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Accuracy of unmodified Stokes’ integration in the R-C-R procedure for geoid computation / Zahra Ismaïl in Journal of applied geodesy, vol 9 n° 2 (June 2015)  

Public [article]  inJournal of applied geodesy > vol 9 n° 2 (June 2015) . - pp 112 - 122 Titre : Accuracy of unmodified Stokes’ integration in the R-C-R procedure for geoid computation Type de document : Article/Communication Auteurs : Zahra Ismaïl, Auteur ; Olivier Jamet , Auteur Année de publication : 2015 Projets : 3-projet - voir note / Article en page(s) : pp 112 - 122 Note générale : bibliographie This work was supported by a doctoral scholarship from the University of Tichrine, Latakia, Syria. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altitude [Termes IGN] anomalie de pesanteur [Termes IGN] Earth Gravity Model 2008 [Termes IGN] géoïde [Termes IGN] GravSoft [Termes IGN] harmonique sphérique [Termes IGN] intégrale de Stokes [Termes IGN] montagne Résumé : (auteur) Geoid determinations by the Remove-Compute-­Restore (R-C-R) technique involves the application of Stokes’ integral on reduced gravity anomalies. Numerical Stokes’ integration produces an error depending on the choice of the integration radius, grid resolution and Stokes’ kernel function. In this work, we aim to evaluate the accuracy of Stokes’ integral through a study on synthetic gravitational signals derived from EGM2008 on three different landscape areas with respect to the size of the integration domain and the resolution of the anomaly grid. The influence of the integration radius was studied earlier by several authors. Using real data, they found that the choice of relatively small radii (less than 1°) enables to reach an optimal accuracy. We observe a general behaviour coherent with these earlier studies. On the other hand, we notice that increasing the integration radius up to 2° or 2.5° might bring significantly better results. We note that, unlike the smallest radius corresponding to a local minimum of the error curve, the optimal radius in the range 0° to 6° depends on the terrain characteristics. We also find that the high frequencies, from degree 600, improve continuously with the integration radius in both semi-­mountainous and mountain areas. Finally, we note that the relative error of the computed geoid heights depends weakly on the anomaly spherical harmonic degree in the range from degree 200 to 2000. It remains greater than 10 % for any integration radii up to 6°. This result tends to prove that a one centimetre accuracy cannot be reached in semi-mountainous and mountainous regions with the unmodified Stokes’ kernel. Numéro de notice : A2015-391 Affiliation des auteurs : LASTIG LAREG (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2014-0026 En ligne : http://dx.oi.org/10.1515/jag-2014-0026 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76860 [article]

Application of archival aerial photogrammetry to quantify climate forcing of alpine landscapes / Natan Micheletti in Photogrammetric record, vol 30 n° 150 (June - August 2015)  

Public [article]  inPhotogrammetric record > vol 30 n° 150 (June - August 2015) . - pp 143 - 165 Titre : Application of archival aerial photogrammetry to quantify climate forcing of alpine landscapes Type de document : Article/Communication Auteurs : Natan Micheletti, Auteur ; Stuart Lane, Auteur ; Jim H. Chandler, Auteur Année de publication : 2015 Article en page(s) : pp 143 - 165 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] Alpes [Termes IGN] analyse diachronique [Termes IGN] changement climatique [Termes IGN] érosion [Termes IGN] image aérienne [Termes IGN] montagne [Termes IGN] Suisse [Termes IGN] traitement d'image Résumé : (auteur) Recent and future climate change may lead to landscape changes in geomorphic processes and process rates. Such modifications are likely to be widely distributed, making their direct measurement difficult and there are almost no such measurements at decadal intervals. Aerial imagery has been acquired by many national agencies since the 1950s and significant archives remain. Unlocking the information from these data sources is important because their timescale may inform significant unresolved hypotheses regarding the impact of rapid climate change on Alpine environments. However, such photogrammetric applications are challenging because of topographic complexity (including occlusions and large elevation ranges) and variations in image texture. A complete workflow is described from raw data to the treatment and interpretation of results. This is applied to imagery of Val d'Héréns, Switzerland, a landscape containing an assemblage of glacial, periglacial, hillslope and fluvial landforms across a height range of 1800 to 3600 m from the 1960s to the present. These changes reveal important characteristics of landscape scale erosion and deposition at the decadal scale. Numéro de notice : A2015-414 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12099 Date de publication en ligne : 14/05/2015 En ligne : https://doi.org/10.1111/phor.12099 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76911 [article]

