Centre de documentation
scientifique

Computation of random errors in digital terrain models / J. Bjorke in Geoinformatica, vol 11 n° 3 (September - November 2007)  

Public [article]  inGeoinformatica > vol 11 n° 3 (September - November 2007) . - pp 359 - 382 Titre : Computation of random errors in digital terrain models Type de document : Article/Communication Auteurs : J. Bjorke, Auteur ; S. Nilsen, Auteur Année de publication : 2007 Article en page(s) : pp 359 - 382 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] analyse comparative [Termes IGN] erreur aléatoire [Termes IGN] filtrage du bruit [Termes IGN] géostatistique [Termes IGN] modèle numérique de terrain [Termes IGN] rééchantillonnage [Termes IGN] sondeur multifaisceaux [Termes IGN] Triangulated Irregular Network [Termes IGN] variogramme Résumé : (Auteur) Geostatistical methods make it possible to estimate the random errors in digital terrain models (DTMs) from one single set of measurements. After average interpolating trend removal, the error is derived from the variogram of the residual data set. This method is compared with a procedure that uses triangulation and resampling of two overlapping DTMs for extracting the error component. Eighteen small areas measured with a multibeam echo sounder are selected for the comparison. In the experiment the two methods come out with similar values for the random error. A by-product of the experiment is the development of a model for the average noise reduction caused by resampling of triangle models (TINs). The method we apply for the trend computation has time complexity O(n). Since the noise computation only requires the part of the variogram close to the origin, it is possible to formulate the computation of the random error in DTMs in O(n) time. Copyright Springer Numéro de notice : A2007-381 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1007/s10707-006-0012-x En ligne : https://doi.org/10.1007/s10707-006-0012-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28744 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-07031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Examination of a constant-area quadrilateral grid in representation of global digital elevation models / J.T. Bjorke in International journal of geographical information science IJGIS, vol 18 n° 7 (november 2004)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 7 (november 2004) . - pp 653 - 664 Titre : Examination of a constant-area quadrilateral grid in representation of global digital elevation models Type de document : Article/Communication Auteurs : J.T. Bjorke, Auteur ; S. Nilsen, Auteur Année de publication : 2004 Article en page(s) : pp 653 - 664 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Projections [Termes IGN] arbre quadratique [Termes IGN] calcul d'erreur [Termes IGN] maille carrée [Termes IGN] modèle numérique de surface [Termes IGN] ondelette [Termes IGN] quadrant [Termes IGN] World Geodetic System 1984 Résumé : (Auteur) The WGS84 ellipsoid is tessellated using quadrilaterals of roughly the same size. This tiling is of general interest to global geographical information systems, but it has special relevance to global digital elevation models based on block averages. The simple relation between the tiling presented and the latitude/longitude reference system makes the tiling easy to implement, and the quadrilateral property of the cells offers regular subdivision like quadtrees. An error analysis gives a strict bound on the difference between cell averages calculated in plane and ellipsoidal coordinates. The mathematical results from this investigation are general and can be applied in error analysis related to other types of quadrilateral meshes. The grid can be easily subdivided into quadtree blocks. The error estimate makes it possible to combine the quadtree structure with standard two-dimensional wavelet representations. Numéro de notice : A2004-395 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/POSITIONNEMENT Nature : Article DOI : 10.1080/13658810410001705334 En ligne : https://doi.org/10.1080/13658810410001705334 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26922 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-04071	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-04072	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Wavelets applied to simplification of digital terrain models / J.T. Bjorke in International journal of geographical information science IJGIS, vol 17 n° 7 (october 2003)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 17 n° 7 (october 2003) . - pp 601 - 621 Titre : Wavelets applied to simplification of digital terrain models Type de document : Article/Communication Auteurs : J.T. Bjorke, Auteur ; S. Nilsen, Auteur Année de publication : 2003 Article en page(s) : pp 601 - 621 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] filtrage non linéaire [Termes IGN] filtrage numérique d'image [Termes IGN] modèle numérique de terrain [Termes IGN] ondelette [Termes IGN] seuillage d'image Résumé : (Auteur) Wavelet thresholding is used to generate simplified terrain models. This nonlinear filtering technique is adaptive in the sense that the large wavelet coefficients in areas of high relief are kept, whereas all coefficients smaller than a threshold value, representing smooth areas, are thrown away. The degree of detail in the simplified model is controlled by the number of wavelet coefficients retained. Two different areas are analysed using this method. The experiments show the smoothing effect of the thresholding, and how the main terrain features survive as the threshold value increases. At large threshold values the method introduces blocking artifacts in the model. Numéro de notice : A2003-256 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/1365881031000135500 En ligne : https://doi.org/10.1080/1365881031000135500 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22551 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-03071	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-03072	RAB	Revue	Centre de documentation	En réserve L003	Disponible