GI5.3

Ground Penetrating Radar: Applications and Advancements

The never-ending growth of the ground penetrating radar applications reserves continuously small and less small discoveries, and deserves a space for discussion and reciprocal listening also at the EGU conference.
The pandemic has meaningfully hindered many activities but to our knowledge not too much the interest in the GPR instrumentation and technique at an applicative level, even if exchanges of experiences at international conferences have been of course necessarily reduced. So, we hope that this session can meet the interest of many researchers, professionals, PhD students as well skilled GPR users as geologists, engineers, geophysicists and possibly archaeologists and architects.
Contributions are welcome with regard to all the aspects of the GPR technique, ranging from the hardware of the systems to the data processing and any theoretical aspect, including innovative applications or procedures as well as results of particular relevance, possibly achieved within an integrated measurement campaign including also different data.
Hope to see you in Vienna.

Co-organized by EMRP2/NH6/SSP3
Convener: Raffaele Persico | Co-conveners: Alessandro Fedeli, Marco Salucci, Salvatore Piro, Michele Ambrosanio
Presentations
| Mon, 23 May, 10:20–11:38 (CEST)
 
Room 0.51

Presentations: Mon, 23 May | Room 0.51

10:20–10:26
|
EGU22-795
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ECS
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On-site presentation
Triven Koganti, Ellen Van De Vijver, Barry J. Allred, Mogens H. Greve, Jørgen Ringgaard, and Bo V. Iversen

Agricultural subsurface drainage systems are installed in naturally poorly drained soils and areas with a rising water table to drain the excess water, eradicate soil salinization issues and increase crop yields. Globally, some of the most productive regions are a result of these artificial drainage practices. The installation of drainage systems provides many agronomic, economic, and environmental benefits. However, inevitably, they act as shortened pathways for the transport of undesired substances (nutrients, pesticides, and pathogens) through the soil profile promoting their increased leaching and offsite release to the surface water bodies. This drainage water cause potential eutrophication risk to the aquatic ecosystem. For example, the hypoxic zone in the Gulf of Mexico and harmful algal blooms in Lake Erie can be linked to the nitrogen and phosphorus losses from the Midwest USA agricultural areas. Hence, the knowledge of the location of these installations is essential for hydrological modelling and to plan effective edge-of-field mitigation strategies such as constructed wetlands, saturated buffer zones, denitrifying bioreactors, and phosphate filters. Moreover, their location is also important either in order to initiate repairs or retrofit a new drainage system to the existing one. Nevertheless, subsurface drainage installations are often poorly documented and this information is inaccurate or unavailable, inducing the need for extensive mapping campaigns. The conventional methods for drainage mapping involve tile probing and trenching equipment. While the use of tile probes provide only localized and discrete measurements, employing trenching with heavy machinery can be exceedingly invasive and carry a risk of severing the drainage pipes necessitating costly repairs. Non-destructive soil and crop sensors might provide a rapid and effective alternative solution. Previous studies show ground penetrating radar (GPR) to be especially successful; owing to its superior resolution over other near-surface geophysical methods. In this study, we tested the use of a stepped-frequency continuous wave (SFCW) 3D-GPR (GeoScope Mk IV 3D-Radar with DXG1820 antenna array) at study sites in Denmark and a time-domain GPR (Noggin 250 MHz SmartCart) at study sites in the Midwest USA to map the buried drainage pipes. The 3D-GPR mounted in a motorized survey configuration and mobilized behind an all-terrain vehicle proved certainly advantageous to get full coverage of the farm field area and provided the flexibility of adjusting the frequency bandwidth depending on the desired resolution and penetration depth (PD). Two different approaches were tested to estimate the PD and comparisons were made with electrical conductivity data measured using an electromagnetic induction instrument. With the impulse GPR, data collected along limited parallel transects spaced a few meters apart, spiral and serpentine segments incorporated into random survey lines proved sufficient when used adjacently with unmanned aerial vehicle imagery. In general, a better success can be expected when the average soil electrical conductivity is less than 20 mS m-1 and it is a recommendation to perform the GPR surveys preferably in a direction perpendicular to the expected drain line orientation when the water table is at/below the drainage pipes’ depth.

How to cite: Koganti, T., Van De Vijver, E., J. Allred, B., H. Greve, M., Ringgaard, J., and V. Iversen, B.: Mapping of Agricultural Subsurface Drainage Systems Using Time and Frequency Domain Ground Penetrating Radars, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-795, https://doi.org/10.5194/egusphere-egu22-795, 2022.

