The Italian open data meteorological portal: MISTRAL

AbstractAt 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

Algoritmi di matching per estrazione di DSM in aree urbane da immagini satellitari ad alta risoluzione

Thanks to the very high resolution and the good radiometric quality of the images acquired by GeoEye-1 and WorldView-1, it seems possible to extract a Digital Surface Model (DSM) at accuracy level, comparable to those coming from middle scale aerial products. The accuracy level of DSM is strictly related both to the image orientation and to the matching process. The orientation methods can be classified in two categories: physically-based models (also called “rigorous” models) based on the well-known collinearity equations and generic models that consist in purely analytic functions linking image to terrain coordinates in the form of ratios of polynomial thanks to known Rational Polynomial Coefficients – RPCs. As regards the image matching we can distinguish two basic techniques, the Area Based Matching (ABM) and the Feature Based Matching (FBM). In ABM method a small image window in the master image is opened and on the slave image a template window is shifted and in each position the high correlation coefficient is searched. Whereas FBM searches basic features (like corners, edges, lines, etc) in the two images and after analyzes the correspondence. In this work the accuracy level of DSM extracted with the scientific software SISAR developed by the University of Rome “La Sapienza” is evaluated; the software is able to orientate the high resolution satellite imagery and to generate the RPCs coefficients starting from own rigorous models. The image matching algorithms, implemented in SISAR software, are the FBM and the ABM, the latter is guided by RPC extracted “ad hoc” for the interest area. With this strategy two DSMs are extracted: the first is extracted from WorldView-1 stereopair and covers the Augusta area (Sicily), it is compared with the Lidar ground truth, the latter is extracted from GeoEye-1 stereopair, it covers the Rome area and a 3D vector cartography at 1:2000 scale is used as ground truth for DSM accuracy assessment

Definition of a radargrammetric model and application with COSMO-SkyMed imagery

The availability of new high resolution radar spaceborne sensors offers new interesting potentialities for the acquisition of data useful for the generation of Digital Surface Models (DSMs). Two different approaches may be used to generate DSMs from Synthetic Aperture Radar (SAR) data: the interferometric and the radargrammetric one. At present, the importance of the radargrammetric approach is rapidly growing due to the new high resolution imagery (up to 1 m GSD) which can be acquired by COSMO-SkyMed, TerraSAR-X and RADARSAT-2 in Spotlight mode. In this respect, it is well known that the two main steps for DSMs generation from SAR imagery according to the radargrammetric approach are the stereo pair ori-entation and the image matching. In this paper the topics related to image orientation of SAR stereo pairs in zero-Doppler geometry acquired by COSMO-SkyMed sensor in Spotlight mode are investigated. The defined and imple-mented model performs a 3D orientation based on two range and two zero-Doppler equations, allowing for the least squares estimation of some calibration parameters, related to satellite position and velocity and to the range measure. 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''. Starting from this model, based on geometric reconstruction, also a tool for the Rational Polynomial Coefficients (RPCs) generations has been implemented. To test the effectiveness of the new model, two stereo pairs, acquired by COSMO-SkyMed in Spotlight mode over the test sites of Mausanne (Southern France) and Merano (Northern Italy), have been orientated varying the number of Ground Control Points (GCPs) and independent Check Points (CPs). The results obtained clearly show that the geometric potentialities of COSMOSkymed SpotLight stereo pairs as regards 3D surface reconstruction is at the level of about 3 meter, even with quite few GCPs

DSM GENERATION FROM VERY HIGH OPTICAL AND RADAR SENSORS: PROBLEMS AND POTENTIALITIES ALONG THE ROAD FROM THE 3D GEOMETRIC MODELING TO THE SURFACE MODEL

The availability of new high resolution optical and radar spaceborne sensors offers new interesting potentialities for the acquisition of data useful for the generation of Digital Surface Models (DSMs). The accuracy level of DSM is strictly related both to the image orientation and to the matching process. As regards the image orientation, remote sensing community usually adopts two different types of models for High Resolution Satellite Imagery (HRSI): the physical sensor models and the generalized sensor models also called rigorous and Rational Polynomial Functions (RPFs) models respectively. In a scientific software developed by the research group of Geodesy and Geomatic Area of the University of Rome "La Sapienza" both rigorous and RPFs models are implemented, with a specific tool for the terrain-independent Rational Polynomial Coefficients (RPCs) generation; the software manages the imagery acquired by several optical sensors (EROS A, Ikonos, QuickBird, Cartosat-1, WorldView-1, GeoEye-1) and by the Italian SAR constellation COSMO-SkyMed. In the same software a facility for image matching is embedded. The Area Base Matching (ABM) is used, combined with the orientation model re-parametrized in terms of RPCs. In the present work some examples of models application and DSM generation are analyzed and discussed

DSM generation from high resolution COSMO-SkyMed imagery with radargrammetric model

The availability of new high resolution radar spaceborne sensors offers new interesting potentialities for the geomatics application: spatial and temporal change detection, features extraction, generation of Digital Surface (DSMs). As regards the DSMs generation from new high resolution data (as SpotLight imagery), the development and the accuracy assessment of method based on radargrammetric approach are topics of great interest and relevance. The aim of this investigation is the DSM generation from a COSMO-SkyMed Spotlight stereo pair with the radargrammetric technique. DSM generation procedure consists of two basic steps: the stereo pair orientation and the image matching. The suite for radargrammetric approach has been implemented in SISAR (Software per Immagini Satellitari ad Alta Risoluzione), a scientific software developed at the Geodesy and Geomatic Institute of the University of Rome “La Sapienza”. As regard the image matching the critical issue is the definition of a strategy to search the corresponding points; in SISAR software, an original matching procedure has been developed, based on a coarse-to-fine hierarchical solution with an effective combination of geometrical constrains and an Area Base Matching (ABM) algorithm

