Geodaysit 2023

All archaeological sites are affected by changes due to a natural decay related to the ageing. If it compromises the functionality of the cultural property it becomes pathological and results in degradation. The monitoring, carried out with the use of innovative technologies, is a preliminary tool to an effective planned maintenance activity and therefore preventive conservation. Regarding these aspects the Parco archeologico del Colosseo took a strategic direction of a gradual transition from a plan of monitoring to a constant and planned conservation activity.
The monitoring project of the Parco archeologico del Colosseo (that started in a systematic way only in 2018) was inspired by the desire to build a sustainable system of protection and conservation, then allowing a proper tourism valorisation. With these objectives in mind, the Parco archeologico del Colosseo has developed a static and dynamic monitoring project consisting of five fundamental activities:
1. a database of all the historical data of the monuments, together with the existing graphic and photographic documentation (namely digital documen-tation archive);
2. visual monitoring carried out by teams of technicians dedicated to the inspection and control of monuments, also thanks to dedicated app that will allow to send data to the central system;
3. satellite monitoring (historical analysis of the satellite data) going directly into the system and analysed in order to monitor possible ground deformation;
4. in situ monitoring from traditional geotechnical instruments;
5. experimental activities.
Basically, the project involves the creation of a multi-parameter system of permanent control of the entire archaeological area, with the associated indicators of the level of risk, based on the combined use of innovative technologies.
In this way, the project will allow to plan, in an effective and timely manner, the necessary interventions for both ordinary and extraordinary maintenance, thus providing not only an operational tool, but also a management system for the Park with a better use of its financial resources.
As part of this monitoring project, the Parco del Colosseo requested the presence of experts from the Italian Space Agency (ASI).
The instrumental diagnostic tools are accompa-nied by satellite monitoring, already tested in the past for a short period, to obtain information on ground displacements, structures, and buildings. The use of satellite SAR interferometry technique applied to COSMO-SkyMed images is combined with the advantage of being able to use the archives of radar images that allow us to deduce, in an extensive manner, the evolution in time of more than twenty years of deformation processes. One of ASI's contributions to the monitoring project is to provide the images acquired by the COSMO-SkyMed satellites. Synthetic Aperture Radar (SAR) satellite data are gradually used for study applications and monitoring of cultural heritage, through multi-temporal analysis based on change detection techniques and differential interferometry (DInSAR). COSMO-SkyMed Constellation offers ideal features for routine monitoring of cultural heritage and observation in emergency situations which have been the subject of several demonstration, (pre-) operational and scientific research projects over the last sixteen years since the mission was declared fully operational. COSMO-SkyMed is the ASI SAR constellation, the only one in the world to be made up of 5 satellites operational (3 first generation and 2 second generation) in the X band, capable of providing very high spatial resolution images (up to 1m per civil use), very high acquisition frequency (revisit times up to 12 hours), in any meteorological and light conditions. The use of satellite SAR interferometry technique applied to COSMO-SkyMed images is combined with the advantage of being able to use the archives of radar images that allow us to deduce, in an extensive manner, the evolution in time of more than twenty years of deformation processes. For these reasons, the Parco also considered fundamental the satellite historical analysis of the archaeological area, carried out since 2010 until 2019. The satellite images, provided by ASI, were processed on commission by e-GEOS with interferometric technique. The data thus processed fed the web-GIS platform of the Parco’s monitoring project. (Della Giovampaola, 2021)

In the last 20 years, satellite technologies have been increasingly used for study, monitoring, conservation and promotion of cultural heritage, with a growing trend at both national and international levels. Recent publications critically reviewing the specialist scientific literature highlight a significant level of maturity of satellite applications in this domain (Luo et al., 2019; Tapete and Cigna, 2019a), so as satellite images collected from optical sensors have already become common data exploited by (geo-)archaeologists, researchers and heritage experts. At the same time, Synthetic Aperture Radar (SAR) technologies are increasingly being tested and exploited, also beyond the specialist image analyst community, thanks to multidisciplinary collaboration between different professionals (Tapete and Cigna, 2017) and facilitated SAR data access given the increasing provision by space agencies, also in “ready to use” formats (Tapete and Cigna, 2019b). At European level, the Italian ecosystem undoubtedly represents an excellence, given not only the long tradition in exploitation of innovative technologies for cultural heritage, but also the space sector investments into both Earth Observation missions with characteristics of image acquisition that well suit the user needs and requirements for this application domain, and initiatives promoting downstream applications and services development engaging small, medium and large enterprises. In continuity with the past decade, ASI continues launching and managing several initiatives for cultural heritage, in particular along the following directions:
• Undertaking scientific research and development, also through real-world user-driven use cases, e.g. demonstrating the performance achievable using national assets such as COSMOSkyMed data (Tapete and Cigna, 2019b; 2020);
• Supporting COSMO-SkyMed data exploitation in projects with Italian institutions (e.g. Ministry of Culture, Archaeological Park of Colosseum), and activities devoted to downstream applications and services development (e.g. in Pompeii, Capo Colonna) (Virelli et al., 2020);
• Promoting downstream by scientific, commercial and institutional users through the new programme “Innovation for Downstream Preparation” (I4DP), wherein safeguard of environment, cultural heritage and national landscape is among the key application domains.
The present paper therefore will illustrate ASI’s contribution for cultural heritage, alongside the current perspectives, in light of the COSMO-SkyMed programme (upstream) and “Multi-mission and Multi-Frequency SAR” and I4DP programmes (downstream), the latter with particular focus on the initiative dedicated to scientific users (I4DP_SCIENCE) according to the roadmap defined by Tapete & Coletta (2022).

