scholarly journals EXTRACTING AND EVALUATING CLUSTERS IN DINSAR DEFORMATION DATA ON SINGLE BUILDINGS

2020 ◽  
Vol V-3-2020 ◽  
pp. 157-163
Author(s):  
P. J. Schneider ◽  
R. Khamis ◽  
U. Soergel
Keyword(s):  
Ground Truth ◽  
Deformation Space ◽  
Powerful Method ◽  
Persistent Scatterer Interferometry ◽  
Ground Truth Data ◽  
Precise Levelling ◽  
The Past ◽  
Persistent Scatterer ◽  
Displacement Patterns ◽  
Insight Into

Abstract. In the past two decades persistent scatterer interferometry (PSI) has become a well understood and powerful method to monitor the deformations of man-made structures. PSI can derive displacement histories of thousands of scattered points on a single building with accuracy of a few millimetre per year, by analysing space-borne SAR data. In this paper, we present a method to cluster PS points on a single building into segments which show the same deformation behavior. The spatial distribution of those clusters gives an insight into the structural behavior of a building. We use dimensionality reduction to visualize the clusters in the deformation space. The comparison of our extracted displacement patterns with ground truth data from precise levelling and 3D tachymetry confirms the plausibility of our remote sensing method.

scholarly journals Detection of terrain changes in southern Denmark using persistent scatterer interferometry

1969 ◽  
Vol 23 ◽  
pp. 41-44
Author(s):  
Stig A. Schack Pedersen ◽  
Geraint Cooksley ◽  
Marc Gaset ◽  
Peter Roll Jakobsen
Keyword(s):  
Environmental Monitoring ◽  
Persistent Scatterer Interferometry ◽  
The Past ◽  
The Earth ◽  
Satellite Repeats ◽  
Persistent Scatterer

Since 1991, a number of European satellites have acquired data of the Earth’s surface for environmental monitoring. In general, a satellite will orbit the Earth in about 1½ hours and it takes 35 days before an ERS or ENVISAT satellite repeats radar scanning of the same position. For younger generations of satellites, such as RADARSAT and TERRA, the scanning repeat interval has decreased to 24 and 11 days, respectively, so that hundreds of radar scenes of the same place, produced over the past c. 20 years, are now available.

scholarly journals Improving PSI Processing of Mining Induced Large Deformations with External Models

2020 ◽  
Vol 12 (19) ◽  
pp. 3145
Author(s):  
Sen Du ◽  
Jordi J. Mallorqui ◽  
Hongdong Fan ◽  
Meinan Zheng
Keyword(s):  
Ground Deformation ◽  
Ground Truth ◽  
Deformation Monitoring ◽  
Persistent Scatterer Interferometry ◽  
Mining Operations ◽  
Sar Images ◽  
Temporal Behaviour ◽  
Persistent Scatterer ◽  
Large Gradient ◽  
External Model

Ground subsidences, either caused by natural phenomena or human activities, can threaten the safety of nearby infrastructures and residents. Among the different causes, mining operations can trigger strong subsidence phenomena with a fast nonlinear temporal behaviour. Therefore, a reliable and precise deformation monitoring is of great significance for safe mining and protection of facilities located above or near the mined-out area. Persistent Scatterer Interferometry (PSI) is a technique that uses stacks Synthetic Aperture Radar (SAR) images to remotely monitor the ground deformation of large areas with a high degree of precision at a reasonable cost. Unfortunately, PSI presents limitations when monitoring large gradient deformations when there is phase ambiguity among adjacent Persistent Scatterer (PS) points. In this paper, an improvement of PSI processing, named as External Model-based Deformation Decomposition PSI (EMDD-PSI), is proposed to address this limitation by taking advantage of an external model. The proposed method first uses interferograms generated from SAR Single Look Complex (SLC) images to optimize the parameter adjustments of the external model. Then, the modelled spatial distribution of subsidence is utilized to reduce the fringes of the interferograms generated from the SAR images and to ease the PSI processing. Finally, the ground deformation is retrieved by jointly adding the external model and PSI results. In this paper, fourteen Radarsat-2 SAR images over Fengfeng mining area (China) are used to demonstrate the capabilities of the proposed method. The results are evaluated by comparing them with leveling data of the area covering the same temporal period. Results have shown that, after the optimization, the model is able to mimic the real deformation and the fringes of the interferograms can be effectively reduced. As a consequence, the large gradient deformation then can be better retrieved with the preservation of the nonlinear subsidence term. The ground truth shows that, comparing with the classical PSI and PSI with unadjusted parameters, the proposed scheme reduces the error by 35.2% and 20.4%, respectively.

