Terrain slope effect on forest height and wood volume estimation from GEDI data
The Global Ecosystem Dynamics Investigation LiDAR (GEDI) is a new full waveform (FW) based LiDAR system that presents a new opportunity for the observation of forest structures globally. The backscattered GEDI signals, as all FW systems, are distorted by topographic conditions within their footprint, leading to uncertainties on the measured forest variables. In this study, we explore how well several approaches based on waveform metrics and ancillary digital elevation model (DEM) data perform on the estimation of stand dominant heights (Hdom) and wood volume (V) across different sites of Eucalyptus plantations with varying terrain slopes. In total, five models were assessed on their ability to estimate Hdom and four models for V. Results showed that the models using the GEDI metrics, such as the height at different energy quantiles with terrain data from the shuttle radar topography mission's (SRTM) digital elevation model (DEM) were still dependent on the topographic slope. For Hdom, an RMSE increase of 14% was observed for data acquired over slopes higher than 20% in comparison to slopes between 10 and 20%. For V, a 74% increase in RMSE was reported between GEDI data acquired over slopes between 0–10% and those acquired over slopes higher than 10%. Next, a model relying on the height at different energy quantiles of the entire waveform (HTn) and the height at different energy quartiles of the bare ground waveform (HGn) was assessed. Two sets of the HGn metrics were generated, the first one was obtained using a simulated waveform representing the echo from a bare ground, while the second one relied on the actual ground return from the waveform by means of Gaussian fitting. Results showed that both the simulated and fitted models provide the most accurate estimates of Hdom and V for all slope ranges. The simulation-based model showed an RMSE that ranged between 1.39 and 1.66 m (between 26.76 and 39.26 m3·ha−1 for V) while the fitting-based method showed an RMSE that ranged between 1.26 and 1.34 m (between 26.78 and 36.29 m3·ha−1 for V). Moreover, the dependency of the GEDI metrics on slopes was greatly reduced using the two sets of metrics. As a conclusion, the effect of slopes on the 25-m GEDI footprints is rather low as the estimation on canopy heights from uncorrected waveforms degraded by a maximum of 1 m for slopes between 20 and 45%. Concerning the wood volume estimation, the effect of slopes was more pronounced, and a degradation on the accuracy (increased RMSE) of a maximum of 20 m3·ha−1 was observed for slopes between 20 and 45%.
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Subjects: | U30 - Méthodes de recherche, K01 - Foresterie - Considérations générales, dendrométrie, télédétection, classe de hauteur (en foresterie), cubage d'arbre, volume, terre en pente, http://aims.fao.org/aos/agrovoc/c_16209, http://aims.fao.org/aos/agrovoc/c_6498, http://aims.fao.org/aos/agrovoc/c_11492, http://aims.fao.org/aos/agrovoc/c_28056, http://aims.fao.org/aos/agrovoc/c_8288, http://aims.fao.org/aos/agrovoc/c_7109, http://aims.fao.org/aos/agrovoc/c_1070, |
Online Access: | http://agritrop.cirad.fr/598455/ http://agritrop.cirad.fr/598455/1/2021Fayad_RS_GEDIslope.pdf |
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U30 - Méthodes de recherche K01 - Foresterie - Considérations générales dendrométrie télédétection classe de hauteur (en foresterie) cubage d'arbre volume terre en pente http://aims.fao.org/aos/agrovoc/c_16209 http://aims.fao.org/aos/agrovoc/c_6498 http://aims.fao.org/aos/agrovoc/c_11492 http://aims.fao.org/aos/agrovoc/c_28056 http://aims.fao.org/aos/agrovoc/c_8288 http://aims.fao.org/aos/agrovoc/c_7109 http://aims.fao.org/aos/agrovoc/c_1070 U30 - Méthodes de recherche K01 - Foresterie - Considérations générales dendrométrie télédétection classe de hauteur (en foresterie) cubage d'arbre volume terre en pente http://aims.fao.org/aos/agrovoc/c_16209 http://aims.fao.org/aos/agrovoc/c_6498 http://aims.fao.org/aos/agrovoc/c_11492 http://aims.fao.org/aos/agrovoc/c_28056 http://aims.fao.org/aos/agrovoc/c_8288 http://aims.fao.org/aos/agrovoc/c_7109 http://aims.fao.org/aos/agrovoc/c_1070 |
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U30 - Méthodes de recherche K01 - Foresterie - Considérations générales dendrométrie télédétection classe de hauteur (en foresterie) cubage d'arbre volume terre en pente http://aims.fao.org/aos/agrovoc/c_16209 http://aims.fao.org/aos/agrovoc/c_6498 http://aims.fao.org/aos/agrovoc/c_11492 http://aims.fao.org/aos/agrovoc/c_28056 http://aims.fao.org/aos/agrovoc/c_8288 http://aims.fao.org/aos/agrovoc/c_7109 http://aims.fao.org/aos/agrovoc/c_1070 U30 - Méthodes de recherche K01 - Foresterie - Considérations générales dendrométrie télédétection classe de hauteur (en foresterie) cubage d'arbre volume terre en pente http://aims.fao.org/aos/agrovoc/c_16209 http://aims.fao.org/aos/agrovoc/c_6498 http://aims.fao.org/aos/agrovoc/c_11492 http://aims.fao.org/aos/agrovoc/c_28056 http://aims.fao.org/aos/agrovoc/c_8288 http://aims.fao.org/aos/agrovoc/c_7109 http://aims.fao.org/aos/agrovoc/c_1070 Fayad, Ibrahim Baghdadi, Nicolas Alcarde Alvares, Clayton Stape, Jose Luiz Bailly, Jean Stéphane Ferraço Scolforo, Henrique Ramos Cegatta, Italo Zribi, Mehrez Le Maire, Guerric Terrain slope effect on forest height and wood volume estimation from GEDI data |
description |