10:26–10:32
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EGU22-948
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ECS
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On-site presentation
M.Reza Ershadi, Reinhard Drews, Inka Koch, Jonathan Hawkins, Keith Nicholls, Joshua Elliott, Falk Oraschewski, Richard Hanten, Cornelia Schulz, Sepp Kipfstuhl, and Olaf Eisen

Acquisition of quad-polarimetric radar data on ice sheets gives insights about the ice-fabric variability with depth and consequently can deliver essential constraints on the spatially variable ice rheology. Polarimetric measurements are collected manually in most ground-based surveys, discretely sampling a limited profile range. Measurements are time-intensive and often do not cover critical areas such as shear zones where field safety is a concern. Autonomous rovers can provide an alternative that optimizes for time, sampling resolution and safety.  

Here, we present an autonomous acquisition technique of quad-polarimetric radar data using a rover. This technique is based on a previous layout that has proven its capacity to navigate in various snow conditions but did not yet actively trigger the geophysical instruments attached. We upgraded the rover with a novel Robotic Operating System (ROS2) that interfaces simultaneously with a real-time positioning GPS and an automatic phase-sensitive radio-echo sounder (ApRES) with multiple transmitters multiple receivers. Like this, the rover can autonomously steer to pre-destined waypoints and then take static measurements at those locations also in areas where field safety might be compromised. We demonstrate this proof-of-concept on the Ekström Ice Shelf Antarctica, where we acquired densely spaced polarimetric radar data measurements. The rover’s operating system offers many opportunities for other measurement principles, e.g., densely spaced co-polarized data suitable for synthetic aperture radar (SAR) processing.

How to cite: Ershadi, M. R., Drews, R., Koch, I., Hawkins, J., Nicholls, K., Elliott, J., Oraschewski, F., Hanten, R., Schulz, C., Kipfstuhl, S., and Eisen, O.: Quad-polarimetric radar measurements autonomously obtained with an ice-rover at Ekström Ice Shelf, East Antarctica, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-948, https://doi.org/10.5194/egusphere-egu22-948, 2022.

10:32–10:38
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EGU22-1144
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Virtual presentation
José A. Peláez, Juan L. Soler, Rashad Sawires, Alejandro Jiménez, and José M. Alba

The necropolis of Qubbet el-Hawa is located in West-Aswan, Upper Egypt. It looks like a huge dune covering the massive Nubian Sandstone Group, hosting one of the most densely occupied cemeteries of Ancient Egypt, dating back to c. 2500 B.C. to the Roman Period. Here we present the used methodology and the conducted ground-penetrating radar (GPR) survey accomplished in the Qubbet El-Hawa site.

Three different geological formations have been differentiated in the studied area. From bottom to top, the Abu Agag, the Timsah and the Um Barmil formations, which mainly belong to the Nubian Sandstone Group. The conducted GPR survey was accomplished in the Timsah Formation, the most heterogeneous formation of all of them, in which along its outcrops can be observed several stratigraphic discontinuities, being usually the alternation of lutite (mainly claystone), sandstone, and iron oxides, arranged in alternating layers varied in thickness from 5 to 10 cm, and from 30 to 50 cm thick blocks.

The studied area, 20 m width × 45 m length, showing a near-constant slope of about 35°, was surveyed using 250 and 500 MHz shielded antennas in a dense array pattern. Although dry eolian sand and sandstone rocks do not display a clear difference in their electromagnetic characteristics, the conducted survey was able to discriminate/define the interface among the underlying sandstone and the sand cover. This good behavior could be attributed to the different overlapping layers including ferruginous sediments and claystone. This was possible even when the studied area exhibits a steep slope, as well as many loose rocks in some parts, coming from the outcrops, that made the measurement difficult to carry out in some cases.

The interface among the underlying sandstone formation and the sand cover is acceptably resolved, providing some very useful data to archaeologists about the near-surface shape of the bedrock and their possible willingness to host some graves.

How to cite: Peláez, J. A., Soler, J. L., Sawires, R., Jiménez, A., and Alba, J. M.: Ground Penetrating Radar survey at the archaeological site of Qubbet El-Hawa, Aswan, Egypt, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1144, https://doi.org/10.5194/egusphere-egu22-1144, 2022.

