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Automated conflation of digital elevation model with reference hydrographic lines / Timofey Samsonov in ISPRS International journal of geo-information, vol 9 n° 5 (May 2020)  

Public [article]  inISPRS International journal of geo-information > vol 9 n° 5 (May 2020) . - 40 p. Titre : Automated conflation of digital elevation model with reference hydrographic lines Type de document : Article/Communication Auteurs : Timofey Samsonov, Auteur Année de publication : 2020 Article en page(s) : 40 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] alignement [Termes descripteurs IGN] cartographie hydrographique [Termes descripteurs IGN] conflation [Termes descripteurs IGN] données localisées [Termes descripteurs IGN] données vectorielles [Termes descripteurs IGN] modèle numérique de surface [Termes descripteurs IGN] réseau de drainage [Termes descripteurs IGN] Triangulated Irregular Network [Vedettes matières IGN] Généralisation Résumé : (auteur) Combining misaligned spatial data from different sources complicates spatial analysis and creation of maps. Conflation is a process that solves the misalignment problem through spatial adjustment or attribute transfer between similar features in two datasets. Even though a combination of digital elevation model (DEM) and vector hydrographic lines is a common practice in spatial analysis and mapping, no method for automated conflation between these spatial data types has been developed so far. The problem of DEM and hydrography misalignment arises not only in map compilation, but also during the production of generalized datasets. There is a lack of automated solutions which can ensure that the drainage network represented in the surface of generalized DEM is spatially adjusted with independently generalized vector hydrography. We propose a new method that performs the conflation of DEM with linear hydrographic data and is embeddable into DEM generalization process. Given a set of reference hydrographic lines, our method automatically recognizes the most similar paths on DEM surface called counterpart streams. The elevation data extracted from DEM is then rubbersheeted locally using the links between counterpart streams and reference lines, and the conflated DEM is reconstructed from the rubbersheeted elevation data. The algorithm developed for extraction of counterpart streams ensures that the resulting set of lines comprises the network similar to the network of ordered reference lines. We also show how our approach can be seamlessly integrated into a TIN-based structural DEM generalization process with spatial adjustment to pre-generalized hydrographic lines as additional requirement. The combination of the GEBCO_2019 DEM and the Natural Earth 10M vector dataset is used to illustrate the effectiveness of DEM conflation both in map compilation and map generalization workflows. Resulting maps are geographically correct and are aesthetically more pleasing in comparison to a straightforward combination of misaligned DEM and hydrographic lines without conflation. Numéro de notice : A2020-297 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/ijgi9050334 date de publication en ligne : 20/05/2020 En ligne : https://doi.org/10.3390/ijgi9050334 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95135 [article]

Regression modeling of reduction in spatial accuracy and detail for multiple geometric line simplification procedures / Timofey Samsonov in International journal of cartography, Vol 6 n° 1 (March 2020)  

Public [article]  inInternational journal of cartography > Vol 6 n° 1 (March 2020) . - pp 47 - 70 Titre : Regression modeling of reduction in spatial accuracy and detail for multiple geometric line simplification procedures Type de document : Article/Communication Auteurs : Timofey Samsonov, Auteur ; Olga P. Yakimova, Auteur Année de publication : 2020 Article en page(s) : pp 47 - 70 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] algorithme de Douglas-Peucker [Termes descripteurs IGN] algorithme de Visvalingam [Termes descripteurs IGN] modèle de régression [Termes descripteurs IGN] niveau de détail [Termes descripteurs IGN] précision cartographique [Termes descripteurs IGN] représentation des détails topographiques [Termes descripteurs IGN] simplification de contour [Vedettes matières IGN] Généralisation Résumé : (auteur) One of the important stages of map generalization is the selection of optimal simplification procedure for each spatial feature or feature type. Selected algorithms are then applied collaboratively to simplify the whole set of features. However, there is a lack of investigations that report a systematic approach of deriving a similar reduction in accuracy and detail by using different algorithms. In current paper we propose the solution to this problem on the basis of regression modeling between tolerance value of each algorithm and the value of some geometric measure which describes changes in accuracy and detail of the line. This allows fitting the regression model between tolerance values of the two selected algorithms which can be used to obtain similar simplification results. Regressions between Douglas-Peucker, Li-Openshaw and Visvalingam-Whyatt algorithm tolerance values are investigated. Application of methodology is illustrated on the example of three coastlines with significantly different spatial character. Results of the study show that regression coefficients depend highly both on the combination of the two algorithms, and on the character of the line. Finally, it is shown that a weighted combination of accuracy and detail regression models can be used to model the changes in level of detail of the line. Numéro de notice : A2020-071 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/23729333.2019.1615745 date de publication en ligne : 29/07/2019 En ligne : https://doi.org/10.1080/23729333.2019.1615745 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94634 [article]

