Impact of spatial sampling and antenna polarization on 3D GPR fracture detection

Marchesini, P.; Grasmueck, Mark

doi:10.1109/icgpr.2010.5550193

Cited by 7 publications

(5 citation statements)

References 11 publications

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“…When the intervals of two dimensional scan of GPR are less than quarter wavelength of transmitting signal in the dielectric media, the subsurface 3D image with high quality can be obtained. Marchesini and Grasmuech [4] concluded that, rather than the antenna orientation, the regular and highly sampled acquisition grid for 3D GPR survey was more important for highresolution characterization of 3D fracture frameworks. But this conclusion is not proper for detecting the hidden cylinders with different orientations in the same way.…”

Section: Measurement Configurationmentioning

confidence: 99%

A circular survey for 3D ground penetrating radar to map hidden cylinders

Zhu

Wang

et al. 2013

2013 7th International Workshop on Advanced Ground Penetrating Radar

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A circular survey for 3D GPR using the linearly polarized antenna is proposed to detect and map the hidden cylinders. The backscattering signal from cylinders may strongly depend on the orientation of the cylinder relative to the antenna. The circular survey can conform to the optimal measuring condition that the long axis of the bow-tie antenna oriented is parallel to the long axis of the cylinders, and always obtain the strongest reflected signal from the cylinders. A regular survey and a circular survey using 3D GPR were carried out in the sand pit, and two crossing metal pipes were buried in dry sand as the targets. The compare results show the advantage and potential of the circular survey to detect the cylinders with the different orientations simultaneously. The fusion of the migrated result and the locations of the detected hyperbolic apices can provide more accurate mapping result of two pipes in accordance with the true scene.

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Section: Measurement Configurationmentioning

confidence: 99%

A circular survey for 3D ground penetrating radar to map hidden cylinders

Zhu

Wang

et al. 2013

2013 7th International Workshop on Advanced Ground Penetrating Radar

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“…When this is applied to our prospection in Ammaia, with average subsurface velocities of ~0.065 m ns −1 (areas 1A and 1B, surveyed in November 2010 in east–west and north–south directions, respectively, and partially overlapping; Figure ) and ~0.1 m ns −1 (area 2, surveyed in July 2011), and given the nominal centre frequency of the antennae (500 MHz), the transect spacing should be smaller than 0.0325 m and 0.05 m, respectively. In addition, the useful GPR signal contains frequency components significantly higher than the centre frequency of the antenna (Davis and Annan, ), which would reduce the profile spacing even further (Marchesini and Grasmueck, ).…”

Section: Determining the Transect Spacingmentioning

confidence: 99%

The Impact of Spatial Sampling and Migration on the Interpretation of Complex Archaeological Ground‐penetrating Radar Data

Verdonck

Taelman

Vermeulen

et al. 2015

Archaeological Prospection

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In this paper, the impact of spatial sample density and three-dimensional migration processing on the interpretation of archaeological ground-penetrating radar (GPR) data is assessed. First, the question of how to determine the sample interval required to take full advantage of the spatial resolution capabilities of GPR without oversampling is addressed. To this end, we transform a test profile into the frequency-wavenumber (f-k) domain and estimate the required sample interval from the wavenumber values. For the presented data set, collected at the Roman town Ammaia (Portugal), this resulted in a transect spacing approximately three times the distance prescribed by the λ min /4 criterion (where λ min is the minimum observed wavelength). Second, the effect of three-dimensional migration is assessed. The data set, sampled as prescribed by the analysis of the f-k plot, is migrated with two-and three-dimensional phase-shift algorithms, and the migrated results are compared with non-migrated data. It is shown that certain subtle features are better resolved by three-dimensional migration. Third, it is investigated whether three-dimensional migration following the application of an interpolation algorithm such as Delaunay triangulation or interpolation based on τ-p transform, can further relax spatial sampling requirements. For the GPR data shown in this article, it is demonstrated that interpolation and three-dimensional migration of slightly aliased data, collected with a transect spacing equal to five times the outcome of the λ min /4 criterion, still allow a faithful reconstruction of the original, non-aliased time-slices. Figure 5. Energy time-slices from between 31 and 32 ns, showing details from areas 1A and 1B, surveyed with a 0.05 m × 0.05 m grid spacing in east west and north south directions, respectively: (a and b) data after three-dimensional phase-shift migration; (c and d) data after two-dimensional phase-shift migration in in-line direction; (e and f) Unmigrated data. The large arrows show the direction of the survey lines. The numbers are explained in the text.

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“…The 8 m wide rim between pond wall and 3D GPR survey edge allows lateral movement of the infiltrated water and is also necessary for the 3D migration aperture, especially at larger depths. The 0.05 m line spacing was chosen in order to properly sample the higher than 200MHz frequency content of the GPR antennae [2,7].…”

Section: The 4d Gpr Monitored Infiltration Experimentsmentioning

confidence: 99%

4D GPR tracking of water infiltration in fractured high-porosity limestone

Grasmueck

Marchesini

Eberli

et al. 2010

Proceedings of the XIII Internarional Conference on Ground Penetrating Radar

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Three thousand liters of water were infiltrated from a 4 m diameter pond to track flow and transport inside fractured carbonates with 20-40 % porosity. Sixteen time-lapse 3D Ground Penetrating Radar (GPR) surveys with repetition intervals between 2 hrs and 5 days monitored the spreading of the water bulb in the subsurface. Based on local travel time shifts between repeated GPR survey pairs, localized changes of volumetric water content can be related to the processes of wetting, saturation and drainage. Deformation bands consisting of thin subvertical sheets of crushed grains reduce the magnitude of water content changes but enhance flow in sheet parallel direction. This causes an earlier break through across a stratigraphic boundary compared to porous limestone without deformation bands. This experiment shows how time-lapse 3D GPR or 4D GPR can non-invasively track ongoing flow processes in rock-volumes of over 100 m 3 •

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Impact of spatial sampling and antenna polarization on 3D GPR fracture detection

Cited by 7 publications

References 11 publications

A circular survey for 3D ground penetrating radar to map hidden cylinders

A circular survey for 3D ground penetrating radar to map hidden cylinders

The Impact of Spatial Sampling and Migration on the Interpretation of Complex Archaeological Ground‐penetrating Radar Data

4D GPR tracking of water infiltration in fractured high-porosity limestone

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