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Consistency of accuracy assessment indices for soft classification: simulation analysis / J. Chen in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 2 (March - April 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 2 (March - April 2010) . - pp 156 - 164 Titre : Consistency of accuracy assessment indices for soft classification: simulation analysis Type de document : Article/Communication Auteurs : J. Chen, Auteur ; X. Zhu, Auteur ; H. Imura, Auteur ; X. Chen, Auteur Année de publication : 2010 Article en page(s) : pp 156 - 164 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse comparative [Termes IGN] classification [Termes IGN] erreur moyenne quadratique [Termes IGN] estimation de précision [Termes IGN] Kappa de Cohen [Termes IGN] matrice de confusion [Termes IGN] niveau d'analyse [Termes IGN] précision cartographique [Termes IGN] précision décimétrique [Termes IGN] simulation Résumé : (Auteur) Accuracy assessment plays a crucial role in the implementation of soft classification. Even though many indices of accuracy assessment for soft classification have been proposed, the consistencies among these indices are not clear, and the impact of sample size on these consistencies has not been investigated. This paper examines two kinds of indices: map-level indices, including root mean square error (rmse), kappa, and overall accuracy (oa) from the sub-pixel confusion matrix (SCM); and category-level indices, including crmse, user accuracy (ua) and producer accuracy (pa). A careful simulation was conducted to investigate the consistency of these indices and the effect of sample size. The major findings were as follows: (1) The map-level indices are highly consistent with each other, whereas the category-level indices are not. (2) The consistency among map-level and category-level indices becomes weaker when the sample size decreases. (3) The rmse is more affected by error distribution among classes than are kappa and oa. Based on these results, we recommend that rmse can be used for map-level accuracy due to its simplicity, although kappa and oa may be better alternatives when the sample size is limited because the two indices are affected less by the error distribution among classes. We also suggest that crmse should be provided when map users are not concerned about the error source, whereas ua and pa are more useful when the complete information about different errors is required. The results of this study will be of benefit to the development and application of soft classifiers. Copyright ISPRS Numéro de notice : A2010-090 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2009.10.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2009.10.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30286 [article]

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Delineation and geometric modeling of road networks / C. Poullis in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 2 (March - April 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 2 (March - April 2010) . - pp 165 - 181 Titre : Delineation and geometric modeling of road networks Type de document : Article/Communication Auteurs : C. Poullis, Auteur ; S. You, Auteur Année de publication : 2010 Article en page(s) : pp 165 - 181 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] arc [Termes IGN] axe médian [Termes IGN] données lidar [Termes IGN] extraction automatique [Termes IGN] filtre de Gabor [Termes IGN] image satellite [Termes IGN] photographie aérienne [Termes IGN] regroupement de données [Termes IGN] réseau routier Résumé : (Auteur) In this work we present a novel vision-based system for automatic detection and extraction of complex road networks from various sensor resources such as aerial photographs, satellite images, and LiDAR. Uniquely, the proposed system is an integrated solution that merges the power of perceptual grouping theory (Gabor filtering, tensor voting) and optimized segmentation techniques (global optimization using graph-cuts) into a unified framework to address the challenging problems of geospatial feature detection and classification. Firstly, the local precision of the Gabor filters is combined with the global context of the tensor voting to produce accurate classification of the geospatial features. In addition, the tensorial representation used for the encoding of the data eliminates the need for any thresholds, therefore removing any data dependencies. Secondly, a novel orientation-based segmentation is presented which incorporates the classification of the perceptual grouping, and results in segmentations with better defined boundaries and continuous linear segments. Finally, a set of gaussian-based filters are applied to automatically extract centerline information (magnitude, width and orientation). This information is then used for creating road segments and transforming them to their polygonal representations. Numéro de notice : A2010-091 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2009.10.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2009.10.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30287 [article]

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A DEM generalization by minor valley branch detection and grid filling / Tinghua Ai in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 2 (March - April 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 2 (March - April 2010) . - pp 198 - 207 Titre : A DEM generalization by minor valley branch detection and grid filling Type de document : Article/Communication Auteurs : Tinghua Ai, Auteur ; J. Li, Auteur Année de publication : 2010 Article en page(s) : pp 198 - 207 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] détection automatique [Termes IGN] données multiéchelles [Termes IGN] généralisation automatique de données [Termes IGN] généralisation de MNT [Termes IGN] lissage de données [Termes IGN] modèle numérique de surface [Termes IGN] représentation du relief [Termes IGN] réseau hydrographique [Termes IGN] vallée Résumé : (Auteur) As an important method of terrain representation, a DEM usually needs to be generalized at multiple resolutions in order to adapt to different applications. The preservation of main landscape features is an important constraint in DEM generalization. The traditional generalization method based on signal processing by resampling or low-pass filtering is just a data compression operation rather than the abstraction of real information. This study develops a structured analysis method to generalize DEM data through the identification of minor valleys and filling the corresponding depression positions. The generalization process has two steps: geographic decision and geometric operation. According to their hydrological significance, the unimportant valley branches are detected and their corresponding coverage is filled by raising the terrain to make the terrain surface smoother. In contrast to the conventional algorithms based on image processing, this method is able to retain the main geographical characteristics more effectively in terrain representation. Copyright ISPRS Numéro de notice : A2010-092 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2009.11.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2009.11.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30288 [article]