Shape-adaptive geometric simplification of heterogeneous line datasets / Timofey Samsonov in International journal of geographical information science IJGIS, vol 31 n° 7-8 (July - August 2017)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 31 n° 7-8 (July - August 2017) . - pp 1485 - 1520 Titre : Shape-adaptive geometric simplification of heterogeneous line datasets Type de document : Article/Communication Auteurs : Timofey Samsonov, Auteur ; Olga P. Yakimova, Auteur Année de publication : 2017 Article en page(s) : pp 1485 - 1520 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] algorithme de Douglas-Peucker [Termes descripteurs IGN] données hétérogènes [Termes descripteurs IGN] généralisation automatique de données [Termes descripteurs IGN] généralisation cartographique [Termes descripteurs IGN] limite administrative [Termes descripteurs IGN] objet géographique linéaire [Termes descripteurs IGN] simplification de contour [Termes descripteurs IGN] traitement de données [Vedettes matières IGN] Généralisation Résumé : (Auteur) Line generalization is an essential data processing operation in geographic information systems and cartography. Many point reduction and simplification algorithms have been developed for this purpose. During the last three decades, several attempts have been made to develop approaches of generalization that adapt to the geometric properties of the processed lines. They typically incorporate line segmentation based on quantitative descriptions of the line shape. Little attention has been paid to the cases in which heterogeneous lines of different geometric character are mixed in one dataset. One common example is administrative borders, which often contain natural and artificial, smooth and sharp, schematic and non-schematic, and regular and irregular shapes. The tuning of the simplification algorithm based on a quantitative description of the shape would be ineffective here, since different algorithms must be applied to lines of different characters. In this article, we present a general method and generalization model for the simplification of such datasets. The properties of schematism, smoothness and regularity are used to differentiate various line characters. Three line characters, including irregular non-schematic, irregular schematic and regular orthogonal schematic, were selected for the current study. The developed generalization model consists of preprocessing, processing and postprocessing stages. Line segmentation based on the detection of different characters is performed during the preprocessing stage. Then, Li–Openshaw, Douglas–Peucker and orthogonal simplification are applied to the appropriate segments in the processing stage. Postprocessing enables the addition of extra regularity to the simplified shape. A visual and quantitative assessment of the results is provided and demonstrates the effectiveness of the developed approach in comparison with the global application of a single simplification algorithm. Numéro de notice : A2017-309 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2017.1306864 En ligne : http://dx.doi.org/10.1080/13658816.2017.1306864 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85356 [article]

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Morphometric mapping of topography by flowline hachures / Timofey Samsonov in Cartographic journal (the), vol 51 n° 1 (February 2014)

Public [article]  inCartographic journal (the) > vol 51 n° 1 (February 2014) . - pp 63 - 74 Titre : Morphometric mapping of topography by flowline hachures Type de document : Article/Communication Auteurs : Timofey Samsonov, Auteur Année de publication : 2014 Article en page(s) : pp 63 - 74 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rédaction cartographique [Termes descripteurs IGN] automatisation [Termes descripteurs IGN] géomorphométrie [Termes descripteurs IGN] hachure [Termes descripteurs IGN] rédaction cartographique [Termes descripteurs IGN] représentation du relief Résumé : (Auteur) Hachuring is a classic method of cartographic relief presentation that origins from perspective sketching of the surface. Hachuring was developed into strict and mathematically grounded planimetric method during the eighteenth century. Established by Lehmann in 1799, topographic hachures flourished during the first half of the nineteenth century and then were gradually replaced by contours. Today, hachures are still popular in presentation of anthropogenic relief on archaeological and topographic maps. Some elements of hachuring can be found in geomorphometric and hydrometeorological mapping, where flowlines and arrows are used to show the intensity and direction of the flow on the surface, or its aspect and slope. The study aims to reveal the potential of hachuring in further development as surface presentation method. Automated implementation of all original requirements for hachure construction is provided for the first time by new algorithm using vector flowlines. Then an advanced hachuring technique called ‘slope and aspect hachuring’ is presented which depicts slope, aspect and flow direction of the surface simultaneously. Slope and aspect hachuring is compared to traditional area colours to reveal its advantages and shortcomings in sight of morphometric mapping. Some applications of the method and directions of future research are suggested in concluding part. Numéro de notice : A2014-129 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33034 [article]

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