Measurement Of Surface Deformation Research Articles

On-line Dense 3D Reconstruction Method based on ANN us-ing a Single Structured Light Pattern

Dense 3D reconstruction techniques to measuring dynamic scenes and deformable objects with little texture have been widely studied for various applications like surface deformation measurement. We assume that the actual situation of scanning is acquiring sequential shape and measuring surface deformation online at the moment when an object deforms under the action of aerodynamic forces. This paper presents such a technique for on-line acquisition of 3D surface data based on a one-shot scanning method that reconstructs 3D shape from a single image where a simple color-coded pattern using de Bruijn sequence is projected onto an object. The proposed approach has advantages that it requires no assumption of global smoothness and continuous surface. To realize 3D reconstruction from a single image, there are sever-al issues to be solved, for example, difficulty on decoding structured light pattern because of influence of chromatic aberration in both projection systems and imaging systems, and difficul-ty on establishing accurate correspondences between projector and camera pixels. This paper describes the solutions of the issues by combining two methods, that is (1) an efficient and robust pattern decoding method based on artificial neural networks (ANN), and (2) a sub-pixel matching method using phase map and multiple view geometry. Furthermore, we adopt some effective strategies to improve algorithm robustness. Practical experiments were carried out to test the accuracy and efficiency of the scanning system in typical configuration. The results show that the scanning system can reconstruct 3D shape on-line in high-resolution with the accuracy of 0.09 mm and efficiency of 10 fps.

Surface deformation of the Barren Island volcano, Andaman Sea (2007–2017) constrained by InSAR measurements: Evidence for shallow magma reservoir and lava field subsidence

Barren Island, situated in the Andaman Sea, is the northernmost active volcano of the Sunda arc. The oldest known eruption of the volcano was during the period 1787–1832. After about 150 years of quiescence, volcanic activity resumed in 1991 and continues since then. The magmatic plumbing system of this volcano is largely unknown due to lack of geophysical experiments owing to its remote location. We report, for the first-time, time-series surface deformation measurements of Barren Island volcano from interferometric synthetic aperture radar (InSAR) during epochs 2007–2011 and 2015–2017. Line-of-Sight (LOS) deformation of −50 mm/yr during 2007–2011 at the cinder cone is interpreted as the co-eruptive pressure changes associated with the 2008–2010 eruptions. Bayesian inversion suggests a shallow magma reservoir at a depth of 578−100+300 m below the summit. The depth of the magma reservoir is shallower than that of other volcanoes of the Sunda arc, probably due to the extensional stress regime imposed by the oblique subduction. Based on the present studies and previous works, we propose a plausible source model for Barren Island volcano. We also discuss potential biases in the present source parameter estimation due to the lack of high quality InSAR data from both ascending and descending directions. Significant deformation (−15 to −150 mm/yr) observed along the lava delta of Barren Island volcano for both the epochs are interpreted as post-emplacement subsidence of the lava flow. Further, we characterise the lava flow including volcanic deposits by mapping its spatial extent and elevation changes during 1979–2000 and 2000–2017 periods using geodetic measurements.

Corrigendum: Ionospheric correction of ALOS‐2 full‐aperture ScanSAR interferometric data for surface deformation measurement in Beijing

Corrigendum: Ionospheric correction of ALOS‐2 full‐aperture ScanSAR interferometric data for surface deformation measurement in Beijing

Bayesian Poroelastic Aquifer Characterization From InSAR Surface Deformation Data. Part I: Maximum A Posteriori Estimate

AbstractCharacterizing the properties of groundwater aquifers is essential for predicting aquifer response and managing groundwater resources. In this work, we develop a high‐dimensional scalable Bayesian inversion framework governed by a three‐dimensional quasi‐static linear poroelastic model to characterize lateral permeability variations in groundwater aquifers. We determine the maximum a posteriori (MAP) point of the posterior permeability distribution from centimeter‐level surface deformation measurements obtained from Interferometric Synthetic Aperture Radar (InSAR). The scalability of our method to high parameter dimension is achieved through the use of adjoint‐based derivatives, inexact Newton methods to determine the MAP point, and a Matérn class sparse prior precision operator. Together, these guarantee that the MAP point is found at a cost, measured in number of forward/adjoint poroelasticity solves, that is independent of the parameter dimension. We apply our methodology to a test case for a municipal well in Mesquite, Nevada, in which InSAR and GPS surface deformation data are available. We solve problems with up to320,824state variable degrees of freedom (DOFs) and16,896parameter DOFs. A consistent treatment of noise level is employed so that the aquifer characterization result does not depend on the pixel spacing of surface deformation data. Our results show that the use of InSAR data significantly improves characterization of lateral aquifer heterogeneity, and the InSAR‐based aquifer characterization recovers complex lateral displacement trends observed by independent daily GPS measurements.

