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Photogrammetric Bathymetry for the Canadian Arctic / Matus Hodul in Marine geodesy, Vol 43 n° 1 (January 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 1 (January 2020) . - pp 23 - 43 Titre : Photogrammetric Bathymetry for the Canadian Arctic Type de document : Article/Communication Auteurs : Matus Hodul, Auteur ; René Chénier, Auteur ; Marc-André Faucher, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 23 - 43 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bathymétrie [Termes IGN] Arctique, océan [Termes IGN] Canada [Termes IGN] carte marine [Termes IGN] données hydrographiques [Termes IGN] fond marin [Termes IGN] image Worldview [Termes IGN] télédétection spatiale Résumé : (auteur) Remote sensing is becoming common in the estimation of bathymetry for navigational charting through a process known as Satellite Derived Bathymetry (SDB). Most SDB techniques currently used by hydrographic offices employ an empirical approach, requiring the use of in-situ data to calibrate a relationship between spectral information and coincident depths. This article reports on a multi-site test of an alternative SDB method which uses photogrammetry to extract depths from stereo WorldView-2 imagery. In areas with heterogeneous seafloors, the empirical approach faces difficulties in establishing the relationship between colour and depth, while the photogrammetric approach uses the contrasting seafloor features for triangulation. Additionally, the photogrammetric method may be applied in areas lacking previous survey data. Five study areas in Nunavut, Canada were selected to test the robustness of the method in different environments and under different imaging conditions. Study areas were (with resulting RMSE/Bias given in metres) Coral Harbour (0.84/−0.47), Cambridge Bay (1.16/−0.15), Queen Maud Gulf (0.97/0.06), Arviat (0.99/−0.009), and Frobisher Bay, where extraction largely failed due to environmental conditions. Accuracies demonstrated here are similar to those seen using the empirical approach, suggesting that these two methods may be used in conjunction, each applied to regions where they are better suited. Numéro de notice : A2020-052 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/01490419.2019.1685030 Date de publication en ligne : 22/11/2019 En ligne : https://doi.org/10.1080/01490419.2019.1685030 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94920 [article]

Applying iterative method to solving high-order terms of seafloor topography / Diao Fan in Marine geodesy, Vol 43 n° 1 (January 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 1 (January 2020) . - pp 63 - 85 Titre : Applying iterative method to solving high-order terms of seafloor topography Type de document : Article/Communication Auteurs : Diao Fan, Auteur ; Shanshan Li, Auteur ; Shuyu Meng, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 63 - 85 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie [Termes IGN] Chine, mer de [Termes IGN] fond marin [Termes IGN] force de gravitation [Termes IGN] gravimétrie en mer [Termes IGN] inversion [Termes IGN] itération [Termes IGN] relief sous-marin Résumé : (auteur) We introduce an iterative inversion method to address the problems in high-order seafloor topography inversion using gravity data (gravity anomaly and vertical gravity gradient anomaly), such as the difficulty in computing the equation and the uniqueness of the calculation results. A part of the South China Sea is selected as the experimental area. Considering the coherence and admittance function of gravity topography and vertical gravity gradient topography, the inversion band of the gravity anomaly and vertical gravity gradient anomaly in the study area is 30 km–120 km. Seafloor topography models of different orders are constructed using an iterative method, and the performance of each seafloor topography model is analyzed against ETOPO1 and other seafloor topography models. The experimental results show that as the inversion order increases, the clarity and richness of seafloor topographic expression continuously improve. However, the accuracy of seafloor topography inversion does not improve significantly when the inversion order exceeds a certain value, which is related to the contribution of high-order seafloor topography to gravity information. The results show that the accuracy of BGT4 (inversion model constructed by the gravity anomaly) is slightly poorer than that of BVGGT4 (inversion model constructed by the vertical gravity gradient anomaly) in areas with complex topography, such as multi-seamounts and trenches, and the results are generally better in areas with flat seafloor topography. Numéro de notice : A2020-463 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2019.1670298 Date de publication en ligne : 08/10/2019 En ligne : https://doi.org/10.1080/01490419.2019.1670298 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95125 [article]