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Influence of sample size on automatic positional accuracy assessment methods for urban areas / Francisco Javier Ariza-López in ISPRS International journal of geo-information, vol 7 n° 6 (June 2018)  

Public [article]  inISPRS International journal of geo-information > vol 7 n° 6 (June 2018) Titre : Influence of sample size on automatic positional accuracy assessment methods for urban areas Type de document : Article/Communication Auteurs : Francisco Javier Ariza-López, Auteur ; Juan J. Ruiz-Lendínez, Auteur ; Manuel A. Ureña-Cámara, Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes descripteurs IGN] base de données urbaines [Termes descripteurs IGN] distance de Kolmogorov-Smirnov [Termes descripteurs IGN] échantillon [Termes descripteurs IGN] polygone [Termes descripteurs IGN] précision de localisation [Termes descripteurs IGN] précision planimétrique [Termes descripteurs IGN] qualité des données [Termes descripteurs IGN] zone urbaine Résumé : (Auteur) In recent years, new approaches aimed to increase the automation level of positional accuracy assessment processes for spatial data have been developed. However, in such cases, an aspect as significant as sample size has not yet been addressed. In this paper, we study the influence of sample size when estimating the planimetric positional accuracy of urban databases by means of an automatic assessment using polygon-based methodology. Our study is based on a simulation process, which extracts pairs of homologous polygons from the assessed and reference data sources and applies two buffer-based methods. The parameter used for determining the different sizes (which range from 5 km up to 100 km) has been the length of the polygons’ perimeter, and for each sample size 1000 simulations were run. After completing the simulation process, the comparisons between the estimated distribution functions for each sample and population distribution function were carried out by means of the Kolmogorov–Smirnov test. Results show a significant reduction in the variability of estimations when sample size increased from 5 km to 100 km. Numéro de notice : A2018-346 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/ijgi7060200 date de publication en ligne : 28/05/2018 En ligne : https://doi.org/10.3390/ijgi7060200 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90570 [article]

Modeling diameter distributions in radiata pine plantations in Spain with existing countrywide LiDAR data / Manuel Arias-Rodil in Annals of Forest Science [en ligne], vol 75 n° 2 (June 2018)  

Public [article]  inAnnals of Forest Science [en ligne] > vol 75 n° 2 (June 2018) Titre : Modeling diameter distributions in radiata pine plantations in Spain with existing countrywide LiDAR data Type de document : Article/Communication Auteurs : Manuel Arias-Rodil, Auteur ; Ulises Diéguez-Aranda, Auteur ; Juan Gabriel Álvarez-González, Auteur ; César Pérez-Cruzado, Auteur ; et al., Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] classification par forêts aléatoires [Termes descripteurs IGN] diamètre des arbres [Termes descripteurs IGN] distance de Kolmogorov-Smirnov [Termes descripteurs IGN] données altimétriques [Termes descripteurs IGN] données lidar [Termes descripteurs IGN] données localisées 3D [Termes descripteurs IGN] Espagne [Termes descripteurs IGN] inventaire forestier (techniques et méthodes) [Termes descripteurs IGN] Pinus radiata [Vedettes matières IGN] Inventaire forestier Résumé : (Auteur) Key message: We evaluated the use of low-density airborne laser scanning data to estimate diameter distributions in radiata pine plantations. The moment-based parameter recovery method was used to estimate the diameter distributions, considering LiDAR metrics as explanatory variables. The fitted models explained more than 77% of the observed variability. This approach can be replicated every 6 years (temporal cover planned for countrywide LiDAR flights in Spain). Context:The estimation of stand diameter distribution is informative for forest managers in terms of stand structure, forest growth model inputs, and economic timber value. In this sense, airborne LiDAR may represent an adequate source of information. Aims: The objective was to evaluate the use of low-density Spanish countrywide LiDAR data for estimating diameter distributions in Pinus radiata D. Don stands in NW Spain. Methods: The empirical distributions were obtained from 25 sample plots. We applied the moment-based parameter recovery method in combination with the Weibull function to estimate the diameter distributions, considering LiDAR metrics as explanatory variables. We evaluated the results by using the Kolmogorov–Smirnov (KS) test and a classification tree and random forest (RF) to relate the KS test result for each plot to stand-level variables. Results: The models used to estimate average (dm) and quadratic (dg) mean diameters from LiDAR metrics, required for recovery of the Weibull parameters, explained a high percentage of the observed variance (77 and 80%, respectively), with RMSE values of 3.626 and 3.422 cm for the same variables. However, the proportion of plots accepted by the KS was low. This poor performance may be due to the strictness of the KS test and/or by the characteristics of the LiDAR flight. Conclusion: The results justify the assessment of this approach over different species and forest types in regional or countrywide surveys. Numéro de notice : A2018-327 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-018-0712-z date de publication en ligne : 16/03/2018 En ligne : https://doi.org/10.1007/s13595-018-0712-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90470 [article]