References
Luo L., Wang X., Guo H., Lasaponara R., Zong X., Masini N., Wang G., Shi P., Khatteli H., Chen F. et al. (2019) Airborne and spaceborne remote sensing for archaeological and cultural heritage applications: A review of the century (1907–2017). Remote Sens. Environ., 232, 111280. doi: 10.1016/j.rse.2019.111280
Tapete D., Cigna F. (2017) Trends and perspectives of space-borne SAR remote sensing for archaeological landscape and cultural heritage applications. J. Archaeol. Sci. Reports, 14, 716–726. doi: 10.1016/j.jasrep.2016.07.017
Tapete D., Cigna F. (2019a) Detection of Archaeological Looting from Space: Methods, Achievements and Challenges. Remote Sens., 11, 2389. doi: 10.3390/rs11202389
Tapete D., Cigna, F. (2019b) COSMO-SkyMed SAR for detection and monitoring of archaeological
and cultural heritage sites. Remote Sens., 11, 1326. doi: 10.3390/rs11111326
Tapete D., Cigna F. (2020) Poorly known 2018 floods in Bosra UNESCO site and Sergiopolis in Syria
unveiled from space using Sentinel-1/2 and COSMO-SkyMed. Sci. Rep., 10, 12307. doi: 10.1038/s41598-020-69181-x
Tapete D., Coletta A. (2022) ASI’s roadmap towards scientific downstream applications of satellite
data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5643. doi: 10.5194/egusphere-egu22-5643, 2022.
Virelli et al. (2020) COSMO-SkyMed: uno strumento satellitare per il monitoraggio dei beni culturali. In: Monitoraggio e Manutenzione delle Aree Archeologiche. Cambiamenti climatici, dissesto idrogeologico, degrado chimico-ambientale / Atti del Convegno Internazionale di Studi, Roma, Curia Iulia, 20-21 Marzo 2019 / Alfonsina Russo e Irma Della Giovampaola - (a cura di) - «L’ERMA» di BRETSCHNEIDER, 2020 - (Collana Bibliotheca Archaeologica, 65) 278 p.; ill., pp. 103112.

Monitoring critical infrastructures and structures (energy and transportation) is one of the application domains of national relevance for which satellite technologies may be exploited to improve detection of causative factors of deterioration, mapping of sectors at risk, and prioritization of structural and maintenance works.
Although ground-based non-destructive testing (NDT) methods have been successfully applied for decades, reaching very high standards for data quality and accuracy, Synthetic Aperture Radar (SAR) satellite technology and interferometric techniques (InSAR) have proved to be a real “game changer”. The impact on infrastructure monitoring was particularly significant, also in light of the increased flow of SAR data collected in different radar bands and disseminated by space agencies in these past years.
ASI’s COSMO-SkyMed constellation operating in X-band is among the satellite assets that are mostly exploited by scientific and commercial community to perform high precision and accuracy monitoring, at high spatial and temporal resolution. Recent studies undertaken by ASI following “data exploitation” initiatives of COSMO-SkyMed data have highlighted an increasing use of these data to study and monitor bridges, motorways, railways, pipelines and plants. Scientific proof of concepts and demonstrators have led to strengthening national and international expertise in the use of InSAR multi-temporal techniques, and paved the way for downstream applications and mature monitoring services.
At the same time, the global scale availability of C-band Sentinel-1 data has contributed to a further dissemination of InSAR techniques for infrastructure monitoring, although the specialist literature has highlighted the limitations due to spatial resolution, as well as the need to combine different band SAR data collected at different resolution.
From 2021 to 2023, through the “Multi-mission and Multi-Frequency SAR” Program (Tapete et al., 2022), ASI has supported R&D projects focusing on data fusion and post-processing techniques in the field of infrastructure deformation monitoring. Benefits achievable through integration of multi-band SAR data (including L-band SAOCOM) have been demonstrated.
In light of these investments and the maturity of SAR data processing algorithms for generation of application products, ASI continues their institutional mission according to the following activities:
• In the upstream sector of satellite missions, improving SAR sensors to achieve new observation capabilities with COSMO-SkyMed Second Generation (CSG) satellites and facilitating the accessibility to long time series ensuring observation continuity;
• In the downstream sector of applications and services development, promoting SAR data exploitation, also in combination with navigation and telecommunications technologies, through the new programme “Innovation for Downstream Preparation” (I4DP), wherein management and monitoring of structural stability of critical infrastructures is among the application domains of recent funding and projects initiation.
The present paper therefore will illustrate ASI’s contribution on this application domain, alongside the current perspectives, in light of the COSMO-SkyMed programme (upstream) and “Multi-mission and Multi-Frequency SAR” and I4DP programmes (downstream), the latter with particular focus on the initiative dedicated to scientific users (I4DP_SCIENCE).

References
Tapete et al. (2022) ASI's “Multi-mission and Multi-Frequency SAR” Program for Algorithms Development and SAR Data Integration Towards Scientific Downstream Applications. IGARSS 2022, pp. 4498-4501, doi: 10.1109/IGARSS46834.2022.9884937.