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Testing deformation hypotheses by constraints on a time series of geodetic observations / Hiddo Velsink in Journal of applied geodesy, vol 12 n° 1 (January 2018)  

Public [article]  inJournal of applied geodesy > vol 12 n° 1 (January 2018) . - pp 77 - 94 Titre : Testing deformation hypotheses by constraints on a time series of geodetic observations Type de document : Article/Communication Auteurs : Hiddo Velsink, Auteur Année de publication : 2018 Article en page(s) : pp 77 - 94 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] compensation par moindres carrés [Termes IGN] congruence [Termes IGN] déformation géométrique [Termes IGN] programmation par contraintes [Termes IGN] série temporelle Résumé : (auteur) In geodetic deformation analysis observations are used to identify form and size changes of a geodetic network, representing objects on the earth’s surface. The network points are monitored, often continuously, because of suspected deformations. A deformation may affect many points during many epochs. The problem is that the best description of the deformation is, in general, unknown. To find it, different hypothesised deformation models have to be tested systematically for agreement with the observations. The tests have to be capable of stating with a certain probability the size of detectable deformations, and to be datum invariant. A statistical criterion is needed to find the best deformation model. Existing methods do not fulfil these requirements. Here we propose a method that formulates the different hypotheses as sets of constraints on the parameters of a least-squares adjustment model. The constraints can relate to subsets of epochs and to subsets of points, thus combining time series analysis and congruence model analysis. The constraints are formulated as nonstochastic observations in an adjustment model of observation equations. This gives an easy way to test the constraints and to get a quality description. The proposed method aims at providing a good discriminating method to find the best description of a deformation. The method is expected to improve the quality of geodetic deformation analysis. We demonstrate the method with an elaborate example. Numéro de notice : A2018-016 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2017-0028 En ligne : https://doi.org/10.1515/jag-2017-0028 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89095 [article]

Time series analysis of 3D coordinates using nonstochastic observations / Hiddo Velsink in Journal of applied geodesy, vol 10 n° 1 (March 2016)  

Public [article]  inJournal of applied geodesy > vol 10 n° 1 (March 2016) . - pp 5 - 16 Titre : Time series analysis of 3D coordinates using nonstochastic observations Type de document : Article/Communication Auteurs : Hiddo Velsink, Auteur Année de publication : 2016 Article en page(s) : pp 5 - 16 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] compensation de coordonnées [Termes IGN] coordonnées cartésiennes [Termes IGN] déformation géométrique [Termes IGN] matrice de covariance [Termes IGN] série temporelle [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) Adjustment and testing of a combination of stochastic and nonstochastic observations is applied to the deformation analysis of a time series of 3D coordinates. Nonstochastic observations are constant values that are treated as if they were observations. They are used to formulate constraints on the unknown parameters of the adjustment problem. Thus they describe deformation patterns. If deformation is absent, the epochs of the time series are supposed to be related via affine, similarity or congruence transformations. S-basis invariant testing of deformation patterns is treated. The model is experimentally validated by showing the procedure for a point set of 3D coordinates, determined from total station measurements during five epochs. The modelling of two patterns, the movement of just one point in several epochs, and of several points, is shown. Full, rank deficient covariance matrices of the 3D coordinates, resulting from free network adjustments of the total station measurements of each epoch, are used in the analysis. Numéro de notice : A2016-549 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2015-0027 En ligne : http://dx.doi.org/10.1515/jag-2015-0027 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81693 [article]

Extendable linearised adjustment model for deformation analysis / Hiddo Velsink in Survey review, vol 47 n° 345 (November 2015)  

Public [article]  inSurvey review > vol 47 n° 345 (November 2015) . - pp 397 - 410 Titre : Extendable linearised adjustment model for deformation analysis Type de document : Article/Communication Auteurs : Hiddo Velsink, Auteur Année de publication : 2015 Article en page(s) : pp 397 - 410 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie moderne [Termes IGN] ajustement de paramètres [Termes IGN] analyse diachronique [Termes IGN] congruence [Termes IGN] matrice de covariance [Termes IGN] surveillance d'ouvrage [Termes IGN] tachéomètre électronique [Termes IGN] transformation affine Résumé : (auteur) This paper gives a linearised adjustment model for the affine, similarity and congruence transformations in 3D that is easily extendable with other parameters to describe deformations. The model considers all coordinates stochastic. Full positive semi-definite covariance matrices and correlation between epochs can be handled. The determination of transformation parameters between two or more coordinate sets, determined by geodetic monitoring measurements, can be handled as a least squares adjustment problem. It can be solved without linearisation of the functional model, if it concerns an affine, similarity or congruence transformation in one-, two- or three-dimensional space. If the functional model describes more than such a transformation, it is hardly ever possible to find a direct solution for the transformation parameters. Linearisation of the functional model and applying least squares formulas is then an appropriate mode of working. The adjustment model is given as a model of observation equations with constraints on the parameters. The starting point is the affine transformation, whose parameters are constrained to get the parameters of the similarity or congruence transformation. In this way the use of Euler angles is avoided. Because the model is linearised, iteration is necessary to get the final solution. In each iteration step approximate coordinates are necessary that fulfil the constraints. For the affine transformation it is easy to get approximate coordinates. For the similarity and congruence transformation the approximate coordinates have to comply to constraints. To achieve this, use is made of the singular value decomposition of the rotation matrix. To show the effectiveness of the proposed adjustment model total station measurements in two epochs of monitored buildings are analysed. Coordinate sets with full, rank deficient covariance matrices are determined from the measurements and adjusted with the proposed model. Testing the adjustment for deformations results in detection of the simulated deformations. Numéro de notice : A2015-946 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270614Y.0000000140 En ligne : https://doi.org/10.1179/1752270614Y.0000000140 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79650 [article]

On the deformation analysis of point fields / Hiddo Velsink in Journal of geodesy, vol 89 n° 11 (november 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 11 (november 2015) . - pp 1071-1087 Titre : On the deformation analysis of point fields Type de document : Article/Communication Auteurs : Hiddo Velsink, Auteur Année de publication : 2015 Article en page(s) : pp 1071-1087 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] analyse diachronique [Termes IGN] déformation de la croute terrestre [Termes IGN] ellipsoïde (géodésie) [Termes IGN] méthode des moindres carrés Résumé : (auteur) A new approach to determine a multi-point deformation of the earth’s surface or objects upon it, represented by point fields measured in two epochs, is presented. The problem of determining, which points have been deformed, is not approached by testing point-by-point, but by formulating alternative hypotheses that test if one, two or more subsets of points have been deformed, each subset in its own way. The method is based on the least squares connection adjustment, defines alternative hypotheses and searches the best one by testing a large amount of them. If the best hypothesis is found, a least squares estimation of the deformations is provided. The test results of the presented method are invariant under changes of the S-systems in which the point coordinates are defined. The results of a numerical test of the method applied to a simulated network are given. In designing a geodetic deformation network minimal detectable deformations can be computed, belonging to likely deformation patterns. The proposed method leads to a reconsideration of the duality of reference and object points. A comparison with the method of testing confidence ellipsoids is made. The relevance of the difference between geometric and physical interpretations of deformations and the consequences of the presented method for future developments are discussed. Numéro de notice : A2015-883 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0835-z En ligne : https://doi.org/10.1007/s00190-015-0835-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79422 [article]