Dual beam-shear differential interference microscopy for full-field surface deformation gradient characterization

We propose a new experimental mechanics method: dual beam-shear differential interference microscopy (DInM) for full-field surface deformation measurement. The method integrates the principles of differential interference contrast, photoelasticity, digital image correlation and the theories of continuum mechanics for a 4D quantification of the surface topography. Our first DInM prototype provides the lateral resolution of 787nm for up to 12% measurable out-of-plane strains. The resolution can be improved by using the shorter spectrum light and higher magnification objective lens. We use our system to characterize the buckling profile of Si microribbon on an elastomer substrate, which was verified by atomic force microscopy. We also demonstrate the stress-induced phase transformation in NiTi alloy by our system. The evolution of the surface topographies and the full-field deformation gradients are successfully captured and quantified. The dynamic measurement provides the information to calculate the relative transformation strains between phases of different symmetries. The establishment of dual beam-shear DInM opens a new avenue in the field of experimental meso/micromechanics.

Institute of Mining and Chemical Industry

Introduction. There are the speleological and engineering-geological areas in karst studies. Engineeringgeological area has two aspects, the surface aspect including the construction of surface buildings in the areas with the karst hazard and the subsurface aspect of prevention and protection from karstification when developing mineral deposits. Although shafts in salt mines has been working since the Middle Ages, the salt karst is still the reason for the destruction of a lot of salt mines. Research aim is to reveal the physical and chemical mechanism of salt karst development and the reasons for accidents and flooding in salt mines. Methodology included the analysis of regular survey measurements of surface deformation, recording of brine manifestations in mine workings, chemical analyses in brines, hydraulic measurements at surface watercourses, direct determinations of brine aggression, geophysical research by the natural field method, vertical electrical sounding, etc. In recent years, in order to control surface deformation, the data from the radar survey have been used. Results. A clue to the mechanism of salt karst responsible for accidents is the theory of hydrodynamic systems by A. M. Ovchinnikov, the elements of which are the areas of accumulation, transit, and discharge. Brine motion is in the supra-salt reservoir. The trajectory of brine motion is determined by the relief of the salt table. Pressure flow take up the elevated terrain. Accumulation areas are confined to stream corridors permeating the low-permeability strata which covers the salt. The area of transit distinguishes between the zone of the pressure flow and the vertical slot where the brines move in the gravity turbulent conditions. Mine workings make up the discharge area. Within them under the action of aggressive brines triangular niches develop. Pillars undercut results in their collapse and surface sink. Summary. Salt karst development mechanism disclosure has made it possible to propose the methods for predicting its effect and the ways of predicting flooding in salt mines.

A technique for in situ X-ray computed tomography of deformation-induced cavitation in thermoplastics

Deformation-induced cavitation influences the mechanical response of polymeric materials, but acquiring in situ measurements of the spatial evolution of cavities has typically necessitated the use of synchrotron radiation sources. The objective of this study is to develop and demonstrate a method allowing for in situ measurements of deformation-induced cavitation in axisymmetric polymer specimens, using a home-laboratory X-ray computed tomography setup. The method is demonstrated by assessing deformation-induced cavitation of mineral-filled PVC in a repeated loading-unloading experiment. A temporal resolution of about 3 s is obtained by exploiting the axisymmetry of notched round tensile specimens. The evolution of relative density was captured throughout the experiment, revealing an interplay between void nucleation and void growth. Combined with surface deformation measurements obtained by digital image correlation, the present technique yields data suitable for calibration and validation of material models.

Resolving the Kinematics and Moment Release of Early Afterslip Within the First Hours Following the 2016 Mw 7.1 Kumamoto Earthquake: Implications for the Shallow Slip Deficit and Frictional Behavior of Aseismic Creep

