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Forest canopy height estimation using ICESat/GLAS data and error factor analysis in Hokkaido, Japan / Masato Hayashi in ISPRS Journal of photogrammetry and remote sensing, vol 81 (July 2013)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 81 (July 2013) . - pp 12 - 18 Titre : Forest canopy height estimation using ICESat/GLAS data and error factor analysis in Hokkaido, Japan Type de document : Article/Communication Auteurs : Masato Hayashi, Auteur ; Nobuko Saigusa, Auteur ; Hiroyuki Oguma, Auteur ; Yoshiki Ymagata, Auteur Année de publication : 2013 Article en page(s) : pp 12 - 18 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] canopée [Termes IGN] données ICEsat [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] forêt [Termes IGN] hauteur de la végétation [Termes IGN] Hokkaido (Japon) [Termes IGN] modèle numérique de surface [Termes IGN] pente Résumé : (Auteur) Spaceborne light detection and ranging (LiDAR) enables us to obtain information about vertical forest structure directly, and it has often been used to measure forest canopy height or above-ground biomass. However, little attention has been given to comparisons of the accuracy of the different estimation methods of canopy height or to the evaluation of the error factors in canopy height estimation. In this study, we tested three methods of estimating canopy height using the Geoscience Laser Altimeter System (GLAS) onboard NASA’s Ice, Cloud, and land Elevation Satellite (ICESat), and evaluated several factors that affected accuracy. Our study areas were Tomakomai and Kushiro, two forested areas on Hokkaido in Japan. The accuracy of the canopy height estimates was verified by ground-based measurements. We also conducted a multivariate analysis using quantification theory type I (multiple-regression analysis of qualitative data) and identified the observation conditions that had a large influence on estimation accuracy. The method using the digital elevation model was the most accurate, with a root-mean-square error (RMSE) of 3.2 m. However, GLAS data with a low signal-to-noise ratio (?10.0) and that taken from September to October 2009 had to be excluded from the analysis because the estimation accuracy of canopy height was remarkably low. After these data were excluded, the multivariate analysis showed that surface slope had the greatest effect on estimation accuracy, and the accuracy dropped the most in steeply sloped areas. We developed a second model with two equations to estimate canopy height depending on the surface slope, which improved estimation accuracy (RMSE = 2.8 m). These results should prove useful and provide practical suggestions for estimating forest canopy height using spaceborne LiDAR. Numéro de notice : A2013-385 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.04.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.04.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32523 [article]

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A shape-based segmentation method for mobile laser scanning point clouds / Yang Bisheng in ISPRS Journal of photogrammetry and remote sensing, vol 81 (July 2013)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 81 (July 2013) . - pp 19 - 30 Titre : A shape-based segmentation method for mobile laser scanning point clouds Type de document : Article/Communication Auteurs : Yang Bisheng, Auteur ; Zhen Dong, Auteur Année de publication : 2013 Article en page(s) : pp 19 - 30 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] classification par séparateurs à vaste marge [Termes IGN] connexité (topologie) [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] segmentation [Termes IGN] semis de points [Termes IGN] traitement automatique de données Résumé : (Auteur) Segmentation of mobile laser point clouds of urban scenes into objects is an important step for post-processing (e.g., interpretation) of point clouds. Point clouds of urban scenes contain numerous objects with significant size variability, complex and incomplete structures, and holes or variable point densities, raising great challenges for the segmentation of mobile laser point clouds. This paper addresses these challenges by proposing a shape-based segmentation method. The proposed method first calculates the optimal neighborhood size of each point to derive the geometric features associated with it, and then classifies the point clouds according to geometric features using support vector machines (SVMs). Second, a set of rules are defined to segment the classified point clouds, and a similarity criterion for segments is proposed to overcome over-segmentation. Finally, the segmentation output is merged based on topological connectivity into a meaningful geometrical abstraction. The proposed method has been tested on point clouds of two urban scenes obtained by different mobile laser scanners. The results show that the proposed method segments large-scale mobile laser point clouds with good accuracy and computationally effective time cost, and that it segments pole-like objects particularly well. Numéro de notice : A2013-386 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.04.002 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.04.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32524 [article]

