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Digital aerial photogrammetry can efficiently support large-area forest inventories in Norway / Lars Johannes in Forestry, an international journal of forest research, vol 90 n° 5 (December 2017)  

Public [article]  inForestry, an international journal of forest research > vol 90 n° 5 (December 2017) . - pp 710 - 718 Titre : Digital aerial photogrammetry can efficiently support large-area forest inventories in Norway Type de document : Article/Communication Auteurs : Lars Johannes, Auteur ; Johannes Breidenbach, Auteur ; Svein Solberg, Auteur ; Erik Naesset, Auteur ; Rasmus Astrup, Auteur Année de publication : 2017 Article en page(s) : pp 710 - 718 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] biomasse forestière [Termes IGN] hauteur des arbres [Termes IGN] inventaire forestier (techniques et méthodes) [Termes IGN] inventaire forestier étranger (données) [Termes IGN] Norvège [Termes IGN] photogrammétrie aérienne [Termes IGN] semis de points [Termes IGN] surface terrière [Termes IGN] volume en bois Résumé : (Auteur) The use of digital aerial photogrammetry (DAP) for forest inventory purposes has been widely studied and can produce comparable accuracy compared with airborne laser scanning (ALS) in small, homogeneous areas. However, the accuracy of DAP for large scale applications with heterogeneous terrain and forest vegetation has not yet been reported. In this study we examined the accuracy of timber volume, biomass and basal area prediction models based on DAP and national forest inventory (NFI) data on a large area in central Norway. Two separate point clouds were derived from aerial image acquisitions of 2010 and 2013. Vegetation heights were extracted by subtracting terrain elevation derived from ALS. A large number of NFI sample plots (483) measured between 2010 and 2014 were used as reference data to fit linear models for timber volume, biomass and basal area with height metrics derived from the DAP data as explanatory variables. Variables describing the heterogeneous environmental and image acquisition conditions were calculated and their influence on the model accuracy was tested. The results showed that forest parameter prediction using DAP works well when applied to a large area. The model fits of the timber volume, biomass and basal area models were good with R2 of 0.80, 0.81, 0.81 and RMSEs of 41.43 m3 ha−1 (55% of the mean observed value), 32.49 t ha−1 (47%), 5.19 m2 ha−1 (41%), respectively. Only a small proportion of the variation could be attributed to the heterogeneous conditions. The inclusion of the relative sun inclination led to an improvement of the model RMSEs by 2% of the mean observed values. The relatively low cost and stability across large areas make DAP an attractive source of auxiliary information for large scale forest inventories. Numéro de notice : A2017-905 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/forestry/cpx027 En ligne : https://doi.org/10.1093/forestry/cpx027 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93207 [article]

Temporal stability of X-band single-pass InSAR heights in a spruce forest: effects of acquisition properties and season / Svein Solberg in IEEE Transactions on geoscience and remote sensing, vol 53 n° 3 (March 2015)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 3 (March 2015) . - pp 1607 - 1614 Titre : Temporal stability of X-band single-pass InSAR heights in a spruce forest: effects of acquisition properties and season Type de document : Article/Communication Auteurs : Svein Solberg, Auteur ; Dan Johan Weydahl, Auteur ; Rasmus Astrup, Auteur Année de publication : 2015 Article en page(s) : pp 1607 - 1614 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] acquisition de données [Termes IGN] bande X [Termes IGN] biomasse [Termes IGN] données météorologiques [Termes IGN] forêt boréale [Termes IGN] image radar moirée [Termes IGN] image TanDEM-X [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] Norvège [Termes IGN] Picea abies [Termes IGN] stabilité dans le temps [Termes IGN] surveillance forestière Résumé : (Auteur) We investigated the stability of TanDEM-X interferometric synthetic aperture radar (InSAR) heights across eight repeated acquisitions. With InSAR height we mean the height above ground of the scattering phase center. We obtained InSAR heights by subtracting a digital terrain model generated from airborne laser scanning. The acquisitions varied in polarization, normal baseline, and season. The study area was a spruce forest in southeastern Norway. We established 179 field plots within 26 selected forest stands and obtained aboveground biomass (AGB) from field inventory. The InSAR heights were generally stable across the acquisitions as was the relationship between AGB and InSAR height, although systematic and random variations were noted. Two acquisitions had close-to-identical technical properties and weather conditions, and they produced close-to-identical InSAR heights. InSAR heights were fairly stable across a range in temperature and precipitation through spring, summer, and autumn, across a range in baseline values and for both HH and VV polarizations. However, a winter acquisition at temperatures of -7°C had much deeper penetration into the canopy and generated considerably lower InSAR heights and, hence, a very different relationship with biomass. Higher random errors were noted in a cross-pol data set due to lower backscatter and when the normal baseline was very small or very large. A height of ambiguity around 20-50 m appeared to be optimal. Interferometric X-band SAR can be used for monitoring coniferous boreal forests as long as the season and technical properties of the acquisition are kept within certain ranges. Numéro de notice : A2015-139 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2346473 Date de publication en ligne : 28/08/2014 En ligne : https://doi.org/10.1109/TGRS.2014.2346473 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75806 [article]

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Estimating forest biomass from TerraSAR-X stripmap radargrammetry / Svein Solberg in IEEE Transactions on geoscience and remote sensing, vol 53 n° 1 (January 2015)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 1 (January 2015) . - pp 154 - 161 Titre : Estimating forest biomass from TerraSAR-X stripmap radargrammetry Type de document : Article/Communication Auteurs : Svein Solberg, Auteur ; Gertrud Riegler, Auteur ; Philippe Nonin, Auteur Année de publication : 2015 Article en page(s) : pp 154 - 161 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse comparative [Termes IGN] biomasse aérienne [Termes IGN] image TerraSAR-X [Termes IGN] inventaire forestier (techniques et méthodes) [Termes IGN] Norvège [Termes IGN] Picea (genre) [Termes IGN] radargrammétrie Résumé : (Auteur) Radargrammetry has a potential for forest inventories, based on the relationship between the canopy height model (CHM) and the forest variables such as biomass. The objective of this study is to describe the relationship between above-ground biomass and a stripmap TerraSAR-X radargrammetry CHM, with emphasis on accuracy and straightness of the relationship. The study was carried out in a spruce forest in south Norway, comprising biomass data from 145 plots of 250 m2 within 21 selected stands. Above-ground biomass for the plots ranged from 0 to 338 t/ha. We derived a digital surface model (DSM) from six TerraSAR-X stripmap acquisitions by automatic stereo matching. We subtracted a digital terrain model (DTM) from the DSM and obtained a CHM. We assigned the nearest 10 m × 10 m pixel to each field plot. The height of the CHM increased linearly with biomass with 15 t/ha/m. The rmse values were 23 t/ha (18%) at the stand level and 58 t/ha (44%) at the plot level. The tendency of curvilinearity was so weak that it could hardly be distinguished from a straight linear relationship. The straightness of the relationship may enable monitoring of biomass changes without an external DTM as input. A comparison between radargrammetry and interferometric synthetic aperture radar (InSAR) showed that the relationship between the biomass and their respective CHMs was almost identical in terms of parameter estimates. The strength of the relationship was higher with InSAR. By combining ascending and descending pairs followed by editing, the performance of radargrammetry was equally good as with InSAR. Numéro de notice : A2015-028 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2319853 En ligne : https://doi.org/10.1109/TGRS.2014.2319853 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75109 [article]

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