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106-2015021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Effect of slope on treetop detection using a LiDAR Canopy Height Model / Anahita Khosravipour in ISPRS Journal of photogrammetry and remote sensing, vol 104 (June 2015)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 104 (June 2015) . - pp 44 - 52 Titre : Effect of slope on treetop detection using a LiDAR Canopy Height Model Type de document : Article/Communication Auteurs : Anahita Khosravipour, Auteur ; Tiejun Wang, Auteur ; Martin Isenburg, Auteur ; Kourosh Khoshelham, Auteur Année de publication : 2015 Article en page(s) : pp 44 - 52 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] houppier [Termes IGN] modèle numérique de surface de la canopée [Termes IGN] pente [Termes IGN] Pinus mugo subsp. uncinata [Termes IGN] Pinus sylvestris [Termes IGN] semis de points Résumé : (auteur) Canopy Height Models (CHMs) or normalized Digital Surface Models (nDSM) derived from LiDAR data have been applied to extract relevant forest inventory information. However, generating a CHM by height normalizing the raw LiDAR points is challenging if trees are located on complex terrain. On steep slopes, the raw elevation values located on either the downhill or the uphill part of a tree crown are height-normalized with parts of the digital terrain model that may be much lower or higher than the tree stem base, respectively. In treetop detection, a highest crown return located in the downhill part may prove to be a “false” local maximum that is distant from the true treetop. Based on this observation, we theoretically and experimentally quantify the effect of slope on the accuracy of treetop detection. The theoretical model presented a systematic horizontal displacement of treetops that causes tree height to be systematically displaced as a function of terrain slope and tree crown radius. Interestingly, our experimental results showed that the effect of CHM distortion on treetop displacement depends not only on the steepness of the slope but more importantly on the crown shape, which is species-dependent. The influence of the systematic error was significant for Scots pine, which has an irregular crown pattern and weak apical dominance, but not for mountain pine, which has a narrow conical crown with a distinct apex. Based on our findings, we suggest that in order to minimize the negative effect of steep slopes on the CHM, especially in heterogeneous forest with multiple species or species which change their morphological characteristics as they mature, it is best to use raw elevation values (i.e., use the un-normalized DSM) and compute the height after treetop detection. Numéro de notice : A2015-700 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2015.02.013 En ligne : https://doi.org/10.1016/j.isprsjprs.2015.02.013 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78336 [article]

UAV photogrammetry for topographic monitoring of coastal areas / J.A. Gonçalves in ISPRS Journal of photogrammetry and remote sensing, vol 104 (June 2015)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 104 (June 2015) . - pp 101 - 111 Titre : UAV photogrammetry for topographic monitoring of coastal areas Type de document : Article/Communication Auteurs : J.A. Gonçalves, Auteur ; R. Henriques, Auteur Année de publication : 2015 Article en page(s) : pp 101 - 111 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] Agisoft Photoscan [Termes IGN] chambre non métrique [Termes IGN] drone [Termes IGN] dune [Termes IGN] modèle numérique de surface [Termes IGN] photogrammétrie numérique [Termes IGN] plage [Termes IGN] point d'appui [Termes IGN] Portugal [Termes IGN] semis de points [Termes IGN] surveillance du littoral Résumé : (auteur) Coastal areas suffer degradation due to the action of the sea and other natural and human-induced causes. Topographical changes in beaches and sand dunes need to be assessed, both after severe events and on a regular basis, to build models that can predict the evolution of these natural environments. This is an important application for airborne LIDAR, and conventional photogrammetry is also being used for regular monitoring programs of sensitive coastal areas. This paper analyses the use of unmanned aerial vehicles (UAV) to map and monitor sand dunes and beaches. A very light plane (SwingletCam) equipped with a very cheap, non-metric camera was used to acquire images with ground resolutions better than 5 cm. The Agisoft Photoscan software was used to orientate the images, extract point clouds, build a digital surface model and produce orthoimage mosaics. The processing, which includes automatic aerial triangulation with camera calibration and subsequent model generation, was mostly automated. To achieve the best positional accuracy for the whole process, signalised ground control points were surveyed with a differential GPS receiver. Two very sensitive test areas on the Portuguese northwest coast were analysed. Detailed DSMs were obtained with 10 cm grid spacing and vertical accuracy (RMS) ranging from 3.5 to 5.0 cm, which is very similar to the image ground resolution (3.2–4.5 cm). Where possible to assess, the planimetric accuracy of the orthoimage mosaics was found to be subpixel. Within the regular coastal monitoring programme being carried out in the region, UAVs can replace many of the conventional flights, with considerable gains in the cost of the data acquisition and without any loss in the quality of topographic and aerial imagery data. Numéro de notice : A2015--002 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2015.02.009 En ligne : https://doi.org/10.1016/j.isprsjprs.2015.02.009 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78337 [article]

Using hachures to construct a 3D doline model automatically / Nai Yang in Cartographica, vol 50 n° 2 (Summer 2015)  

