Levelling aeromagnetic survey data without the need for tie‐lines

White, James C.; Beamish, David

doi:10.1111/1365-2478.12198

Cited by 21 publications

(12 citation statements)

References 16 publications

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“…Standard processing steps were applied to each sub-survey UAV magnetic data set ( Figure 9): (i) Time-stamping and positioning, including parallax correction, (ii) Despiking of erroneous GNSS and magnetic values, (iii) Diurnal correction, (iv) Correction of the main and super-regional magnetic field using the CHAOS X7 model of [29], (v) Moving mean filter and downsampling from 200 to 40 Hz, (vi) Survey line trimming, (vii) Survey line leveling using six iterations of the approach of [30] (see example in Figure S6, Supplementary Data), (viii) Micro-leveling [31], and (ix) reduction-to-pole. All processing and plotting was carried out using Matlab R2019b and Python.…”

Section: Uav Magnetic Datamentioning

confidence: 99%

A High-Speed, Light-Weight Scalar Magnetometer Bird for km Scale UAV Magnetic Surveying: On Sensor Choice, Bird Design, and Quality of Output Data

et al. 2021

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Magnetic surveying is a widely used and cost-efficient remote sensing method for the detection of subsurface structures at all scales. Traditionally, magnetic surveying has been conducted as ground or airborne surveys, which are cheap and provide large-scale consistent data coverage, respectively. However, ground surveys are often incomplete and slow, whereas airborne surveys suffer from being inflexible, expensive and characterized by a reduced signal-to-noise ratio, due to increased sensor-to-source distance. With the rise of reliable and affordable survey-grade Unmanned Aerial Vehicles (UAVs), and the developments of light-weight magnetometers, the shortcomings of traditional magnetic surveying systems may be bypassed by a carefully designed UAV-borne magnetometer system. Here, we present a study on the development and testing of a light-weight scalar field UAV-integrated magnetometer bird system (the CMAGTRES-S100). The idea behind the CMAGTRES-S100 is the need for a high-speed and flexible system that is easily transported in the field without a car, deployable in most terrain and weather conditions, and provides high-quality scalar data in an operationally efficient manner and at ranges comparable to sub-regional scale helicopter-borne magnetic surveys. We discuss various steps in the development, including (i) choice of sensor based on sensor specifications and sensor stability tests, (ii) design considerations of the bird, (iii) operational efficiency and flexibility and (iv) output data quality. The current CMAGTRES-S100 system weighs ∼5.9 kg (including the UAV) and has an optimal surveying speed of 50 km/h. The system was tested along a complex coastal setting in Brittany, France, targeting mafic dykes and fault contacts with magnetite infill and magnetite nuggets (skarns). A 2.0 × 0.3 km area was mapped with a 10 m line-spacing by four sub-surveys (due to regulatory restrictions). The sub-surveys were completed in 3.5 h, including >2 h for remobilisation and the safety clearance of the area. A noise-level of ±0.02 nT was obtained and several of the key geological structures were mapped by the system.

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Section: Uav Magnetic Datamentioning

confidence: 99%

A High-Speed, Light-Weight Scalar Magnetometer Bird for km Scale UAV Magnetic Surveying: On Sensor Choice, Bird Design, and Quality of Output Data

et al. 2021

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“…Arguably, data acquisition quality has evolved to the point where feature confirmation is no longer an issue; and data precision can be estimated by other methods. White and Beamish (2015) described a methodology to level airborne magnetic data without orthogonal tie-lines.…”

Section: Conclusion Consequences and Contemplationsmentioning

confidence: 99%

Airborne gravimetry takes off in the Western Australia ‘Generation 2’ reconnaissance gravity mapping project