AbstractAs stresses following rupture are dissipated continuous measurements of postseismic surface deformation provide insight into variations of the frictional strength of faults and the rheology of the lower crust and upper mantle. Due to the difficulty of capturing the earliest phase of afterslip, most analyses have focused on understanding postseismic processes over timescales of weeks to years. Here we investigate the kinematics, moment release, and frictional properties of the earliest phase of afterslip within the first hours following the 2016 Mw 7.1 Kumamoto earthquake using a network of 5‐minute sampled continuous Global Positioning System (GPS) stations. Using independent component analysis to filter the GPS data, we find that (1) early afterslip contributes only ~1% of total moment release within the first hour and 8% after 24 hr. This suggests that the lack of a coseismic slip deficit, which we estimate using standard geodetic data sets (e.g., InSAR, GPS, and pixel offsets) and which span the first 4 days of the postseismic period, is largely reflective of the dynamic rupture process and we can rule out contamination of moment release by early afterslip. (2) Early afterslip shows no evidence of a delayed nucleation or acceleration phase, where instead fault patches transition to immediate deceleration following rupture that is consistent with frictional relaxation under steady state conditions with dependence only on the sliding velocity. (3) There is a close correlation between the near‐field aftershocks and afterslip within the first hours following rupture, suggesting afterslip may still be an important possible triggering mechanism during the earliest postseismic period.

InSAR-based detection method for mapping and monitoring slow-moving landslides in remote regions with steep and mountainous terrain: An application to Nepal

Mapping and monitoring landslides in remote areas with steep and mountainous terrain is logistically challenging, expensive, and time consuming. Yet, in order to mitigate hazards and prevent loss of life in these areas, and to better understand landslide processes, high-resolution measurements of landslide activity are necessary. Satellite-based synthetic aperture radar interferometry (InSAR) provides millimeter-scale measurements of ground surface deformation that can be used to identify and monitor landslides in remote areas where ground-based monitoring techniques are not feasible. Here we present a novel InSAR deformation detection approach, which uses double difference time-series with local and regional spatial filters and pixel clustering methods to identify and monitor slow-moving landslides without making a priori assumptions of the location of landslides. We apply our analysis to freely available Copernicus Sentinel-1 satellite data acquired between 2014 and 2017 centered on the Trishuli River drainage basin in Nepal. We found a minimum of 6 slow-moving landslides that all occur within the Ranimatta lithologic formation (phyllites, metasandstones, metabasics). These landslides have areas ranging from 0.39 to 1.66 km2 and long-term dry-season displacement rates ranging from 2.1 to 8.8 cm/yr. Due to periods of low coherence during the monsoon season (June – September) each year, and following the 25 April 2015 Mw7.8 Gorkha earthquake, our time series analysis is limited to the 2014–2015 and 2016–2017 dry seasons (September–May). We found that each of the landslides displayed slightly higher rates during the 2014 period, likely as a result of higher cumulative rainfall that fell during the 2014 monsoon season. Although we do not have high quality InSAR data to show the landslide evolution directly following the Gorkha earthquake, the similar rates of movement before (2014–2015) and after (2016–2017) Gorkha suggest the earthquake had negligible long-term impact on these landslides. Our findings highlight the potential for region-wide mapping of slow-moving landslides using freely available remote sensing data in remote areas such as Nepal and future work will benefit from expanding our methodology to other regions around the world.

Precise Three-Dimensional Deformation Retrieval in Large and Complex Deformation Areas via Integration of Offset-Based Unwrapping and Improved Multiple-Aperture SAR Interferometry: Application to the 2016 Kumamoto Earthquake

Abstract Conventional synthetic aperture radar (SAR) interferometry (InSAR) has been successfully used to precisely measure surface deformation in the line-of-sight (LOS) direction, while multiple-aperture SAR interferometry (MAI) has provided precise surface deformation in the along-track (AT) direction. Integration of the InSAR and MAI methods enables precise measurement of the two-dimensional (2D) deformation from an interferometric pair; recently, the integration of ascending and descending pairs has allowed the observation of precise three-dimensional (3D) deformation. Precise 3D deformation measurement has been applied to better understand geological events such as earthquakes and volcanic eruptions. The surface deformation related to the 2016 Kumamoto earthquake was large and complex near the fault line; hence, precise 3D deformation retrieval had not yet been attempted. The objectives of this study were to (1) perform a feasibility test of precise 3D deformation retrieval in large and complex deformation areas though the integration of offset-based unwrapped and improved multiple-aperture SAR interferograms and (2) observe the 3D deformation field related to the 2016 Kumamoto earthquake, even near the fault lines. Two ascending pairs and one descending the Advanced Land Observing Satellite-2 (ALOS2) the Phased Array-type L-band Synthetic Aperture Radar-2 (PALSAR2) pair were used for the 3D deformation retrieval. Eleven in situ Global Positioning System (GPS) measurements were used to validate the 3D deformation measurement accuracy. The achieved accuracy was approximately 2.96, 3.75, and 2.86 cm in the east, north, and up directions, respectively. The results show the feasibility of precise 3D deformation measured through the integration of the improved methods, even in a case of large and complex deformation.

