Gravity for Detecting Caves: Airborne and Terrestrial Simulations Based on a Comprehensive Karstic Cave Benchmark

Braitenberg, Carla; Sampietro, Daniele; Pivetta, Tommaso; Zuliani, David; Barbagallo, Alfio; Fabris, Paolo; Rossi, Lorenzo; Fabbri, Julius; Mansi, Ahmed Hamdi

doi:10.1007/s00024-015-1182-y

Cited by 29 publications

(16 citation statements)

References 17 publications

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“…Such applications require, in order to reach millimeter-level accuracy, the deployment of stationary GNSS units, delivering raw observations, and the processing of sufficiently short baselines [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. However, for more traditional surveying operations, such as map updates [ 8 ], cadastral or archaeological surveys [ 9 , 10 ], or surveys to support other measurements, e.g., gravimetric networks [ 11 ], significantly lower accuracies, e.g., of the order of tens of centimeters, are sufficient. This accuracy level can be easily reached by single-frequency GNSS receiver observations, by means of acquisitions performed in a fast static mode (e.g., over a timespan of 10–15 min), opportunely elaborated in a classic relative positioning processing, i.e., by double-differencing observations with those coming from a GNSS CORS (Continuously Operating Reference Station).…”

Section: Introductionmentioning

confidence: 99%

Precise GNSS Positioning Using Smart Devices

Realini¹,

Caldera²,

Pertusini³

et al. 2017

Sensors

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107

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The recent access to GNSS (Global Navigation Satellite System) phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether this is feasible, and which positioning accuracy can be achieved by relative positioning of the smart device with respect to a base station. Positioning of a Google/HTC Nexus 9 tablet was performed by means of batch least-squares adjustment of L1 phase double-differenced observations, using the open source goGPS software, over baselines ranging from approximately 10 m to 8 km, with respect to both physical (geodetic or low-cost) and virtual base stations. The same positioning procedure was applied also to a co-located u-blox low-cost receiver, to compare the performance between the receiver and antenna embedded in the Nexus 9 and a standard low-cost single-frequency receiver with external patch antenna. The results demonstrate that with a smart device providing raw GNSS phase observations, like the Nexus 9, it is possible to reach decimeter-level accuracy through rapid-static surveys, without phase ambiguity resolution. It is expected that sub-centimeter accuracy could be achieved, as demonstrated for the u-blox case, if integer phase ambiguities were correctly resolved.

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Section: Introductionmentioning

confidence: 99%

Precise GNSS Positioning Using Smart Devices

Realini¹,

Caldera²,

Pertusini³

et al. 2017

Sensors

Self Cite

107

View full text Add to dashboard Cite

show abstract

“…The cross-line spacing is 4.5 km for all survey lines, except the west-east lines, which were spaced at 20 km. The west-east lines were used mainly for crossover analyses, which reduces the mis-fitting of the observed gravity signal that could be mistakenly considered as colored noise [24]. The cross-line spacing of 4.5 km equals to the theoretical resolvable wavelength of the gravity anomaly at the flight altitude, which was approximately 5156 m. The RMS of crossover differences was 2.88 mGal, corresponding to a 2 mGal STD error in terms of the gravity anomaly.…”

Section: Real Airborne Gravity Data In Taiwanmentioning

confidence: 99%

“…Among those issues, the downward continuation error is the biggest factor affecting the geodetic and geophysical applications of airborne gravimetry. In airborne gravimetry, gravity anomalies are collected above the mean sea level and commonly downward continuation to the earth surface before exploiting it in geodesy and geophysics is needed [15][16][17][18][19][20][21][22][23][24]. Without a proper method, downward continued gravity data will contain false gravity signals that would lead to erroneous geophysical interpretations [1].…”

Section: Introductionmentioning

confidence: 99%

Improvement of Downward Continuation Values of Airborne Gravity Data in Taiwan

Zhao

Forsberg

et al. 2018

Remote Sensing

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An airborne gravity survey was carried out to fill gaps in the gravity data for the mountainous areas of Taiwan. However, the downward continuation error of airborne gravity data is a major issue, especially in regions with complex terrain, such as Taiwan. The root mean square (RMS) of the difference between the downward continuation values and land gravity was approximately 20 mGal. To improve the results of downward continuation we investigated the inverse Poisson’s integral, the semi-parametric method combined with regularization (SPR) and the least-squares collocation (LSC) in this paper. The numerically simulated experiments are conducted in the Tibetan Plateau, which is also a mountainous area. The results show that as a valuable supplement to the inverse Poisson’s integral, the SPR is a useful approach to estimate systematic errors and to suppress random errors. While the LSC approach generates the best results in the Tibetan Plateau in terms of the RMS of the downward continuation errors. Thus, the LSC approach with a terrain correction (TC) is applied to the downward continuation of real airborne gravity data in Taiwan. The statistical results show that the RMS of the differences between the downward continuation values and land gravity data reduced to 11.7 mGal, which shows that an improvement of 40% is obtained.

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“…Page 3, L.2-5: here different geophysical methods that are useful to define morphology of cavities and sinkhole fills are mentioned, but the gavity method is lacking. Please include it, for instance with Braitenberg et al 2016, andPivetta et al2015. Page 5, L.10:" structures regional scattered": check Grammar.…”

Section: Minor Specific Commentsmentioning

confidence: 99%

Short Review

Braitenberg¹

2018

Preprint

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The working hypothesis of this fine example of repeated gravity measurements is, that the mass loss accompanying the formation of cavities is measurable. The measurement campaign is carried out over four years (2014-2018) in a karst area in Germany affected by the formation of sinkholes and active ground subsidence. These bear a hazard to the buildings and infrastructure, as suddenly the roof of the cavities can collapse creating a hole of many meters depth and bringing down buildings or streets located above the cave. The subsidence is documented by a precise repeat levelling C1

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Gravity for Detecting Caves: Airborne and Terrestrial Simulations Based on a Comprehensive Karstic Cave Benchmark

Cited by 29 publications

References 17 publications

Precise GNSS Positioning Using Smart Devices

Precise GNSS Positioning Using Smart Devices

Improvement of Downward Continuation Values of Airborne Gravity Data in Taiwan

Short Review

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