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Exploring the sensitivity of coastal inundation modelling to DEM vertical error / Harry West in International journal of geographical information science IJGIS, vol 32 n° 5-6 (May - June 2018)
[article]
Titre : Exploring the sensitivity of coastal inundation modelling to DEM vertical error Type de document : Article/Communication Auteurs : Harry West, Auteur ; Michael Horswell, Auteur ; Nevil Quinn, Auteur Année de publication : 2018 Article en page(s) : pp 1172 - 1193 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] analyse de sensibilité
[Termes IGN] erreur en altitude
[Termes IGN] estuaire
[Termes IGN] incertitude géométrique
[Termes IGN] inondation
[Termes IGN] littoral
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] modèle numérique de surface
[Termes IGN] montée du niveau de la mer
[Termes IGN] Royaume-UniRésumé : (Auteur) As sea level is projected to rise throughout the twenty-first century due to climate change, there is a need to ensure that sea level rise (SLR) models accurately and defensibly represent future flood inundation levels to allow for effective coastal zone management. Digital elevation models (DEMs) are integral to SLR modelling, but are subject to error, including in their vertical resolution. Error in DEMs leads to uncertainty in the output of SLR inundation models, which if not considered, may result in poor coastal management decisions. However, DEM error is not usually described in detail by DEM suppliers; commonly only the RMSE is reported. This research explores the impact of stated vertical error in delineating zones of inundation in two locations along the Devon, United Kingdom, coastline (Exe and Otter Estuaries). We explore the consequences of needing to make assumptions about the distribution of error in the absence of detailed error data using a 1 m, publically available composite DEM with a maximum RMSE of 0.15 m, typical of recent LiDAR-derived DEMs. We compare uncertainty using two methods (i) the NOAA inundation uncertainty mapping method which assumes a normal distribution of error and (ii) a hydrologically correct bathtub method where the DEM is uniformly perturbed between the upper and lower bounds of a 95% linear error in 500 Monte Carlo Simulations (HBM+MCS). The NOAA method produced a broader zone of uncertainty (an increase of 134.9% on the HBM+MCS method), which is particularly evident in the flatter topography of the upper estuaries. The HBM+MCS method generates a narrower band of uncertainty for these flatter areas, but very similar extents where shorelines are steeper. The differences in inundation extents produced by the methods relate to a number of underpinning assumptions, and particularly, how the stated RMSE is interpreted and used to represent error in a practical sense. Unlike the NOAA method, the HBM+MCS model is computationally intensive, depending on the areas under consideration and the number of iterations. We therefore used the HBM+ MCS method to derive a regression relationship between elevation and inundation probability for the Exe Estuary. We then apply this to the adjacent Otter Estuary and show that it can defensibly reproduce zones of inundation uncertainty, avoiding the computationally intensive step of the HBM+MCS. The equation-derived zone of uncertainty was 112.1% larger than the HBM+MCS method, compared to the NOAA method which produced an uncertain area 423.9% larger. Each approach has advantages and disadvantages and requires value judgements to be made. Their use underscores the need for transparency in assumptions and communications of outputs. We urge DEM publishers to move beyond provision of a generalised RMSE and provide more detailed estimates of spatial error and complete metadata, including locations of ground control points and associated land cover. Numéro de notice : A2018-203 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2018.1444165 Date de publication en ligne : 14/03/2018 En ligne : https://doi.org/10.1080/13658816.2018.1444165 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89874
in International journal of geographical information science IJGIS > vol 32 n° 5-6 (May - June 2018) . - pp 1172 - 1193[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 079-2018031 RAB Revue Centre de documentation En réserve L003 Disponible On the topographic bias and density distribution in modelling the geoid and orthometric heights / Lars E. Sjöberg in Journal of geodetic science, vol 8 n° 1 (January 2018)
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Titre : On the topographic bias and density distribution in modelling the geoid and orthometric heights Type de document : Article/Communication Auteurs : Lars E. Sjöberg, Auteur Année de publication : 2018 Article en page(s) : pp 30 - 33 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude orthométrique
[Termes IGN] analyse numérique
[Termes IGN] erreur systématique
[Termes IGN] géoïde
[Termes IGN] incertitude géométrique
[Termes IGN] montagneRésumé : (Auteur) It is well known that the success in precise determinations of the gravimetric geoid height (N) and the orthometric height (H) rely on the knowledge of the topographic mass distribution. We show that the residual topographic bias due to an imprecise information on the topographic density is practically the same for N and H, but with opposite signs. This result is demonstrated both for the Helmert orthometric height and for a more precise orthometric height derived by analytical continuation of the external geopotential to the geoid. This result leads to the conclusion that precise gravimetric geoid heights cannot be validated by GNSS-levelling geoid heights in mountainous regions for the errors caused by the incorrect modelling of the topographic mass distribution, because this uncertainty is hidden in the difference between the two geoid estimators. Numéro de notice : A2018-614 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jogs-2018-0004 Date de publication en ligne : 02/03/2018 En ligne : https://doi.org/10.1515/jogs-2018-0004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92662