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Real-time registration of airborne laser with sub-decimeter accuracy / Jan Skaloud in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 2 (March - April 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 2 (March - April 2010) . - pp 208 - 217 Titre : Real-time registration of airborne laser with sub-decimeter accuracy Type de document : Article/Communication Auteurs : Jan Skaloud, Auteur ; Philipp Schaer, Auteur ; P. Tome, Auteur ; Yannick Stebler, Auteur Année de publication : 2010 Article en page(s) : pp 208 - 217 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] covariance [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] GPS en mode différentiel [Termes IGN] GPS-INS [Termes IGN] lasergrammétrie [Termes IGN] mesurage de phase [Termes IGN] positionnement cinématique en temps réel [Termes IGN] précision absolue [Termes IGN] précision décimétrique [Termes IGN] précision du positionnement [Termes IGN] semis de points [Termes IGN] télémétrie laser aéroporté [Termes IGN] temps réel Résumé : (Auteur) This paper presents a methodology for the precise registering of airborne laser data directly in flight with an accuracy that is sufficient for the majority of derived products, such as digital terrain models. We first present the strategy that integrates GPS/INS/LiDAR data for generating laser point clouds directly in flight and analyzes their accuracy. The latter requires the implementation of a functional covariance propagation on-line for all the system components (i.e. trajectory, laser, system calibration) to which influences of scanning geometry are added at the end of a flight line. The study of scanning geometry necessitates the classification of vegetation and coarse estimation of the terrain normal. This is achieved by a method that we formerly proposed for off-line quality analysis. The second part of the paper focuses on the positioning component. In high resolution scanning performed close to the terrain, the absolute accuracy of the resulting point cloud depends mainly on the quality of the trajectory which is related to the type of GPS solution (e.g. absolute positioning, DGPS, RTK). To reach sub-decimeter accuracy for the point cloud in the real-time, an RTK-GPS solution is needed. This requires the establishment of a communication link for the transmission of GPS corrections (or measurements). We analyze the usability of RTK-GPS/ALS acquired during several flights using different communication methods in the particular context of helicopter based missions. We focus mainly on the exploitation of nation-wide reference GNSS networks and confirm experimentally that the real-time registration of airborne laser data is feasible with sub-decimeter accuracy. Such quality is sufficient not only for a wide range of applications, but it also opens new opportunities for monitoring missions that require a short reaction time. Finally, we concentrate on situations when the phase and code corrections cannot be transmitted, and the quality of the differential carrier-phase positioning needs to be predicted. We validate the previously introduced indicators of positioning quality by simulated degradation of the input data. Copyright ISPRS Numéro de notice : A2010-093 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2009.12.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2009.12.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30289 [article]

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Using simulated Terrestrial Laser Scanning to analyse errors in high-resolution scan data of irregular surfaces / R. Hodge in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 2 (March - April 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 2 (March - April 2010) . - pp 227 - 240 Titre : Using simulated Terrestrial Laser Scanning to analyse errors in high-resolution scan data of irregular surfaces Type de document : Article/Communication Auteurs : R. Hodge, Auteur Année de publication : 2010 Article en page(s) : pp 227 - 240 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] erreur en position [Termes IGN] lasergrammétrie [Termes IGN] modèle numérique de surface [Termes IGN] semis de points [Termes IGN] simulation [Termes IGN] surface hétérogène [Termes IGN] télémétrie laser terrestre Résumé : (Auteur) Terrestrial Laser Scanning (TLS) is increasingly being used to collect mm-resolution surface data from a broad range of environments. When scanning complex surfaces, interactions between the surface topography, laser footprint and scanner precision can introduce errors into the point cloud. Quantification of these errors is, however, limited by the availability of independent measurement techniques. This research presents simulated TLS as a new approach to error quantification. Two sets of experiments are presented. The first set demonstrates that simulated TLS is able to reproduce real TLS data from a plane and a pebble. The second set uses simulated TLS to assess a methodology developed for the collection and processing of field TLS data. Simulated TLS data is collected from surfaces up to not, vert, similar1 m2 created from regular arrays of uniform spheres (sphere diameters of 10 to 100 mm) and irregular arrays of mixed spheres (median sphere diameters of 16 to 94 mm). These data were analysed to (i) assess the effectiveness of the processing methodology at removing erroneous points; (ii) quantify the magnitude of errors in a digital surface model (DSM) interpolated from the processed point cloud; and (iii) investigate the extent to which the interpolated DSMs retained the geometric properties of the original surfaces. The processing methodology was found to be effective, especially on data from coarser surfaces, with the retained points typically having an inter-quartile range (IQR) of point errors of not, vert, similar2 mm. DSM errors varied as a function of sphere size and packing, with DSM errors having an IQR of not, vert, similar2 mm for the regular surfaces and not, vert, similar4 mm for the irregular surfaces. Finally, whilst in the finer surfaces point and DSM errors were a substantial proportion of the sphere diameters, geometrical analysis indicated that the DSMs still reproduced properties of the original surface such as semivariance and some percentiles of the surface elevation distribution. Copyright ISPRS Numéro de notice : A2010-094 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2010.01.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2010.01.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30290 [article]