10:38–10:44
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EGU22-1785
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ECS
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On-site presentation
Emanuele Colica, Sebastiano D'Amico, Giorgio Rizzo, and Raffaele Persico

We will present the results of Ground Penetrating Radar ([1-3] and passive seismic [4] prospections performed in the villa of Madonna dell’Alto in Campi Salentina (in the outskirts of Lecce, southern Italy). The structure dates back to the nineteen’s century.  The villa presents a peculiar structure having a central room of a hexagonal shape surrounded by several other small rooms.  GPR prospecting has been performed in a central hexagonal room acquiring data on an orthogonal grid having a spacing of 25 cm. The GPR system used was a Ris Hi-Mode manufactured by IDSGeoradar s.r.l. and equipped with a dual antenna at central frequency 200 and 600 MHz.  A classical processing composed of zero timing, background removal, gain vs. depth. 1D filtering, Kirchhoff migration and depth slicing was applied on the data. The propagation velocity exploited for the migration algorithm was c=12 cm/ns. In this area, from the slices, we have noted an apparent target at the time depth of 390 cm. However, a comparison with the Bscans revealed that it is most probably due to the effects of the walls and the ceiling of the room where the measurements were taken. Single GPR lines were also taken in the other rooms of the villa where some potential anomalies have been identified. However, another campaign is planned in order to extend the data collection and interpretation.

Furthermore, within the Villa a set of seismic passive measurements have been taken by the means of a portable seismograph. The data where acquired both inside the structure in correspondence of the GPR investigation as well as on top of the structure. Data were processed by applying the H/V and the H/H [4] techniques.

Acknowledgements

This study was supported by a STSM Grant from COST Action SAGA: The Soil Science & Archaeo-Geophysics Alliance - CA17131 (www.saga-cost.eu), supported by COST (European Cooperation in Science and Technology www.cost.eu). We are also grateful to the Institute for the Electromagnetic Sensing of the Environment IREA-CNR, which put at our disposal the system with which the GPR measurements were taken.

References

[1] G. Gennarelli, I. Catapano, F. Soldovieri, R. Persico, On the Achievable Imaging Performance in Full 3-D Linear Inverse Scattering, IEEE Trans. on Antennas and Propagation,  vol. 63, n. 3, pp. 1150-1155, March 2015.

[2] F. Gabellone, G. Leucci, N. Masini, R. Persico, G. Quarta, F. Grasso, “Nondestructive Prospecting and virtual reconstruction of the chapel of the Holy Spirit in Lecce, Italy”, Near Surface Geophysics, vol. 11, n. 2, pp. 231-238, April 2013.

[3] E. Colica, A. Antonazzo, R. Auriemma, L. Coluccia, I. Catapano, G. Ludeno, S. d’Amico, R. Persico, GPR investigation at the archaeological site of Le Cesine, Lecce, Italy, Information Science Vol. 12 n. 10, 412, https://doi.org/10.3390/info12100412, 2021.

[4] Panzera F., D'Amico S., Lombardo G., Longo E., 2016. Evaluation of building fundamental periods and effects of local geology on ground motion parameters in the Siracusa area, Italy. Journal of Seismology, 20, 1001-1019, doi:10.1007/s10950-016-9577-5

How to cite: Colica, E., D'Amico, S., Rizzo, G., and Persico, R.: Ground Penetrating Radar and passive seismic investigation at the villa of Madonna dell’Alto in Campi Salentina (Lecce, Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1785, https://doi.org/10.5194/egusphere-egu22-1785, 2022.

10:44–10:50
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EGU22-2481
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Virtual presentation
Salvatore Piro and Daniele Verrecchia

The Monte Abatone Project, jointly developed between the Campania University “Luigi Vanvitelli” (Caserta) Prof. F. Gilotta, the Tuscia University (Viterbo) Prof. M. Micozzi and A. Coen, the Bonn University, Prof. M. Bentz and ISPC (CNR) is based on the development of an integrated research employing different methodologies to reconstruct the limits of the necropolis and the location of all different tombs. This necropolis is one of the main important necropolis of Cerveteri, located 60 km north of Rome (Latium, Italy). In the period 1950-1960, several tombs have been discovered and excavated, though still many remain hidden underneath the subsurface. In the period between 2018 - 2021, geophysical surveys have been carried out to investigate the unexplored portions of the ancient Etruscan Necropolis, to provide a complete mapping of the position of the tombs. Ground Penetrating Radar and the Magnetometric methods have been systematically employed to investigate about twelve hectares of the necropolis. GPR system SIR 3000 (GSSI), equipped with a 400 MHz antenna with constant offset, SIR4000 (GSSI) equipped with a dual frequency antenna with 300/800 MHz and the 3D Radar Geoscope multichannel stepped frequency system were employed to survey the selected areas where the presence of tombs was hypothesized from previous archaeological studies.

All the GPR profiles were processed with GPR-SLICE v7.0 Ground Penetrating Radar Imaging Software (Goodman 2020). The basic radargram signal processing steps included: post processing pulse regaining; DC drift removal; data resampling; band pass filtering; background filter and migration. With the aim of obtaining a planimetric vision of all possible anomalous bodies, the time-slice representation was calculated using all processed profiles showing anomalous sources up to a depth of about 2.5 m. The obtained results clearly show the presence of a network of strong circular or rectangular features, linked with the buried structural elements of the searched chamber or pit tombs. Together with archaeologists, these anomalies have been interpreted to have a good matching with the expected searched tombs. The obtained results have enhanced the knowledge of the necropolis layout and mapping. After the geophysical surveys, direct excavations have been conducted, which brought to light few of the investigated structures. The obtained results, after the excavation, have been compared and integrated with the geophysical maps to define the keys for the interpretation.