scholarly journals Long-Term Land Deformation Monitoring Using Quasi-Persistent Scatterer (Q-PS) Technique Observed by Sentinel-1A: Case Study Kelok Sembilan

2019 ◽  
Author(s):  
Pakhrur Razi
Keyword(s):  
High Performance ◽  
Ground Truth ◽  
Deformation Monitoring ◽  
Acquisition Time ◽  
Satellite Orbits ◽  
Mountainous Area ◽  
Ground Truth Data ◽  
Persistent Scatterer ◽  
Land Deformation ◽  
The Impact

Located on the mountainous area, Kelok Sembilan flyover area in West Sumatra, Indonesia has a long history of land deformation, therefore monitoring and analyzing as continuously is a necessity to minimize the impact. Notably, in the rainy season, the land deformation occurs along this area. The zone is crucial as the center of transportation connection in the middle of Sumatra. Quasi-Persistent Scatterer (Q-PS) Interferometry technique was applied for extracting information of land deformation on the field from time to time. Not only does the method have high performance for detecting land deformation but also improve the number of PS point, especially in a non-urban area. This research supported by 90 scenes of Sentinel-1A (C-band) taken from October 2014 to November 2017 for ascending and descending orbit with VV and VH polarization in 5 × 20 m (range × azimuth) resolution. Both satellite orbits detected two critical locations of land deformation namely as zone A and Zone B, which located in positive steep slope where there is more than 500 mm movement in the Line of Sight (LOS) during acquisition time. Deformations in the vertical and horizontal direction for both zone, are 778.9 mm, 795.7 mm and 730.5 mm, 751.7 mm, respectively. Finally, the results were confirmed by ground truth data using Unmanned Aerial Vehicle (UAV) observation.

scholarly journals CHANGE DETECTION BASED ON PERSISTENT SCATTERER INTERFEROMETRY – A NEW METHOD OF MONITORING BUILDING CHANGES

2016 ◽  
Vol III-7 ◽  
pp. 243-250
Author(s):  
C. H. Yang ◽  
B. K. Kenduiywo ◽  
U. Soergel
Keyword(s):  
Time Series ◽  
Change Detection ◽  
Ground Truth ◽  
Google Earth ◽  
Aerial Images ◽  
Radar Signal ◽  
Persistent Scatterer Interferometry ◽  
Small Surface ◽  
Persistent Scatterer ◽  
Main Station

Persistent Scatterer Interferometry (PSI) is a technique to detect a network of extracted persistent scatterer (PS) points which feature temporal phase stability and strong radar signal throughout time-series of SAR images. The small surface deformations on such PS points are estimated. PSI particularly works well in monitoring human settlements because regular substructures of man-made objects give rise to large number of PS points. If such structures and/or substructures substantially alter or even vanish due to big change like construction, their PS points are discarded without additional explorations during standard PSI procedure. Such rejected points are called big change (BC) points. On the other hand, incoherent change detection (ICD) relies on local comparison of multi-temporal images (e.g. image difference, image ratio) to highlight scene modifications of larger size rather than detail level. However, image noise inevitably degrades ICD accuracy. We propose a change detection approach based on PSI to synergize benefits of PSI and ICD. PS points are extracted by PSI procedure. A local change index is introduced to quantify probability of a big change for each point. We propose an automatic thresholding method adopting change index to extract BC points along with a clue of the period they emerge. In the end, PS ad BC points are integrated into a change detection image. Our method is tested at a site located around north of Berlin main station where steady, demolished, and erected building substructures are successfully detected. The results are consistent with ground truth derived from time-series of aerial images provided by Google Earth. In addition, we apply our technique for traffic infrastructure, business district, and sports playground monitoring.

scholarly journals An Application of Persistent Scatterer Interferometry (PSI) Technique for Infrastructure Monitoring

2021 ◽  
Vol 13 (6) ◽  
pp. 1052
Author(s):  
Peppe J. V. D’Aranno ◽  
Alessandro Di Benedetto ◽  
Margherita Fiani ◽  
Maria Marsella ◽  
Ilaria Moriero ◽  
...  
Keyword(s):  
European Space Agency ◽  
Transport Network ◽  
Persistent Scatterer Interferometry ◽  
Space Agency ◽  
Port Area ◽  
Persistent Scatterer ◽  
Area North ◽  
The Stability ◽  
A Site ◽  
Displacement Patterns