Measuring Pavement Permanent Deformation in Accelerated Pavement Testing

Permanent deformation is an essential criterion for evaluating pavement performance. In an accelerated pavement testing (APT) experiment at the Virginia Tech Transportation Institute, a laser profiler, multi-depth deflectometer (MDD), and forensic investigation were used to measure the permanent deformation of a pavement system. This paper analyzes the permanent deformation measured via the three methods during the APT experiment. The major concern among the three methods is applicability rather than accuracy. To measure surface deformation, the laser profiler is a more practical method than MDD in APT, as it can scan the whole surface instead of just one point. To measure the deformation within a pavement structure, MDD provides deformation development throughout the whole experiment, which is helpful for a deeper understanding of pavement materials and structures. However, MDD is also more expensive and requires significant installation effort and maintenance during the experiment compared with forensic investigation, which also needs to be considered.

An Improved Two-Step Multitemporal SAR Interferometry Method for Precursory Slope Deformation Detection Over Nanyu Landslide

A major landslide in Nanyu township, Zhouqu county, Western China, occurred on July 12, 2018, causing widespread damage and blocking the Bailong river. As a widely used surface deformation measurement technique, persistent scatterer interferometry (PSI) method fails in the precursory slope deformation detection over Nanyu landslide for two reasons: the high rate slope deformation of the landslide body before the occurrence of the disaster and the low density of measurement points in the widespread nonurban regions over hillside area. To solve these problems, a two-step multitemporal interferometric synthetic aperture radar (MTInSAR) method is proposed in this letter. In the proposed method, first, a carefully designed small baseline subsets (SBASs) method is applied to extract the linear high rate deformation component, which is then subtracted from the wrapping interferogram to reduce the likelihood of signal aliasing. In the second step, a two-tier network-based MTInSAR method by exploiting both persistent scatterers (PSs) and distributed scatterers (DSs) is employed to retrieve the residual deformation. The proposed method is applied to 47 Sentinel-1 images acquired between December 2016 and July 2018 and successfully detects the precursory deformation over Nanyu landslide for the first time. Experiment results illustrate the advantage of the proposed method for measuring high rate deformation compared with the traditional PSI. By using the proposed algorithm, the deformation rate map shows a clear landslide boundary and precursors of the rapid slope movements with a maximum displacement rate of 483 mm/year along the line of sight of the satellite.

Recursive-iterative digital image correlation based on salient features

Measuring surface deformation of objects with natural patterns using digital image correlation (DIC) is difficult due to the challenges of the pattern quality and discriminative pattern matching. Existing studies in DIC predominantly focus on the artificial speckle patterns while seldom paying attention to the inevitable natural texture patterns. We propose a recursive-iterative method based on salient features to measure the deformation of objects with natural patterns. The method is proposed to select salient features according to the local intensity gradient and then to compute their displacements by incorporating the inverse compositional Gauss–Newton (IC-GN) algorithm into the classic image pyramidal computation. Compared with the existing IC-GN-based DIC technology, the use of discriminative subsets allows avoidance of displacement computation at pixels with poor spatial gradient distribution. Furthermore, the recursive computation based on the image pyramid can estimate the displacements of the features without the need for initial value estimation. This method remains effective even for large displacement measurements. The results of simulation and experiment prove the method’s feasibility, demonstrating that the method is effective in deformation measurement based on natural texture patterns.

Use of SAR/InSAR in Mining Deformation Monitoring, Parameter Inversion, and Forward Predictions: A Review

Ground surface deformation monitoring, parameter inversion, and forward prediction are essential to mining deformation mechanism interpretation and its related geohazard assessment. Interferometric synthetic aperture radar (InSAR) has the capability to measure surface deformation in a very wide area with high spatial resolution, low cost, and high efficiency, which traditional geodetic surveying techniques cannot accomplish. Consequently, InSAR offers great potential for promoting, or even revolutionizing, traditional mining deformation monitoring and forward prediction, with great efforts having been made in this field.