References

Campana S., Piro S., 2009. Seeing the Unseen. Geophysics and Landscape Archaeology. Campana & Piro Editors. CRC Press, Taylor & Francis Group. Oxon UK, ISBN 978-0-415-44721-8.

Goodman, D., Piro, S., 2013. GPR Remote sensing in Archaeology, Springer: Berlin.

Piro S., Papale E., Zamuner D., Kuculdemirci M., 2018. Multimethodological approach to investigate urban and suburban archaeological sites. In “Innovation in Near Surface Geophysics. Instrumentation, application and data processing methods.”, Persico R., Piro S., Linford N., Ed.s. pp. 461 – 504, ISBN: 978-0-12-812429-1, pp.1-505, Elsevier.

How to cite: Piro, S. and Verrecchia, D.: New integrated GPR surveys, using different frequencies, with direct archaeological excavations to locate chamber tombs in Monte Abatone necropolis, Cerveteri (Italy)., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2481, https://doi.org/10.5194/egusphere-egu22-2481, 2022.

10:50–10:56
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EGU22-2509
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Presentation form not yet defined
Ilaria Catapano, Giovanni Ludeno, Emanuele Colica, Sebastiano D’Amico, Antonella Antonazzo, Rita Auriemma, Luigi Coluccia, and Raffaele Persico

This contribution deals with a GPR prospecting performed in the archaeological site of Le Cesine, Lecce, Southern Italy [1]. The measurement campaign was performed in the framework of a short-term scientific mission (STSM) funded by the European Cost Action 17131 (acronym SAGA), and aimed to map the subsoil of three wide areas in order to address and rationalize future archaeological excavations. As an innovative aspect, beyond a traditional data processing [2], each one of the collected B-scans was processed by means of an innovative data processing, which is based on an inverse scattering algorithm [3-4] accompanied by a shifting zoom procedure [5]. This latter makes possible a computationally effective microwave imaging of electrically large spatial domains and imitates, in a suitable way, the truncation applied on the migration integral, theoretically extended on an infinite observation line but practically necessarily limited to a finite line. For each investigated area, the B-scans, as elaborated by means of the innovative data processing procedure, were combined in order to obtain a depth slice visualization of the investigated areas. As it will be shown at the conference, the obtained images revealed the presence of buried ruins, maybe ascribable to structures related to an ancient Roman harbour. These results motivated founding request for archaeological excavations, which hopefully will be possible to execute in the next few years, and will confirm or correct the hypotheses suggested by the GPR survey as enhanced by the innovative data processing.

 

Acknowledgements

This study was supported by a STSM Grant from COST Action SAGA: The Soil Science & Archaeo-Geophysics Alliance - CA17131 (www.saga-cost.eu), supported by COST (European Cooperation in Science and Technology www.cost.eu).

References

[1] E. Colica, A. Antonazzo, R. Auriemma, L. Coluccia, I. Catapano, G. Ludeno, S. d’Amico, R. Persico, GPR investigation at the archaeological site of Le Cesine, Lecce, Italy, Information Science Vol. 12 n. 10, 412, https://doi.org/10.3390/info12100412, 2021.

[2] F. Gabellone, G. Leucci, N. Masini, R. Persico, G. Quarta, F. Grasso, “Nondestructive Prospecting and virtual reconstruction of the chapel of the Holy Spirit in Lecce, Italy”, Near Surface Geophysics, vol. 11, n. 2, pp. 231-238, April 2013.

[3] I. Catapano, G. Gennarelli, G. Ludeno and F. Soldovieri, "Applying Ground-Penetrating Radar and Microwave Tomography Data Processing in Cultural Heritage: State of the Art and Future Trends," in IEEE Signal Processing Magazine, vol. 36, no. 4, pp. 53-61, July 2019,.

[4] G. Gennarelli, I. Catapano, F. Soldovieri, R. Persico, On the Achievable Imaging Performance in Full 3-D Linear Inverse Scattering, IEEE Trans. on Antennas and Propagation,  vol. 63, n. 3, pp. 1150-1155, March 2015.

[5] R. Persico, G. Ludeno, F. Soldovieri, A. De Coster, S. Lambot, 2D linear inversion of GPR data with a shifting zoom along the observation line, Remote Sensing, 9, 980; doi: 10.3390/rs9100980, open access, 2017.