In the absence of systematic structural monitoring to support adequate maintenance standards, many existing infrastructures may reach unacceptable quality levels during their life cycle, resulting in significant damage and even potential failure. The metropolitan area of the Gulf of Salerno (Italy), served by a complex multimodal transport network connecting the port area to the roads and railways surrounding the urban area, represents an important industrial and commercial hub at the local and international scale. This particular scenario, developed in a complex morphological and geological context, has led to the interference and overlapping of the transport network (highway, railway, main and secondary roads) that run through the piedmont area north of the port. Given the relevance of the area, our research aims to highlight the capabilities of the persistent scatterer interferometry (PSI) technique, belonging to the group of differential interferometric synthetic aperture radar (SAR), to extract space–temporal series of displacements on ground points or artifacts with millimeter accuracy useful to understand ongoing deformation processes. By using archived data from the European Space Agency missions, i.e., ERS1/2 (European remote-sensing satellite) and ENVISAT (environmental satellite), and the most recent data from COSMO-SkyMed constellations, it was possible to collect a 28-year dataset that was used to spatially analyze displacement patterns at a site-specific scale to check the stability of viaducts and embankments, and on a larger scale to understand the activity of the surrounding slopes. Despite the different resolution and subsequently the ground density, the analysis of the different datasets showed a spatiotemporal consistency in the displacement patterns that concerned two subareas showing significant annual velocity trends, one northeast of the city and the second in the port area. The analysis presented in this paper highlights how a complex geologic area, combining slope movements and various fault systems, could be a major concern for the stability of the overlying infrastructure and also the role that a PSI analysis can play in remotely monitoring their behavior over long periods of time.

Land Subsidence In Jharia Coalfields, Jharkhand, India – Detection, Estimation And Analysis Using Persistent Scatterer Interferometry

2020 ◽  
Author(s):  
Vamshi Krishna Rao Karanam ◽  
Mahdi Motagh ◽  
Kamal Jain
Keyword(s):  
Land Subsidence ◽  
Agricultural Land ◽  
Coal Mines ◽  
Abandoned Mines ◽  
Persistent Scatterer Interferometry ◽  
Mining Areas ◽  
The Past ◽  
Persistent Scatterers ◽  
Persistent Scatterer ◽  
Coal Fires

<p>Subsidence due to coal mining is an increasingly prominent concern in the management of the coalfields. Jharia coalfields, Jharkhand are the oldest and one of the largest coalfields in India. Due to poor management of the coal mines in the past, land subsidence due to coal fires has become a common phenomenon in Jharia. Throughout the year, several factors such as coal fires, seepage of rainwater into mines, and illegal settlements above the abandoned mines contribute to the mining-induced subsidence. Due to such varied causes, subsidence in mining areas is temporally and spatially irregular. Traditional techniques using GPS, leveling, and total station are tedious, time-consuming, and can measure subsidence only on a point basis.</p><p>From the past few years, Interferometric Synthetic Aperture Radar (InSAR) has become a powerful tool to calculate and monitor the land subsidence. Persistent Scatterer Interferometry (PSI) is an advanced time-series interferometry technique, which calculates temporal deformation rates at mm scale with the help of stable pixels in the dataset referred to as Persistent Scatterers. The study aims at the detection and estimation of land subsidence in Jharia coalfield, Jharkhand, India, using the Persistent Scatterer Interferometry (PSI) technique. We used 30 C Band Sentinel-1 SAR images acquired in TOPSAR mode for a period of two years from 2017 to 2019, captured in a descending direction. Data acquired during the dry season are preferred to ensure good coherence. Potential subsidence zones are identified and demarcated using the Differential Interferometry technique in SNAP. PSI analysis is carried out using the StaMPS method. High temporal decorrelation due to the surrounding agricultural land cover and atmospheric interference are significant challenges for the PSI analysis in mining areas. The temporal baseline is adapted accordingly to reduce de-correlation. Atmospheric interference is removed using the TRAIN toolbox using the GACOS correction model. The results show an average subsidence rate in Jharia coal mines of approximately 4 cm/yr. Among the 23 underground mines in Jharia, 6 mines are subsiding at the maximum rate of 12 cm/yr. We identified subsidence in several small coal mines in multiple locations surrounding settlements and agricultural areas that can lead to contamination of groundwater when collapsed. Kustore underground mine covering an area of 1.2 sq. km is the largest subsidence zone in the study area just 200 meters away from the settlements.</p>

scholarly journals CHANGE DETECTION BASED ON PERSISTENT SCATTERER INTERFEROMETRY – A NEW METHOD OF MONITORING BUILDING CHANGES

2016 ◽  
Vol III-7 ◽  
pp. 243-250 ◽  
Author(s):  
C. H. Yang ◽  
B. K. Kenduiywo ◽  
U. Soergel
Keyword(s):  
Time Series ◽  
Change Detection ◽  
Ground Truth ◽  
Google Earth ◽  
Aerial Images ◽  
Radar Signal ◽  
Persistent Scatterer Interferometry ◽  
Small Surface ◽  
Persistent Scatterer ◽  
Main Station

