Through the massive processing of more that 2700 SAR scenes, we prepared a total of 42 deformation maps, deformation velocity maps, and associated time series for 13 test sites, delivering more than 30-million point-scatters on the ground, with an average density of 830 points per km2. This is an unprecedented result for a project of this class. By itself, this is a significant result of the DORIS project.
In the following, the main highlights of DORIS are described. The description focuses on the technological, methodological and scientific impact of the results obtained.
The first highlight consists in the production of very-long time series of ground deformation & associated maps obtained processing the unique archives of the ESA ERS-1/2 & ENVISAT SAR data. For the purpose, partners have developed specific, innovative Persistent Scatter Interferometry (PSI) techniques.
A second highlight consists in the detection of very fast-moving, non-linear deformation patterns caused e.g., by active mining, and by seasonal movements of rock glaciers and the melting of permafrost in mountain areas.
A third highlight consists in the extensive use of the high spatial and temporal resolution X-band data for the detection and mapping of deformations in urban and sub-urban areas with unprecedented spatial detail.
A fourth highlight consists in multi-frequency analysis i.e., joint analysis of the results of the processing of SAR data captured by multiple sensors for the same area. Multi-frequency analysis was possible because of the availability of multi-band datasets for several of the DORIS test sites.
A fifth highlight of DORIS consists in the development of methodologies to improve the exploitation of multi-sensor DInSAR techniques for landslides and subsidence mapping and monitoring. The scope of the methodologies is to generate landslide and subsidence activity maps, combining remote sensing and in situ (ground truth) data.
A significant highlight of DORIS is the extensive exploitation of terrestrial, or Ground Based Radar Interferometry. Ground Based Radar Interferometry (GBRI) exploits images captured by terrestrial radars. Both interferometers and synthetic aperture radar (SAR) systems are used. The area covered by a GBRI system depends largely on the distance from the location of the instrument (i.e., the observation point).
A particularly important highlight of DORIS is the synergic exploitation of advanced DInSAR-derived products, with in situ and thematic data and information, for improved analysis and modelling of landslides and subsidence phenomena. DORIS experimented multiple integrated analyses of DInSAR-derived products and in situ and thematic information. In this section, three particularly relevant examples are presented and discussed.
A last highlight of DORIS consists in the modification of the original Multiple Change Detection (MCD) technique for the detection and mapping of event-triggered landslides using VHR images captured by optical (multi-spectral) satellite sensors.