404 research outputs found
Erratum: Ramses A.M. et al. Vegetation characterization through the use of precipitation-affected SAR signals. Remote sens. 2018, 10, 1647
No full textAfter publication of the research paper [1], the authors wish to make the following correction. The link to the affiliation of Ramon F. Hanssen should have been (1). Hence, the affiliation of Ramon F. Hanssen is Geoscience and Remote Sensing at Delft University of Technology. The authors would like to apologize for any inconvenience caused. The change does not affect the scientific results. The manuscript will be updated and the original will remain online on the article webpage, with a reference to this correction.101
Vegetation Characterization through the Use of Precipitation-Affected SAR Signals
No full textCurrent space-based SAR offers unique opportunities to classify vegetation types and to monitor vegetation growth due to its frequent acquisitions and its sensitivity to vegetation geometry. However, SAR signals also experience frequent temporal fluctuations caused by precipitation events, complicating the mapping and monitoring of vegetation. In this paper, we show that the influence of a priori known precipitation events on the signals can be used advantageously for the classification of vegetation conditions. For this, we exploit the change in Sentinel-1 backscatter response between consecutive acquisitions under varying wetness conditions, which we show is dependent on the state of vegetation. The performance further improves when a priori information on the soil type is taken into account.After publication of the research paper [1], the authors wish to make the following correction. The link to the affiliation of Ramon F. Hanssen should have been (1). Hence, the affiliation of Ramon F. Hanssen is Geoscience and Remote Sensing at Delft University of Technology. The authors would like to apologize for any inconvenience caused. The change does not affect the scientific results. The manuscript will be updated and the original will remain online on the article webpage, with a reference to this correction. Reference 1. Molijn, R.A.; Iannini, L.; López Dekker, P.; Magalhães, P.S.; Hanssen, R.F. Vegetation Characterization through the Use of Precipitation-Affected SAR Signals. Remote Sens. 2018, 10, 1647. [CrossRef]Mathematical Geodesy and PositioningOptical and Laser Remote Sensin
SENTINEL 1: INTERFEROMETRIC APPLICATIONS
No full textHere we report recent applications that extend the range of
feasibility of InSAR: imaging subsurface fluid flow, estimating
flow properties such as permeability, and tracking the integrity
of water defense structures
Data accompanying "Development of an efficient model to calculate subsidence above the Groningen gas field"
No full textThis data package accompanies: Wouters, M.C., Govers, R. & Hanssen, R.F., "Development of an efficient model to calculate subsidence above the
Groningen gas field", submitted to Netherlands Journal of Geosciences.
The data package consist of the workflow described in the accompanying manuscript, and includes the in- and output files of the reported results. An overview of the workflow, and a description of the files contained in the package is provided in README.txt. Instructions for the software installation, including all programs and packages that are required to run the workflow can be found in README_installation.txt. README_figures.txt summarises where to find the plotted data, plotting scripts, and resulting figure files associated with the figures of the manuscript
Dike deformation near Eemshaven and Delfzijl measured with satellite radar interferometry
No full textIt is observed from satellite radar measurements that the dike between Eemshaven and Delfzijl in the north of the Netherlands shows instability. It can be possible that a development of these instability results in dike failure. The two possible failure mechanisms that may occur are settlement and slope-instability. In this research the displacements for different cross sections of the dike were calculated. By analysing the size and the direction of the displacements it is concluded that the dike shows over a length of approximately 110 meters some first indications for the failure mechanism slope-instability. When slope-instability may indeed occur in the future, a slice of soil will slide aside and the dike will fail. This can cause humanitarian and economic consequences. It is therefore necessary to inform the Waterschap Noorderzijlvest who are responsible for the maintenance to the dike.<br/
Data accompanying "Development of an efficient model to calculate subsidence above the Groningen gas field"
No full textThis data package accompanies: Wouters, M.C., Govers, R. & Hanssen, R.F., "Development of an efficient model to calculate subsidence above the
Groningen gas field", submitted to Netherlands Journal of Geosciences.