How to cite: Catapano, I., Ludeno, G., Colica, E., D’Amico, S., Antonazzo, A., Auriemma, R., Coluccia, L., and Persico, R.: An innovative processing applied to GPR data gathered in the archaeological site of Le Cesine, Lecce, Italy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2509, https://doi.org/10.5194/egusphere-egu22-2509, 2022.

10:56–11:02
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EGU22-3152
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Presentation form not yet defined
Raffaele Persico, Grazia Semeraro, Corrado Notario, and Ilaria Catapano

In this abstract we propose the results of GPR measurements [1-2] performed in a site of cultural interest. In particular, the measurements were performed in a rectangular area inside the Messapic archaeological ancient settlement of Cavallino, close to Lecce (southern Italy) with a RIS-Hi model GPR system manufactured by IDSGeoradar s.r.l. and belonging to the Institute for the Electromagnetic Sensing of the Environment IREA-CNR. The data processing was performed according to a classical sequence of steps provided by zero timing, background removal, gain vs. depth, 1D filtering and time domain migration [3]. Afterwards, slicing was performed too and the results were georeferenced in QGIS thanks to the coordinatives of the four vertex of the rectangular area. The results indicate that there are some possible Messapic remains in the investigated area and suggest somehow the most promising point for a future localized excavation.  Future development will regard further processing of the data with an inverse scattering [4] algorithm accompanied with a shifting zoom procedure, that will make it possible to apply the inverse scattering approach to an electrically large domain [5].

 

Acknowledgments

This work is supported by the project AMOR – Advanced Multimedia and Observation services for 
the Rome cultural heritage ecosystem, financed within the call ESA 5G for L’ART (Business Applications programme).

References

[1] F. Gabellone, G. Leucci, N. Masini, R. Persico, G. Quarta, F. Grasso, “Nondestructive Prospecting and virtual reconstruction of the chapel of the Holy Spirit in Lecce, Italy”, Near Surface Geophysics, vol. 11, n. 2, pp. 231-238, April 2013.

[2] R. Persico, S. D'Amico, L. Matera, E. Colica, C. De, Giorgio, A. Alescio, C. Sammut and P. Galea, GPR Investigations at St John's Co‐Cathedral in Valletta. Near Surface Geophysics, vol. 17 n. 3, pp. 213-229. doi:10.1002/nsg.12046, 2019.

[3] G. Gennarelli, I. Catapano, F. Soldovieri, R. Persico, On the Achievable Imaging Performance in Full 3-D Linear Inverse Scattering, IEEE Trans. on Antennas and Propagation,  vol. 63, n. 3, pp. 1150-1155, March 2015.

[4] I. Catapano, G. Gennarelli, G. Ludeno and F. Soldovieri, "Applying Ground-Penetrating Radar and Microwave Tomography Data Processing in Cultural Heritage: State of the Art and Future Trends," in IEEE Signal Processing Magazine, vol. 36, no. 4, pp. 53-61, July 2019,.

[5] R. Persico, G. Ludeno, F. Soldovieri, A. De Coster, S. Lambot, 2D linear inversion of GPR data with a shifting zoom along the observation line, Remote Sensing, 9, 980; doi: 10.3390/rs9100980, open access, 2017.


 

How to cite: Persico, R., Semeraro, G., Notario, C., and Catapano, I.: GPR prospecting in the archaeological site of Cavallino, Lecce, Italy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3152, https://doi.org/10.5194/egusphere-egu22-3152, 2022.

11:02–11:08
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EGU22-5163
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ECS
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Virtual presentation
Michele Ambrosanio, Stefano Franceschini, Maria Maddalena Autorino, and Vito Pascazio

Subsurface and underground exploration and monitoring are of interest for several applications which span from geoscience and archaeology to security and safety areas [1, 2]. In the framework of non-destructive testing, ground penetrating radar (GPR) represents a valuable technology that has been extensively exploited for the detection and characterization of buried objects. Nevertheless, this remote sensing modality has some limitations related to the generated output, since these images of the underground require an expert user for their interpretation. Moreover, identifying and characterizing buried objects still represent a non-trivial task [3].

To this aim, several algorithms have been developed to face the aforementioned issues efficiently and automatically. In this context, approaches based on deep learning and convolutional neural networks (CNNs) have been proposed in the past years and recently gained a lot of attention by the scientific community [4]. Despite their efficiency, these approaches require many cases to perform the training step and improve their classification performance.

In this abstract, the case of a multistatic GPR system is considered via two-dimensional numerical simulations to classify the kind of underground utility automatically in areas in which both water and natural gas pipes can be located. More in detail, some discussions on the classification performance by adopting different topologies and network architectures will be dealt with.