Study of Systematic Bias in Measuring Surface Deformation With SAR Interferometry

This article investigates the presence of a new interferometric signal in multilooked synthetic aperture radar (SAR) interferograms that cannot be attributed to the atmospheric or Earth-surface topography changes. The observed signal is short-lived and decays with the temporal baseline; however, it is distinct from the stochastic noise attributed to temporal decorrelation. The presence of such a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fading signal</i> introduces a systematic phase component, particularly in short temporal baseline interferograms. If unattended, it biases the estimation of Earth surface deformation from SAR time series. Here, the contribution of the mentioned phase component is quantitatively assessed. The biasing impact on the deformation-signal retrieval is further evaluated. A quality measure is introduced to allow the prediction of the associated error with the fading signals. Moreover, a practical solution for the mitigation of this physical signal is discussed; special attention is paid to the efficient processing of Big Data from modern SAR missions such as Sentinel-1 and NISAR. Adopting the proposed solution, the deformation bias is shown to decrease significantly. Based on these analyses, we put forward our recommendations for efficient and accurate deformation-signal retrieval from large stacks of multilooked interferograms.

Hybrid Digital Image Correlation

AbstractDigital image correlation (DIC) is a commonly used full-field technique for measuring surface deformations in experimental solid mechanics. It directly provides full-field displacements by ...

Measurement of three-dimensional surface deformation of ceramic materials by digital image correlation (DIC) method

Measurement of three-dimensional surface deformation of ceramic materials by digital image correlation (DIC) method

Application of 3D Projection Profilometry in the High Speed Impaction Surface Deformation Measurement Research

In order to study the strength of the composite material plate problems, need to adopt a nondestructive testing method to obtain the specimen surface under the effect of high-speed impact regularity of shape. The projection profilometry was used to measure the surface profile or the full field deformation. Furtherly, by using the Fourier transform algorithm, there is only one frame of captured image which is needed in the measurement, so that it can be introduced into the high speed impaction procedure measurement. An experimental system, which was contained with an impact setup and the projection profilometry measurement part, was constructed for the impaction action characteristic research. The metallic impact object can be launched by a gas gun or a spin fan, respectively. The detected object is manufactured by composite materials. In order to increase the surface deformation measurement accuracy, the calibration method and the error was discussed with different calibration specimen. And then, the proposed profilometry measurement method is proved by the gas gun and spin fan projectile test. The surface deformation of the manufactured composite plates and fan case are measured in the impaction procedure. So that the impact action details can be described much more clearly than the traditional video monitoring method.

Surface Pressure Reconstruction from Phase Averaged Deflectometry Measurements Using the Virtual Fields Method

In this study, pressure distributions were reconstructed from phase-locked surface deformation measurements on a thin plate. Slope changes on the plate surface were induced by an external flow interacting with the specimen and measured with a highly sensitive deflectometry setup. The Virtual Fields Method (VFM) was used to obtain pressure reconstructions from the processed surface slopes and the plate material constitutive mechanical parameters. The applicability of the approach in combination with phase-locked measurements is demonstrated using a synthetic jet setup generating a periodic flow in air. Phase-averaging slope data allows mitigating random noise effects and resolving low-range differential pressure amplitudes despite the turbulent flow. The size of the spatial structures of the investigated low amplitude flow events identified in full-field with the present method are mathcal {O}(1)~text {mm}, which is beyond the capabilities of other available surface pressure measurement techniques. Challenges and limitations in achieving the metrological performance for resolving the observed surface slopes of mathcal {O}(0.1)~text {mm km}^{-1} are described and improvements for future applications are discussed.

Sentinel-1 interferometry with ionospheric correction from global and local TEC maps for land displacement detection in Taiwan

Sentinel-1 satellite launched by the European Space Agency (ESA) offers an opportunity to apply the differential interferometric synthetic aperture radar (DInSAR) in 12-day revisit, a potential solution to effectively measure surface deformation. However, for areas affected by the Equatorial Ionization Anomaly (EIA) in a global ionosphere pattern, the total electron content (TEC) irregularity between snapshots may induce extra fringes and further mislead the unwrapping and displacement results. To test the necessity of ionospheric correction, we utilize global and regional ionospheric vertical TEC maps, namely the Global Ionosphere Map (GIM) released by the International GNSS Service and the Taiwan Regional Ionospheric Map (TRIM) provided by a local GNSS network, to compensate ionospheric phases in the interferograms.Our experiments investigate 47 ascending image pairs in 2016 and 2017. Among them, two pairs of images whose differenced TEC (ΔTEC) stronger than 16.73 TEC unit in azimuthal gradient contain the clearest extra fringes. The results show that TRIM outperforms in reducing extra fringes caused by the ionospheric effect, with a root-mean-square error (RMSE) of the estimated satellite line-of-sight displacement reduced from 105.03 mm to 9.94 mm as compared against ground truth data. We conclude that TRIM TEC map is able to remove long-wavelength background of ionosphere-induced displacement when a differenced TEC gradient larger than an empirical threshold of 15 TECU.