The data package consist of the workflow described in the accompanying manuscript, and includes the in- and output files of the reported results. An overview of the workflow, and a description of the files contained in the package is provided in README.txt. Instructions for the software installation, including all programs and packages that are required to run the workflow can be found in README_installation.txt. README_figures.txt summarises where to find the plotted data, plotting scripts, and resulting figure files associated with the figures of the manuscript
Estimation of InSAR Tropospheric Delay Using ERA-Interim Global Atmospheric Reanalysis
No full textTropospheric delays are considered to be one of the main performance limitations for Interferometric Synthetic Aperture Radar technology when applied to ground deformation monitoring. In this study, we evaluate the performance of ERA-Interim global atmospheric reanalysis on estimating the tropospheric delay on Sentinel-1 InSAR observations. The results are validated by four D-InSAR interferograms with small temporal/perpendicular baselines computed from Sentinel-1 observations. Based on the study, we concluded that the ERA-Interim global atmospheric reanalysis has relatively better performance in the regions with significant topography and stable atmospheric conditions
Detection of multi-transitional abrupt changes in SAR time series
No full textRepeat-pass acquisitions with coherent Synthetic Aperture Radar (SAR) systems, preserving both phase and amplitude, are more readily available than ever (Bruzzone, 2016). Phase measurements from SAR systems have seen widespread use in the Interferometric Synthetic Aperture (InSAR) technique to measure deformations and elevations since the late 1980’s (Hanssen, 2002). Since the late 1990’s an increase in radar-based change detection is observed, mainly relying on amplitude measurements (Ajadi et al., 2016; Dekker, 1998). The unpredictive multiplicative noise-like speckle, inherent to coherent SAR,makes change detection in SAR imagery difficult (Bamler, 2015). However, the advantages in the all-weather mapping capabilities and object penetrating properties of SAR make it a suitable remote sensing technique for certain applications, such as natural disaster damage assessment (Bruzzone and Prieto, 2000). Broadly speaking, change detection in SAR-based images usually consists of applying an operator on two spatially filtered SAR images to create a difference image (DI), which is then analysed for change points by thresholding and/or clustering (e.g. Alphonse and Biju, 2015). However, such an approach completely neglects the long-term stability of a pixel. When taking the temporal evolution of a pixel into account, the steep increase in data volume puts an emphasis on finding an optimal (’best practice’) approach to the multitemporal change point detection problem. Here it is shown that change point detection methods that properly take the temporal evolution of a pixel into account can provide good segmentation results in multi-temporal SAR data stacks, even in unfiltered stacks that preserve the complete spatial resolution and without considering the spatial context in a pixel’s direct neighbourhood. Moreover, it is found thatmore sophisticated change point detection algorithms don’tnecessarily yield superior segmentation results for various discontinuity functions. This means algorithm selection has to be application driven. The results demonstrate that the suitability of algebraic methods in heterogeneous areas is limited, whereas proper time series analysis yields fairly consistent results over different land covers within the same image. Often, little effort is spend on finding an optimal approach; neglecting data selection and storage, a sensitivity analysis and/or the post-processing analysis procedure, all of which are shown or known to increase the success rate, efficiency and understanding of the segmentation results. It is anticipated that change point detection in SAR imagery will shift away from the classical bi-temporal methodology and multi temporal approaches will become the norm, be it by decomposing multi-temporal stacks or time series analysis.Geoscience and Remote Sensin
Boston University Music Organizations presents The Concert Band and The Percussion Ensemble, April 29, 1992
No full textThis is the concert program of the Boston University Concert Band and Percussion Ensemble performance on Wednesday, April 29, 1992 at 8:00 p.m., at the Tsai Performance Center, 685 Commonwealth Avenue. Works performed were Prelude and Fugue in G Minor by Johann Sebastian Bach (arr. Moehlmann), Childrens March "Over the Hills and Far Away" by Percy Aldridge Grainger, Toccata Without Instruments by Ramon Meyer, Sea Songs by Ralph Vaughan Williams, Toccata by Carlos Chavez, Music for Pieces of Wood by Steve Reich, Lift Off! by Russell Peck, Air by J. S. Bach (arr. Winterbottom), Norwegian March "Valdres" by Johannes Hanssen, Variatios on a Korean Folk Song by John Barnes Chance, and Bugler's Holiday by Leroy Anderson. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund
Konvensjoner om faste kulturminner:: Norges forpliktelser og utfordringer til fagmiljøet
No full textKonvensjoner om faste kulturminner: Norges forpliktelser og utfordringer til fagmiljøet By Françoise Hanssen-Bauer
Since 1961, Norway has ratified seven international conventions on the cultural heritage and its protection. The author presents two of these conventions, the so-called Granada and Malta conventions that Norway ratified in 1996 and 1995 respectively. She focuses her discussion on a few articles in these conventions, and claims that these express a general approach to preservation which implies several challenges and requirements to the concerned professions and communities. She summarizes three emerging dilemmas: - Preserving vs. use and access; - Expert control over decision making vs. participation of the public; - Developing national professional traditions vs. European collaboration and coordination 
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