 

[1] Persico, R., 2014. Introduction to ground penetrating radar: inverse scattering and data processing. John Wiley & Sons.

[2] Catapano, I., Gennarelli, G., Ludeno, G. and Soldovieri, F., 2019. Applying ground-penetrating radar and microwave tomography data processing in cultural heritage: State of the art and future trends. IEEE Signal Processing Magazine, 36(4), pp.53-61.

[3] Ambrosanio, M., Bevacqua, M.T., Isernia, T. and Pascazio, V., 2020. Performance Analysis of Tomographic Methods Against Experimental Contactless Multistatic Ground Penetrating Radar. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 14, pp.1171-1183.

[4] Kim, N., Kim, S., An, Y.K. and Lee, J.J., 2019. Triplanar imaging of 3-D GPR data for deep-learning-based underground object detection. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 12(11), pp.4446-4456.

How to cite: Ambrosanio, M., Franceschini, S., Autorino, M. M., and Pascazio, V.: Deep Learning Strategies for Target Classification via Tomographic Ground Penetrating Radar, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5163, https://doi.org/10.5194/egusphere-egu22-5163, 2022.

11:08–11:14
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EGU22-5568
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Virtual presentation
Cristina Ponti, Andrea Randazzo, Alessandro Fedeli, Matteo Pastorino, and Giuseppe Schettini

The use of Ground Penetrating Radar (GPR) as a non-destructive technique for the localization and imaging of buried targets is nowadays widely used in the fields of civil engineering, archeology, and geology. In traditional GPR applications, the transmitting antenna is placed in air, whereas targets are embedded in a background of different permittivity, which may be given by a soil or a construction material. However, the GPR architecture can be also applied to the case of targets located in air but hidden from the illumination field radiated by the transmitting antenna by a dielectric discontinuity, as in the case of the Through-the-Wall (TW) radar applications, where targets inside a building interior must be localized and imaged [1]. In this work, a commercial GPR equipment is employed to perform an experimental campaign on a TW scene, where two targets of different reflectivity, i.e., a metallic cylinder and a wooden bar, are located behind a masonry wall in a laboratory environment. To increase the information on the scattered fields, the scanning of the transmitting and receiving antennas is performed in a fully multi-bistatic manner, through a multi-view and multi-illumination mode, along a horizontal line parallel to the wall, and keeping the antennas in direct contact with it. The transmitting antenna is a transducer emitting a pulsed signal, with frequency centered at 1 GHz. The imaging of the buried targets has been performed through a novel two-step inverse-scattering technique, that is based on a regularization scheme developed in the framework of variable exponent Lebesgue spaces [2], [3]. In particular, the norm exponent function is directly built from the available data through an initial processing of the data, based on a beamforming approach or on a truncated singular value decomposition (TSVD) technique [4]. The whole frequency spectrum of the measured data is exploited, as the scattered field from the pulsed signals is extracted on a set of frequencies through a Fast Fourier Transform. The proposed approach, applied to the measured data, shows good reconstruction capabilities and a reduction of artifacts.

 

[1] M. G. Amin, Ed., Through-the-Wall Radar Imaging. Boca Raton, FL: CRC Press, 2011.

[2] C. Estatico, A. Fedeli, M. Pastorino, and A. Randazzo, ‘Quantitative microwave imaging method in Lebesgue spaces with nonconstant exponents’, IEEE Trans. Antennas Propag., vol. 66, no. 12, pp. 7282–7294, Dec. 2018.

[3] A. Randazzo, C. Ponti A. Fedeli, C. Estatico, P. D’Atanasio, M. Pastorino, G. Schettini, ‘A two-step inverse-scattering technique in variable-exponent Lebesgue spaces for through-the-wall microwave imaging: Experimental results’, IEEE Trans. Geosci. Remote Sens., vol. 59, no. 9, pp. 7189–7200, Sep. 2021.

[4] A. Randazzo, C. Ponti, A. Fedeli, C. Estatico, P. D’Atanasio, M. Pastorino, G. Schettini, ‘A Through-the-Wall Imaging Approach Based on a TSVD/Variable-Exponent Lebesgue-Space Method’, Remote Sens., vol. 13, 17 pp., 2021.

How to cite: Ponti, C., Randazzo, A., Fedeli, A., Pastorino, M., and Schettini, G.: Multi-illumination and multi-view GPR measurements for Through-the-Wall radar imaging, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5568, https://doi.org/10.5194/egusphere-egu22-5568, 2022.

