The scientific research of GGD Positioning Group was focused on GPS (then GNSS) data processing, exploring a variety of topics. Among them, the most relevant were, at first, the realization of a national reference frame through a GNSS permanent network and the definition and implementation of GNSS services for positioning and navigation at regional level; guidelines for the establishment and validation of such services were prepared to support their realization at regional level in Italy. GGD Positioning Group contributed to the realization of the actual Italian Reference Frame (legally adopted in 2012) through the Rete Dinamica Nazionale, and to the design of the GNSS service for positioning and navigation for Lazio Region. In 2010 at GGD it was invented the real-time variometric approach (VADASE) for GNSS seismology and vibration monitoring, after (2016) extended to navigation (Kin-VADASE) and (2019) integrated with point positioning (POWER). The effectiveness of VADASE was proved through the application to the catastrophic Japanese Tohoku-oki earthquake (M=9.0, 11 March 2011), when the first worldwide coseismic solution for two IGS stations (MIZU, USUD) was provided as soon as the data were available. VADASE has been implemented in the firmware of GR Series Leica Geosystems GNSS receivers since September 2015. More recent relevant research topics are related to GNSS real-time ionosphere sounding, through a side extension of the variometric approach (VARION), and to GNSS meteorology and total zenith delay assimilation in meteo forecast models. VARION has been implemented in 2018 in the NASA-JPL GDGPS system for contributing to tsunami early warning in the Pacific Ocean area, also participating in the working group for the GNSS Augmentation of Tsunami Early Warning (GATEW), established within GGOS Geohazards Focus Area. Investigation on low-cost and Android smartphone embedded GNSS receiver for monitoring and navigation were also recently developed, in the frame of the activities promoted by GSA (EU Global Navigation Satellite Systems Agency) Raw Measurements Task Force. Finally, since 2018, investigation on the integrated contribution of long GNSS coordinate time series, known tectonic setting and seismology for intermediate-term narrow-range earthquake prediction according to Neo-Deterministic Seismic Hazard Assessment (NDSHA) has been developed, with significant applications in Italy.
The scientific research of GGD Image Analysis Group was focused on Digital Surface Models (DSMs) and orthoimages generation from data acquired by new optical and SAR high resolution satellite sensors. The major scientific results were achieved during the definition and implementation of two scientific software, (SISAR and DATE) and other original methodologies. In SISAR both rigorous and Rational Polynomial Functions (RPFs) models are implemented, with a specific tool for the terrain-independent Rational Polynomial Coefficients (RPCs) generation; the software is scalable and it manages imagery acquired by several optical sensors and by COSMO-SkyMed, TerraSAR-X, RADARSAT-2 SAR sensors; in SISAR, it has been embedded an advanced patented matching method based on a coarse-to-fine hierarchical solution, with an effective combination of geometrical constrains and an Area Base Matching (ABM) algorithm. In DATE, which is a Free and Open Source Software (FOSS), an innovative and efficient strategy for DSMs generation has been implemented both for optical and SAR imagery, exploiting the new concept of Ground quasi-Epipolar Images (GrEI) for fast epipolar geometry achievement, and dense matching algorithms from computer vision. Original methodologies were defined and implemented: (1) to refine and regenerate terrain-independent Rational Polynomial Coefficients (RPCs) was defined and implemented in ENVI software; (2) for cloud processing of very big datasets of Landsat imagery, to estimate landcover change and land surface temperature variation. In 2009 GGD Image Analysis Group contributed to the Italian Guidelines for Orthoimages and Digital Terrain Models generation and validation, which were legally adopted in 2012 and are presently in force.
GGD is member since their foundation of the Copernicus Academy (EU Copernicus Program - 2016) and of the GNSS Raw Measurements Task Force (EU Global Navigation Satellite Systems Agency - 2017). Positioning and Image Analysis Groups have received more than 30 national and international awards; among them: DLR Special Topic Prize and Audience Award of the European Satellite Navigation Competition in 2010 (VADASE approach); Success Story of the European Satellite Navigation Competition in 2012 (VADASE approach, then implemented within Leica Geosystems AG GNSS receivers for permanent stations in 2015); ESA Certificate for Galileo In-Orbit-Validation in 2014; 10 Google Grants within Google Summer of Code in 2012 to 2016; one NASA Space Apps Challenge Global Award in 2016; one COSPAR Outstanding Paper Award in 2018; one AXA UNESCO PostDoc Fellowship; 3 Italian Scientists and Scholars of North American Foundation Internships; one URSI Young Scientist Award; 9 Italian Association of Professors in Geomatics (AUTeC) Best Ph.D. Thesis of the year, 2 Italian Remote Sensing Society (AIT) Eugenio Zilioli Award for MSc Theses.
At GGD, two patents, supported by Sapienza University of Rome, were developed in the frame of GNSS positioning and high resolution optical and SAR satellite imagery processing: 2010 Patent for VADASE (System for measuring coseismic movements or vibrations of structures based on global navigation satellite systems-gnss and/or pseudolites) (https://www.google.com/patents/EP2580607A1?cl=en&dq=en); 2013 Patent for Matching strategy for optical and SAR high resolution satellite imagery (Matching procedure and device for the digital modelling of objects by stereoscopic images) (https://www.google.com/patents/EP2772801A1?cl=en&hl=en).