in Journal of geodetic science > vol 8 n° 1 (January 2018) . - pp 30 - 33[article]An iterative method for obtaining a mean 3D axis from a set of GNSS traces for use in positional controls / A. Mozas-Calvache in Survey review, vol 49 n° 355 (October 2017)
[article]
Titre : An iterative method for obtaining a mean 3D axis from a set of GNSS traces for use in positional controls Type de document : Article/Communication Auteurs : A. Mozas-Calvache, Auteur ; Francisco Javier Ariza-López, Auteur Année de publication : 2017 Article en page(s) : pp 277 - 284 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique
[Termes IGN] axe médian
[Termes IGN] classification par nuées dynamiques
[Termes IGN] exploration de données géographiques
[Termes IGN] incertitude géométrique
[Termes IGN] itération
[Termes IGN] précision de localisation
[Termes IGN] trace GPS
[Termes IGN] traitement de données localiséesRésumé : (Auteur) This paper describes a new method of data mining for determining a 3D mean axis from a set of surveyed Global Navigation Satellite Systems traces. The purpose is to obtain a mean axis and its uncertainty in order for them to be used in line-based positional controls. The method is based on an iterative process of condensation. The final mean axis is selected when a determined level of accuracy is achieved. So the method provides a relative positional accuracy value of the final solution. The example developed in this study demonstrates the viability of this method and allows analysis of the initial size of the set needed in order to achieve a final accuracy. Using real data, the proposed methodology has also been compared with the K-means methodology in order to analyse its advantages and conditions of use. The results have demonstrated an improvement in accuracy and geometrical definition of the axis obtained. Numéro de notice : A2017-551 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1171956 En ligne : https://doi.org/10.1080/00396265.2016.1171956 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86612
in Survey review > vol 49 n° 355 (October 2017) . - pp 277 - 284[article]Height uncertainty in digital terrain modelling with unmanned aircraft systems / Stig-Göran Mårtensson in Survey review, vol 49 n° 355 (October 2017)
[article]
Titre : Height uncertainty in digital terrain modelling with unmanned aircraft systems Type de document : Article/Communication Auteurs : Stig-Göran Mårtensson, Auteur ; Yuriy Reshetyuk, Auteur Année de publication : 2017 Article en page(s) : pp 312 - 318 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] Agisoft Photoscan
[Termes IGN] altitude
[Termes IGN] drone
[Termes IGN] incertitude géométrique
[Termes IGN] modèle numérique de surface
[Termes IGN] modèle numérique de terrain
[Termes IGN] surface imperméableRésumé : (Auteur) The purpose of this paper is to investigate the height uncertainty of digital terrain models (DTMs) generated from unmanned aircraft system (UAS) surveys over different surface types – asphalt, gravel and grass. The data used in the study was acquired during two UAS flights performed in spring 2014 with a fixed wing aircraft and two different cameras, from the flying height of about 100 m, and it was processed in different software suites – Agisoft PhotoScan, RapidStation and RapidTerrain. The results show that it is possible to achieve the height uncertainty (expressed as a Root Mean Square Error) in a DTM of below 0.02 m on asphalt surfaces and below 0.04 m on gravel and grass surfaces, provided an overcast sky. Numéro de notice : A2017-554 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/00396265.2016.1180754 En ligne : http://dx.doi.org/10.1080/00396265.2016.1180754 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86615
in Survey review > vol 49 n° 355 (October 2017) . - pp 312 - 318[article]The geometry of space-time prisms with uncertain anchors / Bart Kuijpers in International journal of geographical information science IJGIS, vol 31 n° 9-10 (September - October 2017)
[article]
Titre : The geometry of space-time prisms with uncertain anchors Type de document : Article/Communication Auteurs : Bart Kuijpers, Auteur ; Walied Othman, Auteur Année de publication : 2017 Article en page(s) : pp 1722 - 1748 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] analyse spatio-temporelle
[Termes IGN] données spatiotemporelles
[Termes IGN] erreur de mesure
[Termes IGN] géométrie
[Termes IGN] incertitude géométrique
[Termes IGN] modèle conceptuel de données spatio-temporelles
[Termes IGN] objet mobile
[Termes IGN] prisme spatio-temporel
[Termes IGN] Time-geography
[Termes IGN] zone d'intérêtRésumé : (Auteur) Space-time prisms envelop all spatio-temporal locations that moving objects may have visited between two of their known spatio-temporal locations, given a bound on their travel speed. In this context, the known locations are often the result of observations or measurements, and they are called ‘anchor points’. The classic space-time prism, in isotropic two-dimensional space, as well as in transportation networks, assumes that the measurements of these anchor points are exact. Whereas, in many applications, we can assume that time can be measured fairly precisely, this assumption is unrealistic for the spatial components of measured locations (we think of Global Positioning System (GPS) errors, for instance). In this paper, we extend the classical prism from anchor points to circular ‘anchor regions’ that capture the uncertainty or error on their measurement. We define the notion of a space-time prism with uncertain anchor points, called uncertain prism, for short. We study the geometry of uncertain prisms in an arbitrary metric space to make this concept as widely applicable as possible. We also focus on the rims of uncertain space-time prisms, which demarcate the area that a moving object can have visited between two anchor regions (given some local speed limitations). Numéro de notice : A2017-504 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2017.1319950 En ligne : https://doi.org/10.1080/13658816.2017.1319950 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86449
in International journal of geographical information science IJGIS > vol 31 n° 9-10 (September - October 2017) . - pp 1722 - 1748[article]Réservation
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