11:14–11:20
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EGU22-5813
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ECS
|
Virtual presentation
Francesco Zardi, Lorenzo Poli, and Andrea Massa

Ground Penetrating Radar (GPR) is a technology of high interest due to its many applications [1], requiring to process the collected data to retrieve the shape and/or electromagnetic (EM) characteristics of the imaged objects. Such a task can be formulated as an Inverse Scattering Problem (ISP), whose solution poses paramount challenges due to the ill-posedness and non-linearity [1]. Therefore, "smart" solution approaches must be developed capable of fully exploiting the available/acquired information to achieve satisfying reconstructions with limited computational resources. In this framework, the development of innovative GPR imaging methodologies is an active research area of the ELEDIA Research Center at the University of Trento, Italy. GPR microwave imaging strategies based on the Multiresolution (MR) paradigm demonstrated significant improvements in terms of reconstruction accuracy and inversion time [2]-[5]. The strength of the MR framework stems from balancing the number of unknowns with the amount of available data, reducing the non-linearity of the ISP. Moreover, it allows a straightforward exploitation of the "progressively-acquired" information on the imaged domain, resulting in a mitigation of the ill-posedness. Effective MR strategies have been recently proposed based on the exploitation of stochastic optimization algorithms [4] to mitigate the risk of false solutions. Recently, an MR-based solution strategy has been proposed that exploits an Inexact Newton method developed in Lp spaces to achieve better regularization of the subsurface ISP thanks to the joint processing of multiple spectral components of GPR data [5]. Another solution paradigm significantly improving the performance of GPR data inversion is the System-by-Design (SbD) [6][7]. The SbD, defined as "a framework to deal with complexity" in EM problems [6] leverages on the recent advancements in the area of Learning-by-Examples techniques and it allows a proper reformulation of the ISP enabling the "smart" reduction of its unknowns and the definition of a fast surrogate model to markedly reduce the computational burden of multi-agent evolutionary-inspired optimization tools [6][7]. 

References

[1] R. Persico, Introduction to Ground Penetrating Radar: Inverse Scattering and Data Processing. Hoboken, New Jersey: Wiley, 2014.
[2] M. Salucci et al. “GPR prospecting through an inverse-scattering frequency-hopping multifocusing approach,” IEEE Trans. Geosci. Remote Sens., vol. 53, no. 12, pp. 6573-6592, Dec. 2015.
[3] M. Salucci et al., “Advanced multi-frequency GPR data processing for non-linear deterministic imaging,” Signal Process., vol. 132, pp. 306–318, Mar. 2017.
[4] M. Salucci et al., “Multifrequency particle swarm optimization for enhanced multiresolution GPR microwave imaging,” IEEE Trans. Geosci. Remote Sens., vol. 55, no. 3, pp. 1305-1317, Mar. 2017.
[5] M. Salucci et al., “2-D TM GPR imaging through a multiscaling multifrequency approach in Lp spaces,” IEEE Trans. Geosci. Remote Sens., vol. 59, no. 12, pp. 10011-10021, Dec. 2021.
[6] A. Massa and M. Salucci, “On the design of complex EM devices and systems through the System-by-Design paradigm - A framework for dealing with the computational complexity,” IEEE Trans. Antennas Propag., in press (DOI: 10.1109/TAP.2021.3111417).
[7] M. Salucci et al., "Learned global optimization for inverse scattering problems - Matching global search with computational efficiency," IEEE Trans. Antennas Propag., in press (DOI: 10.1109/TAP.2021.3139627).

How to cite: Zardi, F., Poli, L., and Massa, A.: From Multiresolution to the System-by-Design based GPR Imaging, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5813, https://doi.org/10.5194/egusphere-egu22-5813, 2022.

11:20–11:26
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EGU22-7170
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Virtual presentation
James Irving, Chongmin Zhang, Mathieu Gravey, and Grégoire Mariéthoz

A common challenge in the processing and analysis of ground-penetrating radar (GPR) reflection data is the reconstruction of missing traces. Gap filling, for example, may be required where data could not be recorded in the field in order to reduce artifacts produced during migration. Similarly, proper visualization and imaging of a GPR profile requires an even trace spacing, meaning that trace regularization is typically needed when the data are acquired in continuous mode using a fixed trace acquisition rate. Lastly, we may wish to increase the spatial resolution of a GPR dataset through trace densification, whereby new traces are reconstructed between existing ones, in order to improve data interpretability. 

A number of methods have been proposed for the reconstruction of missing GPR data over the past few decades, which vary in their degree of complexity and underlying assumptions. Simple strategies such as linear, cubic, and sinc interpolation can be highly effective, but only in the absence of spatial aliasing. When aliasing is present, other methods that exploit the predictability and/or sparseness of the GPR data, commonly in a transformed domain, may be utilized. However, such methods often involve overly simplistic assumptions about the data structure (e.g., that windowed portions of data can be described by sum of plane waves), which can lead to unrealistic and linear results as gaps in the data become large. Finally, all current reconstruction approaches lead to a single "best" estimate of the missing traces based on the existing measurements and some explicit or implicit choice of prior information, with no consideration of the corresponding uncertainty.

