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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)
[article]
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 pointsRésumé : (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
in ISPRS Journal of photogrammetry and remote sensing > vol 104 (June 2015) . - pp 44 - 52[article]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)
[article]
Titre : Evaluation of Lidar-derived DEMs through terrain analysis and field Type de document : Article/Communication Auteurs : Cody P. Gillin, Auteur ; Scott W. Bailey, Auteur ; Kevin J. McGuire, Auteur ; Stephen P. Prisley, Auteur Année de publication : 2015 Article en page(s) : pp 387 - 396 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] bassin hydrographique
[Termes IGN] crète (ligne)
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] filtre passe-bas
[Termes IGN] modèle numérique de surface
[Termes IGN] pas d'échantillonnage au sol
[Termes IGN] penteRésumé : (auteur) Topographic analysis of watershed-scale soil and hydrological processes using digital elevation models (DEMs) is commonplace, but most studies have used DEMs of 10 m resolution or coarser. Availability of higher-resolution DEMs created from light detection and ranging (lidar) data is increasing but their suitability for such applications has received little critical evaluation. Two different 1 m DEMs were re-sampled to 3, 5, and 10 m resolutions and used with and without a low-pass smoothing filter to delineate catchment boundaries and calculate topographic metrics. Accuracy was assessed through comparison with field slope measurements and total station surveys. DEMs provided a good estimate of slope values when grid resolution reflected the field measurement scale. Intermediate scale DEMs were most consistent with land survey techniques in delineating catchment boundaries. Upslope accumulated area was most sensitive to grid resolution, with intermediate resolutions producing a range of UAA values useful in soil and groundwater analysis. Numéro de notice : A2015-973 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.81.5.387 En ligne : https://doi.org/10.14358/PERS.81.5.387 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80043
in Photogrammetric Engineering & Remote Sensing, PERS > vol 81 n° 5 (May 2015) . - pp 387 - 396[article]Angry birds at altitude / Matthew Wade in GEO: Geoconnexion international, vol 14 n° 1 (January 2015)
[article]
Titre : Angry birds at altitude Type de document : Article/Communication Auteurs : Matthew Wade, Auteur Année de publication : 2015 Article en page(s) : pp 23 - 25 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] accessibilité
[Termes IGN] drone
[Termes IGN] escarpementRésumé : (auteur) Tasked with a large and topographically challenging survey near Quito in Ecuador, Aoc ingeniería’s team used an Ebee UAV for data collection. But the terrain wasn’t the only problem it faced, writes Matthew Wade Numéro de notice : A2015-045 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75226
in GEO: Geoconnexion international > vol 14 n° 1 (January 2015) . - pp 23 - 25[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 062-2015011 SL Revue Centre de documentation Revues en salle Disponible 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)
[article]
Titre : Seeing through shadow: Modelling surface irradiance for topographic correction of Landsat ETM+ data Type de document : Article/Communication Auteurs : Tobias Schulmann, Auteur ; Marwan Katurji, Auteur ; Peyman Zawar-Reza, Auteur Année de publication : 2015 Article en page(s) : pp 14 - 24 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] aérosol
[Termes IGN] albedo
[Termes IGN] correction des ombres
[Termes IGN] montagne
[Termes IGN] Nouvelle-Zélande
[Termes IGN] pente
[Termes IGN] réflectance de surface
[Termes IGN] transfert radiatifRésumé : (Auteur) Despite advances in remote sensing, retrieving surface properties at high resolutions in complex terrain is a major challenge. Slope and aspect as well as the topography surrounding a target impact surface insolation and lead to variability in calculated surface reflectance even for homogeneous land cover. Retrieval of surface reflectance is particularly problematic in case of topographic shading, where the total irradiation at the surface is a combination of diffuse irradiation and terrain-reflected irradiation from nearby slopes. To facilitate the retrieval of surface reflectance from high-resolution optical remote sensing, we have explored the feasibility of using a three dimensional radiative transfer code to simulate gridded surface irradiance for a View the MathML source∼37km2 area in the New Zealand Southern Alps. We have tested the sensitivity of simulated irradiance and calculated surface reflectance both in- and outside shaded areas to atmospheric aerosol content, surface albedo, atmospheric boundary layer structure and different solar spectra. Retrieved surface reflectance has been shown to be highly sensitive to atmospheric aerosols and surface albedo, particularly for areas shaded by topography. Not considering atmospheric aerosols in topographic correction can increase derived surface reflectance by well over 50%, while terrain-reflected irradiance can contribute 40% to surface reflectance in shaded areas, even