Persistent Scatterer Interferometry (PSI) is a technique to detect a network of extracted persistent scatterer (PS) points which feature temporal phase stability and strong radar signal throughout time-series of SAR images. The small surface deformations on such PS points are estimated. PSI particularly works well in monitoring human settlements because regular substructures of man-made objects give rise to large number of PS points. If such structures and/or substructures substantially alter or even vanish due to big change like construction, their PS points are discarded without additional explorations during standard PSI procedure. Such rejected points are called big change (BC) points. On the other hand, incoherent change detection (ICD) relies on local comparison of multi-temporal images (e.g. image difference, image ratio) to highlight scene modifications of larger size rather than detail level. However, image noise inevitably degrades ICD accuracy. We propose a change detection approach based on PSI to synergize benefits of PSI and ICD. PS points are extracted by PSI procedure. A local change index is introduced to quantify probability of a big change for each point. We propose an automatic thresholding method adopting change index to extract BC points along with a clue of the period they emerge. In the end, PS ad BC points are integrated into a change detection image. Our method is tested at a site located around north of Berlin main station where steady, demolished, and erected building substructures are successfully detected. The results are consistent with ground truth derived from time-series of aerial images provided by Google Earth. In addition, we apply our technique for traffic infrastructure, business district, and sports playground monitoring.

scholarly journals EVALUATION OF A PSI-BASED CHANGE DETECTION REGARDING SIMULATION, COMPARISON, AND APPLICATION

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 1959-1965
Author(s):  
C. H. Yang ◽  
U. Soergel
Keyword(s):  
Change Detection ◽  
Ground Truth ◽  
Coherent Signals ◽  
Persistent Scatterer Interferometry ◽  
Persistent Scatterer ◽  
Deformation Velocity ◽  
Potential Applications ◽  
Pros And Cons ◽  
Coherent Radar ◽  
Occurrence Times

<p><strong>Abstract.</strong> Persistent scatterer interferometry (PSI) detects and analyses strong, stable, and coherent radar signals throughout a time series of SAR images. Such coherent signals are reflected from corner-reflector-like substructures in built-up cities, which are regarded as so-called PS points. Certain PS properties such as deformation velocity and topography height can be derived for scene monitoring. Previously, we introduced a PSI-based change detection to detect disappearing and emerging PS points along with their occurrence times. Such temporary PS points existing only during a certain period correspond to change events, e.g., mostly constructions in cities. The tests using TerraSAR-X images successfully identified where and when the construction events in Berlin took place in 2013. The results were compared and all agreed with the ground truth. In this study, we evaluate our method more deeply. A simulation test is conducted to evaluate the theoretical accuracy in space and time. We also compare our method with two classical approaches: image rationing and amplitude-based semi-PS detection. The computational requirements are revealed afterwards. Finally, potential applications are proposed and discussed. All of these works help us to better characterize our technique and learn the pros and cons.</p>

Recovery boiler sootblowers: History and technological advances

TAPPI Journal ◽  
2015 ◽  
Vol 14 (1) ◽  
pp. 51-60
Author(s):  
HONGHI TRAN ◽  
DANNY TANDRA
Keyword(s):  
Cfd Modeling ◽  
Computing Systems ◽  
The Past ◽  
Technological Advances ◽  
Recovery Boilers ◽  
Computational Fluid Dynamics Cfd ◽  
Recovery Boiler ◽  
Steam Parameters ◽  
Insight Into ◽  
Deposit Removal

Sootblowing technology used in recovery boilers originated from that used in coal-fired boilers. It started with manual cleaning with hand lancing and hand blowing, and evolved slowly into online sootblowing using retractable sootblowers. Since 1991, intensive research and development has focused on sootblowing jet fundamentals and deposit removal in recovery boilers. The results have provided much insight into sootblower jet hydrodynamics, how a sootblower jet interacts with tubes and deposits, and factors influencing its deposit removal efficiency, and have led to two important innovations: fully-expanded sootblower nozzles that are used in virtually all recovery boilers today, and the low pressure sootblowing technology that has been implemented in several new recovery boilers. The availability of powerful computing systems, superfast microprocessors and data acquisition systems, and versatile computational fluid dynamics (CFD) modeling capability in the past two decades has also contributed greatly to the advancement of sootblowing technology. High quality infrared inspection cameras have enabled mills to inspect the deposit buildup conditions in the boiler during operation, and helped identify problems with sootblower lance swinging and superheater platens and boiler bank tube vibrations. As the recovery boiler firing capacity and steam parameters have increased markedly in recent years, sootblowers have become larger and longer, and this can present a challenge in terms of both sootblower design and operation.

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