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Monitoring forest areas from continental to territorial levels using a sample of medium spatial resolution satellite imagery / Hugh Eva in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 2 (March - April 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 2 (March - April 2010) . - pp 191 - 197 Titre : Monitoring forest areas from continental to territorial levels using a sample of medium spatial resolution satellite imagery Type de document : Article/Communication Auteurs : Hugh Eva, Auteur ; Silvia Carboni, Auteur ; Frédéric Achard, Auteur ; Nicolas Stach , Auteur ; Laurent Durieux, Auteur ; Jean-François Faure, Auteur ; Danilo Mollicone, Auteur Année de publication : 2010 Article en page(s) : pp 191 - 197 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] Amazonie [Termes IGN] déboisement [Termes IGN] forêt tropicale [Termes IGN] Guyane (département français) [Termes IGN] image à moyenne résolution [Termes IGN] image Landsat-TM [Termes IGN] image SPOT-HRV [Termes IGN] inventaire forestier national (données France) Résumé : (auteur) A global systematic sampling scheme has been developed by the UN FAO and the EC TREES project to estimate rates of deforestation at global or continental levels at intervals of 5 to 10 years. This global scheme can be intensified to produce results at the national level. In this paper, using surrogate observations, we compare the deforestation estimates derived from these two levels of sampling intensities (one, the global, for the Brazilian Amazon and the other, national, for French Guiana) to estimates derived from the official inventories. We also report the precisions that are achieved due to sampling errors and, in the case of French Guiana, compare such precision with the official inventory precision. We extract nine sample data sets from the official wall-to-wall deforestation map derived from satellite interpretations produced for the Brazilian Amazon for the year 2002 to 2003. This global sampling scheme estimate gives 2.81 million ha of deforestation (mean from nine simulated replicates) with a standard error of 0.10 million ha. This compares with the full population estimate from the wall-to-wall interpretations of 2.73 million ha deforested, which is within one standard error of our sampling test estimate. The relative difference between the mean estimate from sampling approach and the full population estimate is 3.1%, and the standard error represents 4.0% of the full population estimate. This global sampling is then intensified to a territorial level with a case study over French Guiana to estimate deforestation between the years 1990 and 2006. For the historical reference period, 1990, Landsat-5 Thematic Mapper data were used. A coverage of SPOT-HRV imagery at 20 m × 20 m resolution acquired at the Cayenne receiving station in French Guiana was used for year 2006. Our estimates from the intensified global sampling scheme over French Guiana are compared with those produced by the national authority to report on deforestation rates under the Kyoto protocol rules for its overseas department. The latter estimates come from a sample of nearly 17,000 plots analyzed from same spatial imagery acquired between year 1990 and year 2006. This sampling scheme is derived from the traditional forest inventory methods carried out by IFN (Inventaire Forestier National). Our intensified global sampling scheme leads to an estimate of 96,650 ha deforested between 1990 and 2006, which is within the 95% confidence interval of the IFN sampling scheme, which gives an estimate of 91,722 ha, representing a relative difference from the IFN of 5.4%. These results demonstrate that the intensification of the global sampling scheme can provide forest area change estimates close to those achieved by official forest inventories ( Numéro de notice : A2010-695 Affiliation des auteurs : IFN+Ext (1958-2011) Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1016/j.isprsjprs.2009.10.008 Date de publication en ligne : 24/11/2009 En ligne : https://doi.org/10.1016/j.isprsjprs.2009.10.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100145 [article]

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