for wider valleys. Both factors should therefore be considered in topographic correction of satellite imagery, even for relatively aerosol-free atmospheres and low surface albedo. Topographic correction for the whole scene was performed with the model settings resulting in the smallest RMSD between surface reflectivity in shaded and unshaded areas of similar land cover. Topographic correction based on 3D radiative transfer simulations has proven to effectively remove topographic effects and almost equalise derived mean reflectance in- and outside shaded areas. While the effective removal of shadows likely requires a higher dynamic range than Landsat’s ETM+ can offer, we suggest further evaluation of this approach in future studies at other sites and with other sensors. Numéro de notice : A2014-634 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2014.10.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2014.10.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75060
in ISPRS Journal of photogrammetry and remote sensing > vol 99 (January 2015) . - pp 14 - 24[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2015011 RAB Revue Centre de documentation En réserve L003 Disponible Impact of local slope and aspect assessed from LiDAR records on tree diameter in radiata pine (Pinus radiata D. Don) plantations / Hanieh Saremi in Annals of Forest Science, vol 71 n° 7 (October 2014)
[article]
Titre : Impact of local slope and aspect assessed from LiDAR records on tree diameter in radiata pine (Pinus radiata D. Don) plantations Type de document : Article/Communication Auteurs : Hanieh Saremi, Auteur ; L. Kumar, Auteur ; Russell Turner, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 771 - 780 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] biomasse
[Termes IGN] pente
[Termes IGN] Pinus (genre)
[Termes IGN] topographie localeRésumé : (Auteur) Context
Reliable information on tree stem diameter variation at local spatial scales and on the factors controlling it could potentially lead to improved biomass estimation over pine plantations.
Aims
This study addressed the relationship between local topography and tree diameter at breast height (DBH) within two even-aged radiata pine plantation sites in New South Wales, Australia.
Methods
A total of 85 plots were established, and 1,302 trees were sampled from the two sites. Airborne light detection and ranging (LiDAR) was used to derive slope and aspect and to link them to each individual tree.
Results
The results showed a significant relationship between DBH and local topography factors. At both sites, trees on slopes below 20° and on southerly aspects displayed significantly larger DBHs than trees on steeper slopes and northerly aspects. Older trees with similar heights also exhibited a significant relationship between DBH and aspect factor, where greater DBHs were found on southerly aspects.
Conclusions
The observed correlation between tree DBH and LiDAR-derived slope and aspect could contribute to the development of improved biomass estimation approaches in pine plantations. These topographical variables are easily attained with airborne LiDAR, and they could potentially improve DBH predictions in resource inventories (e.g. stand volume or biomass) and support field sampling design.Numéro de notice : A2014-534 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-014-0374-4 Date de publication en ligne : 16/04/2014 En ligne : https://doi.org/10.1007/s13595-014-0374-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74147
in Annals of Forest Science > vol 71 n° 7 (October 2014) . - pp 771 - 780[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 016-2014071 SL Revue Centre de documentation Revues en salle Disponible Active learning in the spatial domain for remote sensing image classification / André Stumpf in IEEE Transactions on geoscience and remote sensing, vol 52 n° 5 tome 1 (May 2014)PermalinkGeostatistical methods for predicting soil moisture continuously in a subalpine basin / Katherine E. Williams in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 4 (April 2014)PermalinkAdaptive algorithm for large scale DTM interpolation from lidar data for forestry applications in steep forested terrain / Almasi S. Maguya in ISPRS Journal of photogrammetry and remote sensing, vol 85 (November 2013)PermalinkDevelopment of a vector-based method for coastal bluffline mapping using LiDAR data and a comparison study in the area of lake Erie / Yunjae Choung in Marine geodesy, vol 36 n° 3 (September - November 2013)PermalinkRéflexions sur l'accessibilité aux châtaigniers et ses conséquences dans la haute vallée de la Tinée (parc national du Mercantour) / Mohamed Ben Jeddou in Géomatique expert, n° 94 (01/09/2013)PermalinkForest 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)PermalinkChallenges and lessons from a wetland LiDAR project: a case study of the Okefenokee Swamp, Georgia, USA / L. Shea Rose in Geocarto international, vol 28 n° 3-4 (June - July 2013)PermalinkImpact of scale and quality of Digital Terrain Models on predictability of seabed terrain types / Lars Erikstad in Marine geodesy, vol 36 n° 1 (January - March 2013)PermalinkPermalinkMultidirectional visibility index for analytical shading enhancement / T. Podobnikar in Cartographic journal (the), vol 49 n° 3 (August 2012)Permalink