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Independent two-step thresholding of binary images in inter-annual land cover change/no-change identification / Priyakant Sinha in ISPRS Journal of photogrammetry and remote sensing, vol 81 (July 2013)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 81 (July 2013) . - pp 31 - 43 Titre : Independent two-step thresholding of binary images in inter-annual land cover change/no-change identification Type de document : Article/Communication Auteurs : Priyakant Sinha, Auteur ; Lalit Kumar, Auteur Année de publication : 2013 Article en page(s) : pp 31 - 43 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] analyse comparative [Termes IGN] analyse diachronique [Termes IGN] détection de changement [Termes IGN] écart type [Termes IGN] image binaire [Termes IGN] Normalized Difference Vegetation Index [Termes IGN] occupation du sol [Termes IGN] segmentation binaire [Termes IGN] seuillage d'image Résumé : (Auteur) Binary images from one or more spectral bands have been used in many studies for land-cover change/no-change identification in diverse climatic conditions. Determination of appropriate threshold levels for change/no-change identification is a critical factor that influences change detection result accuracy. The most used method to determine the threshold values is based on the standard deviation (SD) from the mean, assuming the amount of change (due to increase or decrease in brightness values) to be symmetrically distributed on a standard normal curve, which is not always true. Considering the asymmetrical nature of distribution histogram for the two sides, this study proposes a relatively simple and easy ‘Independent Two-Step’ thresholding approach for optimal threshold value determination for spectrally increased and decreased part using Normalized Difference Vegetation Index (NDVI) difference image. Six NDVI differencing images from 2007 to 2009 of different seasons were tested for inter-annual or seasonal land cover change/no-change identification. The relative performances of the proposed and two other methods towards the sensitivity of distributions were tested and an improvement of ~3% in overall accuracy and of ~0.04 in Kappa was attained with the Proposed Method. This study demonstrated the importance of consideration of normality of data distributions in land-cover change/no-change analysis. Numéro de notice : A2013-387 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.03.010 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.03.010 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32525 [article]

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Filtering airborne LiDAR data by embedding smoothness-constrained segmentation in progressive TIN densification / Jixian Zhang in ISPRS Journal of photogrammetry and remote sensing, vol 81 (July 2013)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 81 (July 2013) . - pp 44 - 59 Titre : Filtering airborne LiDAR data by embedding smoothness-constrained segmentation in progressive TIN densification Type de document : Article/Communication Auteurs : Jixian Zhang, Auteur ; Xiangguo Lin, Auteur Année de publication : 2013 Article en page(s) : pp 44 - 59 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] densification [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] filtrage du signal [Termes IGN] segmentation [Termes IGN] semis de points [Termes IGN] traitement automatique de données [Termes IGN] Triangulated Irregular Network Résumé : (Auteur) Progressive TIN densification (PTD) is one of the classic methods for filtering airborne LiDAR point clouds. However, it may fail to preserve ground measurements in areas with steep terrain. A method is proposed to improve the PTD using a point cloud segmentation method, namely segmentation using smoothness constraint (SUSC). The classic PTD has two core steps. The first is selecting seed points and constructing the initial TIN. The second is an iterative densification of the TIN. Our main improvement is embedding the SUSC between these two steps. Specifically, after selecting the lowest points in each grid cell as initial ground seed points, SUSC is employed to expand the set of ground seed points as many as possible, as this can identify more ground seed points for the subsequent densification of the TIN-based terrain model. Seven datasets of ISPRS Working Group III/3 are utilized to test our proposed algorithm and the classic PTD. Experimental results suggest that, compared with the PTD, the proposed method is capable of preserving discontinuities of landscapes and reducing the omission errors and total errors by approximately 10% and 6% respectively, which would significantly decrease the cost of the manual operation required for correcting the result in post-processing. Numéro de notice : A2013-388 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.04.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.04.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32526 [article]

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Semi-automated analysis of high-resolution aerial images to quantify docks in glacial lakes / Marcus W. Beck in ISPRS Journal of photogrammetry and remote sensing, vol 81 (July 2013)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 81 (July 2013) . - pp 60 - 69 Titre : Semi-automated analysis of high-resolution aerial images to quantify docks in glacial lakes Type de document : Article/Communication Auteurs : Marcus W. Beck, Auteur ; Bruce Vondracek, Auteur ; Lorin Hatch, Auteur ; Jason Vinje, Auteur Année de publication : 2013 Article en page(s) : pp 60 - 69 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] détection d'objet [Termes IGN] image aérienne [Termes IGN] lac [Termes IGN] Minnesota (Etats-Unis) [Termes IGN] pêche [Termes IGN] ressources aquatiques [Termes IGN] surveillance écologique Résumé : (Auteur) Lake resources can be negatively affected by environmental stressors originating from multiple sources and different spatial scales. Shoreline development, in particular, can negatively affect lake resources through decline in habitat quality, physical disturbance, and impacts on fisheries. The development of remote sensing techniques that efficiently characterize shoreline development in a regional context could greatly improve management approaches for protecting and restoring lake resources. The goal of this study was to develop an approach using high-resolution aerial photographs to quantify and assess docks as indicators of shoreline development. First, we describe a dock analysis workflow that can be used to quantify the spatial extent of docks using aerial images. Our approach incorporates pixel-based classifiers with object-based techniques to effectively analyze high-resolution digital imagery. Second, we apply the analysis workflow to quantify docks for 4261 lakes managed by the Minnesota Department of Natural Resources. Overall accuracy of the analysis results was 98.4% (87.7% based on View the MathML source) after manual post-processing. The analysis workflow was also 74% more efficient than the time required for manual digitization of docks. These analyses have immediate relevance for resource planning in Minnesota, whereas the dock analysis workflow could be used to quantify shoreline development in other regions with comparable imagery. These data can also be used to better understand the effects of shoreline development on aquatic resources and to evaluate the effects of shoreline development relative to other stressors. Numéro de notice : A2013-389 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.04.006 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.04.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32527 [article]