Here, we attempt to address these shortcomings by considering a GPR data reconstruction strategy based on the QuickSampling (QS) multiple-point geostatistical method. With this approach, GPR traces are simulated via sequential conditional simulation based on patterns that are observed in nearby high-resolution data (training images). To demonstrate the potential of this approach, we show its successful application to a variety of examples involving gap filling, regularization, and trace densification.

How to cite: Irving, J., Zhang, C., Gravey, M., and Mariéthoz, G.: Reconstruction of GPR data using multiple-point geostatistics, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7170, https://doi.org/10.5194/egusphere-egu22-7170, 2022.

11:26–11:32
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EGU22-8022
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ECS
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Virtual presentation
Alessandro Fedeli, Valentina Schenone, Matteo Pastorino, and Andrea Randazzo

Ground penetrating radar (GPR) prospection of underground scenarios is proven useful in numerous fields, from geophysics to structural engineering. At present, most of the typically deployed approaches make use of qualitative processing of GPR data [1]. Nevertheless, despite their increased complexity, full-waveform inversion (FWI) methods are emerging as a key tool to provide a complete characterization of the buried region under test [2].

This contribution aims at presenting an innovative qualitative-enhanced FWI strategy that combines the benefits from these different classes of GPR processing methods. In more detail, on the one hand a synthetic aperture-based technique retrieves a first qualitative map of the buried structures. On the other hand, the dielectric properties of buried targets are found by an FWI approach formulated in the unconventional context of nonconstant-exponents Lebesgue spaces [3]. The FWI procedure exploits the qualitative map for guiding the unknown update, as well as for constructing the nonconstant-exponent function. Both numerical and experimental results are discussed to assess the proposed inversion procedure.

[1] R. Persico, Introduction to Ground Penetrating Radar: Inverse Scattering and Data Processing. Hoboken, New Jersey: Wiley, 2014.

[2] M. Pastorino and A. Randazzo, Microwave Imaging Methods and Applications. Boston, MA: Artech House, 2018.

[3] V. Schenone, A. Fedeli, C. Estatico, M. Pastorino, and A. Randazzo, “Experimental Assessment of a Novel Hybrid Scheme for Quantitative GPR Imaging,” IEEE Geoscience and Remote Sensing Letters, vol. 19, pp. 1–5, 2022.

How to cite: Fedeli, A., Schenone, V., Pastorino, M., and Randazzo, A.: Qualitative-enhanced full-waveform inversion of ground penetrating radar data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8022, https://doi.org/10.5194/egusphere-egu22-8022, 2022.

11:32–11:38
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EGU22-13149
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Presentation form not yet defined
Raffaele Persico and Giuseppe Muci

In the present contribution we will present the results of a GPR [1-3] measurement campaign performed in St. Oronzo Square, Lecce, Italy, aimed to investigate and monitor the status of the Roman amphitheatre present in the square. The “ambulacra” of this amphitheatre in particular are currently buried under the square and only partially accessible. Also, further part of the amphitheatre are still buried, and cannot be excavated because of the presence of posterior structures, in some cases of historical relevance in their turn. The georeferencing of the results has been achieved in QGIS. Indeed, no GPS was available when the measurements were performed. However, the shape of the prospected areas, wedged in the ways around the amphitheatre has allowed a correct georeferencing. A home-made MATLAB code has helped to this pros.

 

References

[1] R. Persico, S. D'Amico, L. Matera, E. Colica, C. De, Giorgio, A. Alescio, C. Sammut and P. Galea, GPR Investigations at St John's Co-Cathedral in Valletta, Near Surface Geophysics 17, 3, 2019, pp. 213-229. doi: 10.1002/nsg.12046.

[2] E. Colica, A, Antonazzo, R. Auriemma, L. Coluccia, I. Catapano, G. Ludeno, S. D’Amico, R. Persico, GPR Investigation at the Archaeological Site of Le Cesine, Lecce, Italy, Information 2021, 12, 412, https://doi.org/10.3390/info12100412

[3] G. Gennarelli, I. Catapano, F. Soldovieri, R. Persico, On the Achievable Imaging Performance in Full 3-D Linear Inverse Scattering, IEEE Trans. on Antennas and Propagation,  63, 3, March 2015, pp. 1150-1155.

How to cite: Persico, R. and Muci, G.: GPR Prospecting Close to a Roman Amphitheatre in an Urban Environment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13149, https://doi.org/10.5194/egusphere-egu22-13149, 2022.