the Consortium for Small-scale Modeling-Limited Area Model Italia (COSMO-LAMI) agreement using high performance computing (HPC) facilities. Also incorporated is the Italy Flash Flood use case, implemented with the collaboration of European Centre for Medium-Range Weather Forecasts (ECMWF), which exploits cutting edge advances in HPC-based post-processing of ensemble precipitation forecasts, for different model resolutions, and applies those to deliver novel blended-resolution forecasts specifically for Italy. Finally, in addition to providing architectures for the acquisition and display of observational data, MISTRAL also delivers an interactive system for visualizing forecast data of different resolutions as superimposed multi-layer maps

A radargrammetric orientation model for digital surface models generation from synthetic aperture radar high resolution imagery: applications with Cosmo-SkyMed and TerraSAR-X

Digital Surface and Terrain Models (DSMs/DTMs) have large relevance in some territorial applications, such as topographic mapping, spatial and temporal change detection, feature extraction and data visualization. DSMs/DTMs extraction from satellite stereo pair offers some advantages, among which low cost, speed of data acquisition and processing, surveys of critical areas, easy monitoring of wide areas, availability of several commercial software and algorithms for data processing. In particular, the DSMs generation from Synthetic Aperture Radar (SAR) imagery offers the significant advantage of possible data acquisition during the night and in presence of clouds. The availability of new high resolution SAR spaceborne sensors as COSMO-SkyMed (Italian), TerraSAR-X (German) and RADARSAT-2 (Canadian) offers new interesting potentialities for the acquisition of data useful for the generation of DSMs following the radargrammetric approach, based at least on a couple of images of the same area acquired from two different points of view as for the standard photogrammetry applied to optical imagery. The aim of this work was the development and the implementation of an original rigorous radargrammetric model for the orientation of SAR imagery, suited for the subsequent DSM generation. The model performs a 3D orientation based on two range and two zero-Doppler equations starting from SAR stereo pairs in slant range and zero-Doppler projection, acquired in SpotLight mode, that is at the highest resolution presently available (1 m ground resolution). The model has been implemented in SISAR (Software per Immagini Satellitari ad Alta Risoluzione), a scientific software developed at Geodesy and Geomatic Institute of the University of Rome “La Sapienza”. This software was at first devoted to the orientation of high resolution optical imagery, and in the last year it has been extended also to SAR imagery. Moreover a tool for the SAR Rational Polynomial Coefficients (RPCs) generation has been implemented in SISAR software, similarly to the one already developed for the optical sensors. The possibility to generate RPCs starting from a rigorous model sounds of particular interest since, at present, the most part of SAR imagery is not supplied with RPCs, although the Rational Polynomial Functions (RPFs) model is available in several commercial software. The RPCs can be an useful tool in place of the rigorous model in processes as the image orthorectification/geocoding or the DSMs generation, since the RPFs model is very simple and fast to be applied. The model implemented has been tested on COSMO-SkyMed and on TerraSAR-X SpotLight imagery, showing that a vertical accuracy at level of better than 3 m is achievable even with quite few Ground Control Points

Multi-transmitter ship target detection technique with GNSS-based passive radar

The exploitation of the Global Navigation Satellite Systems (GNSS) as transmitters of opportunity in passive radar systems for maritime surveillance is particularly attractive because of the main advantages consisting in a global coverage (even in open sea) and in the availability of multiple sources (different satellites and constellations). The main drawback stays in the restricted power budget provided by navigation satellites. This characteristic makes necessary to conceive, define and develop detection techniques able to overcome such limitation. To this aim this work proposes a range-Doppler domain processing technique able to integrate over long time intervals the returns from a moving target illuminated by multiple GNSS transmitters. Several examples are shown to demonstrate the effectiveness of the proposed approach

RADARGRAMMETRIC DIGITAL SURFACE MODELS GENERATION FROM TERRASAR-X IMAGERY: CASE STUDIES, PROBLEMS AND POTENTIALITIES

The interest for the radargrammetric approach to Digital Surface Models (DSMs) generation has been growing in last years thanks to the availability of very high resolution imagery acquired by new SAR (Synthetic Aperture Radar) sensors, as COSMO-SkyMed, Radarsat-2 and TerraSAR-X, which are able to supply imagery up to 1 m ground resolution. DSMs radargrammetric generation approach consists of two basic steps, as for the standard photogrammetry applied to optical imagery: the imagery (at least a stereo pair) orientation and the image matching for the generation of the points cloud. The steps of the radargrammetric DSMs generation have been implemented into SISAR (Software per Immagini Satellitari ad Alta Risoluzione), a scientific software developed at Geodesy and Geomatics Institute of the University of Rome “La Sapienza”. Moreover, starting from the radargrammetric orientation model, a tool for the Rational Polynomial Coefficients (RPCs) for SAR images have been implemented. The possibility to generate RPCs, re-parametrizing a rigorous orientation model through a standardized set of coefficients which can be managed by a Rational Polynomial Coefficients (RPFs) model (similarly to optical high resolution imagery) sounds of particular interest since, at present, the most part of SAR imagery (except from Radarsat-2) is not supplied with RPCs, although the corresponding RPFs model is available in several commercial software. In particular the RPCs model has been used in the matching process and in the stereo restitution for the DSMs generation, with the advantage of shorter computational time. This paper discusses the application and the results of the implemented algorithm for radargrammetric DSMs generation from TerraSAR-X SpotLight imagery, acquired in Spotlight mode over Trento (Northern Italy). Urban and extra-urban (forested, cultivated) areas were considered in two different tiles, and a final overall accuracy ranging from 4.5 to 6 meters was achieved as regards the point clouds, enough well distributed independently from the land cover; moreover, it was highlighted the benefit to filter the originally derived points cloud with a global DSM as SRTM DEM, what leads to an accuracy improvement of about 20% paying a loss of matched points of about 10 %