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Recognition of crevasses with high-resolution digital elevation models: Application of geomorphometric modeling and texture analysis / Olga T. Ishalina in Transactions in GIS, vol 25 n° 5 (October 2021)  

Public [article]  inTransactions in GIS > vol 25 n° 5 (October 2021) . - pp 2529 - 2552 Titre : Recognition of crevasses with high-resolution digital elevation models: Application of geomorphometric modeling and texture analysis Type de document : Article/Communication Auteurs : Olga T. Ishalina, Auteur ; Dimitri P. Bliakharskii, Auteur ; Igor V. Florinsky, Auteur Année de publication : 2021 Article en page(s) : pp 2529 - 2552 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse comparative [Termes IGN] analyse texturale [Termes IGN] Antarctique [Termes IGN] crevasse [Termes IGN] glacier [Termes IGN] image à haute résolution [Termes IGN] image captée par drone [Termes IGN] modèle numérique de surface [Termes IGN] texture d'image Résumé : (auteur) Crevasses—cracks in glaciers and ice sheets—pose a danger to polar researchers and glaciologists. We compare the capabilities of two techniques—geomorphometric modeling and texture analysis—to recognize open and hidden crevasses using high-resolution digital elevation models (DEMs) generated from images collected by an unmanned aerial system (UAS). The first technique includes derivation of local morphometric variables; the second includes calculation of the Haralick texture features. The study area is represented by the first 30 km of a sledge route between the Progress and Vostok polar stations, East Antarctica. The UAS survey was performed by a Geoscan 201 Geodesy UAS. For the sledge route area, DEMs with resolutions of 0.25, 0.5, and 1 m were generated. Models of 12 morphometric variables and 11 texture features were derived from the DEMs. In terms of crevasse recognition, the most informative morphometric variable and texture feature was horizontal curvature and inverse difference moment, respectively. In most cases, derivation and mapping of these variables allow one to recognize crevasses wider than 3 m; narrower crevasses can be recognized for lengths from 500 m. For crevasse recognition, the geomorphometric modeling and the Haralick texture analysis can complement each other. Numéro de notice : A2021-122 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/tgis.12790 Date de publication en ligne : 06/07/2021 En ligne : https://doi.org/10.1111/tgis.12790 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99303 [article]

Computation of the third-order partial derivatives from a digital elevation model / Igor V. Florinsky in International journal of geographical information science IJGIS, vol 23 n° 1-2 (january 2009)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 23 n° 1-2 (january 2009) . - pp 213 - 231 Titre : Computation of the third-order partial derivatives from a digital elevation model Type de document : Article/Communication Auteurs : Igor V. Florinsky, Auteur Année de publication : 2009 Article en page(s) : pp 213 - 231 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] filtrage du bruit [Termes IGN] modèle numérique de surface [Termes IGN] réseau de drainage Résumé : (Auteur) Loci of extreme curvature of the topographic surface may be defined by the derivation function (T) depending on the first-, second-, and third-order partial derivatives of elevation. The loci may partially describe ridge and thalweg lines. The first- and second-order partial derivatives are commonly calculated from a digital elevation model (DEM) by fitting the second-order polynomial to a 3times3 window. This approach cannot be used to compute the third-order partial derivatives and T. We deduced formulae to estimate the first-, second-, and third-order partial derivatives from a DEM fitting the third-order polynomial to a 5times5 window. The polynomial is approximated to elevation values of the window. This leads to a local denoising that may enhance calculations. Under the same grid size of a DEM and root mean square error (RMSE) of elevation, calculation of the second-order partial derivatives by the method developed results in significantly lower RMSE of the derivatives than that using the second-order polynomial and the 3times3 window. An RMSE expression for the derivation function is deduced. The method proposed can be applied to derive any local topographic variable, such as slope gradient, aspect, curvatures, and T. Treatment of a DEM by the method developed demonstrated that T mapping may not substitute regional logistic algorithms to detect ridge/thalweg networks. However, the third-order partial derivatives of elevation can be used in digital terrain analysis, particularly, in landform classifications. Copyright Taylor & Francis Numéro de notice : A2009-134 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810802527499 En ligne : https://doi.org/10.1080/13658810802527499 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29764 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-09011	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-09012	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Errors of signal processing in digital terrain modelling / Igor V. Florinsky in International journal of geographical information science IJGIS, vol 16 n° 5 (july 2002)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 16 n° 5 (july 2002) . - pp 475 - 501 Titre : Errors of signal processing in digital terrain modelling Type de document : Article/Communication Auteurs : Igor V. Florinsky, Auteur Année de publication : 2002 Article en page(s) : pp 475 - 501 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] erreur de rendu [Termes IGN] modèle numérique de terrain [Termes IGN] phénomène de Gibbs [Termes IGN] propagation du signal [Termes IGN] traitement du signal Résumé : (Auteur) We present new interpretation of three classes of errors in digital terrain models (DTMs) which can be sources of artefacts in DTM-based studies: (a) errors in interpolation of digital elevation models (DEMs) caused by the Gibbs phenomenon; (b) errors in DTM derivation from DEMs with'enhanced' resolution due to noise increase after DEM differentiation; (c) errors in DTM derivation caused by displacement of a DEM grid. Explanation of artefact roots and ways to avoid them are carried out in the context of the theory of signal processing. The Gibbs phenomenon is a specific behaviour of some functions manifested as over- and undershoots near a jump discontinuity. Any DEM includes jump discontinuities of the elevation, such as escarpments and pronounced errors of DEM generation. There are four main ways to prevent or reduce DEM errors caused by the Gibbs phenomenon: (a) decreasing the jump discontinuity before DEM interpolation; (b) using interpolation functions which do not generate the Gibbs phenomenon; (c) omitting over- and undershoots after DEM interpolation; (d) filtering the Gibbs phenomenon. Derivation of topographic variables from DEMs marked by 'enhanced' resolution can lead to artefacts. If a DEM of this kind is interpolated by triangul ati on -based algorithms, triangular patterns may be revealed on maps of topographic variables. If an 'enhanced' resolution of DEM is achieved by the weighted average methods of interpolation, contour 'traces' may be seen on maps. This is because partial derivatives used to calculate some topographic variables are very responsive to high-frequency components of a DEM. To prevent these errors one should use a regular DEM with a grid space relating to an average distance between points in an irregular DEM. Displacement of a grid of points, wherein elevation values are interpolated or determined, influences the derivation of topographic variables (e.g. map design of horizontal and vertical curvatures). Some patterns break, merge, and change their width and length. Small dots, lines, and particles of big patterns can appear and disappear on maps. These effects should be taken into account in the application of these maps to DTM-based geological studies. Numéro de notice : A2002-150 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : 10.1080/13658810210129139 En ligne : https://doi.org/10.1080/13658810210129139 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22065 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-02051	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Determination of grid size for digital terrain modelling in landscape investigations: exemplified by soil moisture distribution at a micro-scale / Igor V. Florinsky in International journal of geographical information science IJGIS, vol 14 n° 8 (december 2000)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 14 n° 8 (december 2000) . - pp 815 - 832 Titre : Determination of grid size for digital terrain modelling in landscape investigations: exemplified by soil moisture distribution at a micro-scale Type de document : Article/Communication Auteurs : Igor V. Florinsky, Auteur ; G.A. Kuryakova, Auteur Année de publication : 2000 Article en page(s) : pp 815 - 832 Note générale : Bibliographie 2 pages Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie [Termes IGN] distribution spatiale [Termes IGN] humidité du sol [Termes IGN] maille triangulaire [Termes IGN] modèle numérique de terrain Numéro de notice : A2000-178 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/136588100750022804 En ligne : https://doi.org/10.1080/136588100750022804 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21594 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-00081	RAB	Revue	Centre de documentation	En réserve L003	Disponible