Public [article]  inCartographica > vol 50 n° 2 (Summer 2015) . - pp 86 - 93 Titre : Using hachures to construct a 3D doline model automatically Type de document : Article/Communication Auteurs : Nai Yang, Auteur ; Lin Wan, Auteur ; G. Zheng, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 86 - 93 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rédaction cartographique [Termes IGN] effondrement de terrain [Termes IGN] grotte [Termes IGN] hachure [Termes IGN] représentation cartographique 3D Résumé : (auteur) All types of relief features are usually represented by a unified digital terrain model on 3D topographic maps. Few studies have considered the differences in relief characteristics and terrain complexity. Hachures are often used to construct the relief symbols on 2D topographic maps, but they are less used on 3D topographic maps. This article uses hachures to construct a 3D doline model and divides them into three types: outlines, ridge lines, and break lines. We present the extraction method for doline outlines, consider the rules of visual perception under different illumination conditions, and study the mathematical models for representing the morphological characteristics of the doline with regard to the following aspects: width, arrangement density, and grey value of hachures. Finally, we introduce a process for 3D modelling of dolines on the basis of the above discussion. Experimental results indicate that the proposed model achieves a good 3D visual representation of dolines. Furthermore, the proposed model can also be used as a reference for the creation of 3D models of other negative relief features. Numéro de notice : A2015-273 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.3138/cart.50.2.2793 En ligne : http://www.utpjournals.press/doi/full/10.3138/cart.50.2.2793 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76386 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
031-2015021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Evaluation of Lidar-derived DEMs through terrain analysis and field / Cody P. Gillin in Photogrammetric Engineering & Remote Sensing, PERS, vol 81 n° 5 (May 2015)  

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Infrastructures de données géographiques : quelle contribution à la gestion intégrée des zones côtières françaises ? / Jade Georis-Creuseveau in VertigO, vol 15 n° 1 (mai 2015)  

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Apport du LiDAR dans le géoréférencement d'images hyperspectrales en vue d'un couplage LiDAR/hyperspectral / Antoine Ba in Revue Française de Photogrammétrie et de Télédétection, n° 210 (Avril 2015)  

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L'approche détection des changements pour estimer l'humidité du sol en milieu semi-aride à partir d'images ASAR, cas des hautes plaines de l'Est de l'Algérie / Mokhtar Guerfi in Revue Française de Photogrammétrie et de Télédétection, n° 210 (Avril 2015)  

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Les séries de végétation de la vallée d’Ascu (Corse) : typologie et cartographie au 1:25 000 / Pauline Delbosc in Ecologia mediterranea, vol 41 n° 1 (2015)    

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Geospatial analysis of land-use change processes in a densely populated coastal city: the case of Port Harcourt, south-east Nigeria / Glory O. Enaruvbe in Geocarto international, vol 30 n° 3 - 4 (March - April 2015)  

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Les Alpes d'Helbronner / Daniel Léon (2015)

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Analysis of spatial variability of near-surface soil moisture to increase rainfall-runoff modelling accuracy in SW Hungary / P. Hegedüs in Open geosciences, vol 7 n° 1 (January 2015)  

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Angry birds at altitude / Matthew Wade in GEO: Geoconnexion international, vol 14 n° 1 (January 2015)

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Coastal digital surface model on low contrast images / Ana-Maria Rosu (2015)  

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Geo-spatial modelling with unbalanced data: modelling the spatial pattern of human activity during the Stone Age / Jaroslav Jasiewicz in Open geosciences, vol 7 n° 1 (January 2015)  

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Gradiomètre planaire aéroporté pour l'étude de la gravité en zones littorales / Karim Douch (2015)  

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Homogeneous geovisualization of coastal areas from heterogeneous spatio-temporal data / Antoine Masse (2015)  

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Intempéries : crises et postcrises. Quels retours d'expérience ? / Jean-François Gaudet (2015)

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Morphotectonic and morphodynamic investigations revealed by isobase surfaces analysis and derived differential mapping using GIS, Teboursouk area, northern Tunisia / Tarek Slama in Earth Science Informatics, vol 8 n° 4 (2015)  

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Seeing through shadow: Modelling surface irradiance for topographic correction of Landsat ETM+ data / Tobias Schulmann in ISPRS Journal of photogrammetry and remote sensing, vol 99 (January 2015)  

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Suivi de l’enneigement saisonnier sur un site de haute altitude par balayage laser terrestre / Aymeric Richard (2015) 

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Étude de l’évolution morphosédimentaire à court et moyen terme du système dune/plage de Korba (façade orientale du Cap Bon, Tunisie) / Zouhour Yahyaoui in Revue internationale de géomatique, vol 24 n° 4 (décembre 2014 - février 2015)  

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Multi-UAV surveillance over forested regions / Vengatesan Govindaraju in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 12 (December 2014)  

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Perceptually shaded slope maps for the visualization of digital surface models / Thomas J. Pingel in Cartographica, vol 49 n° 4 (Winter 2014)  

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