Hondula

Brett

Lane

et al. 2018

ASEG Extended Abstracts

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In 1974, the Australian Bureau of Mineral Resources, Geology and Geophysics completed a 15-year systematic reconnaissance gravity survey of Australia with stations spaced at 11 km. The 1976 Gravity Map of Australia was a seminal product; half a century later, the data still provide the only coverage for substantial parts of the continent. In 2005, the Geological Survey of Western Australia, supported by Geoscience Australia, commenced a program of regional ground gravity surveys with 2.5 km station spacing, a sixteen-fold improvement of resolution over the 'first generation' BMR data. In 2013, GSWA declared its aim of completing 'second-generation' reconnaissance gravity coverage of WA by 2020. In 2016, with 45% of the State yet to be surveyed in the north and east, and ground access issues slowing progress and making uniform coverage increasingly difficult, GSWA and GA undertook the first government-commissioned regional aerogravity survey in Australia, using the Sander Geophysics AIRGrav system. The 38,000 line-km survey covering 84,000 km 2 in the East Kimberley region was flown at 2.5 km line-spacing for compatible spatial resolution with GSWA's regional ground surveys. We compare airborne with ground gravimetry in the context of the East Kimberley project and conclude that, for reconnaissance surveys: aerogravity costs now approach those of ground surveys; spatial resolution is equivalent; data precision is not a critical factor; and airborne and ground data can be merged seamlessly for interpretation. Consequently, new aerogravity surveys were commissioned over 264,000 km 2 of northern WA in the Tanami, northeast Canning and Kidson regions.

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“…One reason for the inadequacy of tie-line leveling is that the leveling errors cannot be expected to cancel out using only two repetitive trials at the intersection point, in a statistical sense. Some other authors (e.g., in [8]) have also noticed that tie-line leveling is ineffective due to strong gradients in the anomaly field and the low flight altitude at which modern surveys may operate. In addition, we find that it has the following problems that need to be further clarified.…”

Section: Inadequacy Of Tie-line Levelingmentioning

confidence: 99%

“…For example, in [8] and [9], the leveling errors are modeled by a low-order polynomial to minimize line-to-line differences; in [10] and [11], a circle with adjustable radius is utilized to extract the leveling errors point by point from the different information between the area in the circle window and the corresponding line within the circle [see Fig. 2(b)], which can be interpreted as low-order (0, 1, and 2) differential polynomial fitting (DPF) and have shown the best performance in preserving along-line-elongated signals among these methods.…”

Section: B On Modeling Leveling Errorsmentioning

confidence: 99%

“…Some geophysical researchers have developed a variety of methods to level aeromagnetic data without the need for tie lines [8]- [11]. However, a main setback when leveling without tie lines is to distinguish the cross-line gradients from the leveling errors, making the methods incapable of preserving useful along-line-elongated geologic signals.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Elaborately Designed Virtual Frame to Level Aeromagnetic Data

Fan

Huang

Zhang

et al. 2016

IEEE Geosci. Remote Sensing Lett.

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Aeromagnetic data are usually contaminated by lineto-line errors, which are most often visible as stripe patterns in a 2-D data map. Leveling is a critical step to eliminate these errors in data processing and interpretation. The conventional tie-line leveling technique involves control lines (tie lines) which are perpendicular to flight lines to extract the leveling errors. By contrast, there are also some other methods to level without the need for tie lines, which can save considerable survey cost. However, a main setback when leveling without tie lines is to distinguish the crossline gradients from the leveling errors, making the leveled results inferior. In this letter, we revisit tie-line leveling as a nonlinear spatial-filtering technique and analyze the inadequacy of it, based on which a new approach is developed to extract the leveling errors without additional tie lines. The approach includes two steps: designing a virtual frame and leveling based on this frame. The virtual frame is elaborately designed to ensure that each extracted point can represent the local field-intensity level of a flight line and each virtual cross line can bypass the localized areas of magnetic anomalies; hence, some difficulties when leveling without tie lines are overcome. Afterward, two real field data examples are tested to demonstrate the effectiveness of this approach.

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Levelling aeromagnetic survey data without the need for tie‐lines

Cited by 21 publications

References 16 publications

A High-Speed, Light-Weight Scalar Magnetometer Bird for km Scale UAV Magnetic Surveying: On Sensor Choice, Bird Design, and Quality of Output Data

A High-Speed, Light-Weight Scalar Magnetometer Bird for km Scale UAV Magnetic Surveying: On Sensor Choice, Bird Design, and Quality of Output Data

Airborne gravimetry takes off in the Western Australia ‘Generation 2’ reconnaissance gravity mapping project

An Elaborately Designed Virtual Frame to Level Aeromagnetic Data

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