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Effects of national forest inventory plot location error on forest carbon stock estimation using k-nearest neighbor algorithm / Jaehoon Jung in ISPRS Journal of photogrammetry and remote sensing, vol 81 (July 2013)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 81 (July 2013) . - pp 82 - 92 Titre : Effects of national forest inventory plot location error on forest carbon stock estimation using k-nearest neighbor algorithm Type de document : Article/Communication Auteurs : Jaehoon Jung, Auteur ; Sangpil Kim, Auteur ; Sungchul Hong, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 82 - 92 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] biomasse [Termes IGN] classification barycentrique [Termes IGN] Corée du sud [Termes IGN] erreur aléatoire [Termes IGN] erreur de positionnement [Termes IGN] erreur systématique [Termes IGN] estimation statistique [Termes IGN] image Landsat-TM [Termes IGN] inventaire forestier étranger (données) [Termes IGN] puits de carbone Résumé : (Auteur) This paper suggested simulation approaches for quantifying and reducing the effects of National Forest Inventory (NFI) plot location error on aboveground forest biomass and carbon stock estimation using the k-Nearest Neighbor (kNN) algorithm. Additionally, the effects of plot location error in pre-GPS and GPS NFI plots were compared. Two South Korean cities, Sejong and Daejeon, were chosen to represent the study area, for which four Landsat TM images were collected together with two NFI datasets established in both the pre-GPS and GPS eras. The effects of plot location error were investigated in two ways: systematic error simulation, and random error simulation. Systematic error simulation was conducted to determine the effect of plot location error due to misregistration. All of the NFI plots were successively moved against the satellite image in 360° directions, and the systematic error patterns were analyzed on the basis of the changes of the Root Mean Square Error (RMSE) of kNN estimation. In the random error simulation, the inherent random location errors in NFI plots were quantified by Monte Carlo simulation. After removal of both the estimated systematic and random location errors from the NFI plots, the RMSE% were reduced by 11.7% and 17.7% for the two pre-GPS-era datasets, and by 5.5% and 8.0% for the two GPS-era datasets. The experimental results showed that the pre-GPS NFI plots were more subject to plot location error than were the GPS NFI plots. This study’s findings demonstrate a potential remedy for reducing NFI plot location errors which may improve the accuracy of carbon stock estimation in a practical manner, particularly in the case of pre-GPS NFI data. Numéro de notice : A2013-390 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.04.008 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.04.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32528 [article]

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Development of a 3-D urbanization index using digital terrain models for surface urban heat island effects / Chih-Da Wu in ISPRS Journal of photogrammetry and remote sensing, vol 81 (July 2013)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 81 (July 2013) . - pp. 1 - 11 Titre : Development of a 3-D urbanization index using digital terrain models for surface urban heat island effects Type de document : Article/Communication Auteurs : Chih-Da Wu, Auteur ; Shih-Chun Candice Lung, Auteur ; Jihn-Fa Jan, Auteur Année de publication : 2013 Article en page(s) : pp. 1 - 11 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] données localisées 3D [Termes IGN] étude d'impact [Termes IGN] ilot thermique urbain [Termes IGN] image Terra-MODIS [Termes IGN] index spatial [Termes IGN] milieu urbain [Termes IGN] modèle numérique de terrain [Termes IGN] Taipei (Taïwan) [Termes IGN] Taïwan [Termes IGN] température de surface Résumé : (Auteur)This study assesses surface urban heat island (SUHI) effects during heat waves in subtropical areas. Two cities in northern Taiwan, Taipei metropolis and its adjacent medium-sized city, Yilan, were selected for this empirical study. Daytime and night time surface temperature and SUHI intensity of both cities in five heat wave cases were obtained from MODIS Land-Surface Temperature (LST) and compared. In order to assess SUHI in finer spatial scale, an innovated three-dimensional Urbanization Index (3DUI) with a 5-m spatial resolution was developed to quantify urbanization from a 3-D perspective using Digital Terrain Models (DTMs). The correlation between 3DUI and surface temperatures were also assessed. The results obtained showed that the highest SUHI intensity in daytime was 10.2 °C in Taipei and 7.5 °C in Yilan. The SUHI intensity was also higher than that in non-heat-wave days (about 5 °C) in Taipei. The difference in SUHI intensity of both cities could be as small as only 1.0 °C, suggesting that SUHI intensity was enhanced in both large and medium-sized cities during heat waves. Moreover, the surface temperatures of rural areas in Taipei and Yilan were elevated in the intense heat wave cases, suggesting that the SUHI may reach a plateau when the heat waves get stronger and last longer. In addition, the correlation coefficient between 3DUI and surface temperature was greater than 0.6. The innovative 3DUI can be employed to assess the spatial variation of temperatures and SUHI intensity in much finer spatial resolutions than measurements obtained from remote sensing and weather stations. In summary, the empirical results demonstrated intensified SUHI in large and medium-sized cities in subtropical areas during heat waves which could result in heat stress risks of residents. The innovative 3DUI can be employed to identify vulnerable areas in fine spatial resolutions for formulation of heat wave adaptation strategies. Numéro de notice : A2013-384 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2013.03.009 En ligne : https://doi.org/10.1016/j.isprsjprs.2013.03.009 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=73670 [article]

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