Radargrammetric generation of DEMs from high resolution satellite SAR imagery. A new tool for landslide hazard and vulnerability assessment

Spatial information acquisition and analysis tools play a fundamental role to supplying the information necessary to produce landslide inventories, which represent the foundations for quantifying landslide hazard and vulnerability. In this frame, fundamental data are Digital Surface Models (DSMs) and Digital Elevation Models (DEMs). The goal of this paper is just methodological, focused to illustrate the actual potentialities of DSMs generation from high resolution satellite Synthetic Aperture Radar (SAR) imagery with a radargrammetric stereo-mapping approach. The fundamental advantage of this approach is that it can work with just a couple of images (no matter for their coherence), which can be collected in a short time (half day to quite few days) thanks to the independence of satellite radar acquisition from weather (clouds), daylight and logistic constraints (as for airborne data collection). The suite for the DSMs generation through the radargrammetric approach has been implemented in SISAR (Software per Immagini Satellitari ad Alta Risoluzione), a scientific software developed at the Geodesy and Geomatic Institute of the University of Rome "La Sapienza". In order to demonstrate the radargrammetric mapping potentialities of high resolution SAR data, a test site was established in the area of Merano (Northern Italy), characterized by mixed morphology and land cover. The data available for the experiment were a COSMO-SkyMed SpotLight stereo pair and a LiDAR DEM, used as ground truth. An accuracy better than 3 m has been achieved in open areas and the implemented algorithm appears able to generate DSMs both over open and forested areas, where the accuracy is around 4 m. Therefore, radargrammetric generation of DSMs from high resolution satellite SAR imagery appears a valuable tool to supply topographic information for landslide inventories at different scales

A novel radargrammetric model and a RPCs generation strategy: application with COSMO-SkyMed and TerraSAR-X imagery

The topic of this paper is the definition of a geometric model for stereo pair orientation of SpotLight Synthetic Aperture Radar (SAR) imagery collected by the new high amplitude reso-lution radar sensors COSMO-SkyMed (Italian) and TerraSAR-X (German). The suite for radar-grammetric approach has been implemented in SISAR (Software per Immagini Satellitari ad Alta Risoluzione), a scientific software developed at the Geodesy and Geomatic Institute of the University of Rome “La Sapienza”. The rigorous model performs a 3D orientation based on two range and two zero-Doppler equations, allowing for the least squares estimation of some calibration parameters, related to satellite position and velocity and to the range measure. Starting from this model, according to a terrain independent scenario, an additional tool for the Rational Polynomial Coefficients (RPCs) generation has been implemented. In this last respect, it has to be noticed that only the imagery collected by the high amplitude resolution radar sensor RADARSAT-2 (Canadian) are presently supplied with RPCs. In order to validate the orientation model and the RPCs generation strategy, they were applied to imagery collected over three test sites. The first test site is a zone of Merano (Northern Italy), the second test site is the San Pietro Island (Sardinia, Italy), where SpotLight images were acquired by COSMO-SkyMed; the third test site is Hannover (Northern Germany), where imagery were acquired by TerraSAR-X. The results obtained and here discussed clearly show that the geometric potentialities of COSMO-SkyMed and TerraSAR-X stereo pairs as regards 3D surface reconstruction is at the level of 2-3 meter both with rigorous model and with generated RPCs

DSM generation from high resolution imagery: Applications with WorldView-1 and Geoeye-1

In this paper we present and discuss some results obtained with a new proprietary matching strategy for DSMs generation, which is implemented in the SISAR software developed at the Area di Geodesia e Geomatica - Università di Roma "La Sapienza". In order to assess the accuracy of the new strategy, some tests were carried out, using a stereo pair of Augusta coastal zone (Sicily, South Italy) acquired from WorldView-1 and one of the first available GeoEye-1 stereo pairs, which was acquired over Rome. The results show that an accuracy at the level of about 2 m is achievable in open areas with both WorldWiew-1 and GeoEye-1 stereo pairs, whereas higher errors are displayed in urban areas. For WorldWiew-1 the results are still acceptable, being the accuracy at the level of 3 meters, but for GeoEye-1 the DSM extracted over a very dense urban area are much worse, with an accuracy at the level of 8-10 meters. Nonetheless, the new matching strategy has been proven effective, performing always better if compared with the one implemented in a well known and largely used software as PCI-Geomatics

A radargrammetric orientation model and a RPCs generation tool for COSMO-SkyMed and TerraSAR-X high resolution SAR

The topic investigated in this paper is the stereo imagery orientation with regards to the SAR imagery in zero-Doppler geometry acquired by COSMO-SkyMed and TerraSAR-X in Spotlight mode. A rigorous orientation model, based on geometric reconstruction, had been already implemented in the scientific software SISAR; starting from this model, a tool for the Rational Polynomial Coefficients (RPCs) generation has been developed. The results of the orientation tests, performed using both rigorous and RPCs models, clearly show that the generated RPCs exploit the geometric potentialities of SpotLight stereo pairs as regards 3D surface reconstruction at the same accuracy level (about 3 meters) of the rigorous model