The Global Ecosystem Dynamics Investigation LiDAR (GEDI) is a new full waveform (FW) based LiDAR system that presents a new opportunity for the observation of forest structures globally. The backscattered GEDI signals, as all FW systems, are distorted by topographic conditions within their footprint, leading to uncertainties on the measured forest variables. In this study, we explore how well several approaches based on waveform metrics and ancillary digital elevation model (DEM) data perform on the estimation of stand dominant heights (Hdom) and wood volume (V) across different sites of Eucalyptus plantations with varying terrain slopes. In total, five models were assessed on their ability to estimate Hdom and four models for V. Results showed that the models using the GEDI metrics, such as the height at different energy quantiles with terrain data from the shuttle radar topography mission's (SRTM) digital elevation model (DEM) were still dependent on the topographic slope. For Hdom, an RMSE increase of 14% was observed for data acquired over slopes higher than 20% in comparison to slopes between 10 and 20%. For V, a 74% increase in RMSE was reported between GEDI data acquired over slopes between 0–10% and those acquired over slopes higher than 10%. Next, a model relying on the height at different energy quantiles of the entire waveform (HTn) and the height at different energy quartiles of the bare ground waveform (HGn) was assessed. Two sets of the HGn metrics were generated, the first one was obtained using a simulated waveform representing the echo from a bare ground, while the second one relied on the actual ground return from the waveform by means of Gaussian fitting. Results showed that both the simulated and fitted models provide the most accurate estimates of Hdom and V for all slope ranges. The simulation-based model showed an RMSE that ranged between 1.39 and 1.66 m (between 26.76 and 39.26 m3·ha−1 for V) while the fitting-based method showed an RMSE that ranged between 1.26 and 1.34 m (between 26.78 and 36.29 m3·ha−1 for V). Moreover, the dependency of the GEDI metrics on slopes was greatly reduced using the two sets of metrics. As a conclusion, the effect of slopes on the 25-m GEDI footprints is rather low as the estimation on canopy heights from uncorrected waveforms degraded by a maximum of 1 m for slopes between 20 and 45%. Concerning the wood volume estimation, the effect of slopes was more pronounced, and a degradation on the accuracy (increased RMSE) of a maximum of 20 m3·ha−1 was observed for slopes between 20 and 45%. |
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U30 - Méthodes de recherche K01 - Foresterie - Considérations générales dendrométrie télédétection classe de hauteur (en foresterie) cubage d'arbre volume terre en pente http://aims.fao.org/aos/agrovoc/c_16209 http://aims.fao.org/aos/agrovoc/c_6498 http://aims.fao.org/aos/agrovoc/c_11492 http://aims.fao.org/aos/agrovoc/c_28056 http://aims.fao.org/aos/agrovoc/c_8288 http://aims.fao.org/aos/agrovoc/c_7109 http://aims.fao.org/aos/agrovoc/c_1070 |
author |
Fayad, Ibrahim Baghdadi, Nicolas Alcarde Alvares, Clayton Stape, Jose Luiz Bailly, Jean Stéphane Ferraço Scolforo, Henrique Ramos Cegatta, Italo Zribi, Mehrez Le Maire, Guerric |
author_facet |
Fayad, Ibrahim Baghdadi, Nicolas Alcarde Alvares, Clayton Stape, Jose Luiz Bailly, Jean Stéphane Ferraço Scolforo, Henrique Ramos Cegatta, Italo Zribi, Mehrez Le Maire, Guerric |
author_sort |
Fayad, Ibrahim |
title |
Terrain slope effect on forest height and wood volume estimation from GEDI data |
title_short |
Terrain slope effect on forest height and wood volume estimation from GEDI data |
title_full |
Terrain slope effect on forest height and wood volume estimation from GEDI data |
title_fullStr |
Terrain slope effect on forest height and wood volume estimation from GEDI data |
title_full_unstemmed |
Terrain slope effect on forest height and wood volume estimation from GEDI data |
title_sort |
terrain slope effect on forest height and wood volume estimation from gedi data |
url |
http://agritrop.cirad.fr/598455/ http://agritrop.cirad.fr/598455/1/2021Fayad_RS_GEDIslope.pdf |
work_keys_str_mv |
AT fayadibrahim terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT baghdadinicolas terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT alcardealvaresclayton terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT stapejoseluiz terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT baillyjeanstephane terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT ferracoscolforohenrique terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT ramoscegattaitalo terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT zribimehrez terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata AT lemaireguerric terrainslopeeffectonforestheightandwoodvolumeestimationfromgedidata |
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1792500173229785088 |
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dig-cirad-fr-5984552024-01-29T03:34:08Z http://agritrop.cirad.fr/598455/ http://agritrop.cirad.fr/598455/ Terrain slope effect on forest height and wood volume estimation from GEDI data. Fayad Ibrahim, Baghdadi Nicolas, Alcarde Alvares Clayton, Stape Jose Luiz, Bailly Jean Stéphane, Ferraço Scolforo Henrique, Ramos Cegatta Italo, Zribi Mehrez, Le Maire Guerric. 2021. Remote Sensing, 13 (11):2136, 22 p.https://doi.org/10.3390/rs13112136 <https://doi.org/10.3390/rs13112136> Terrain slope effect on forest height and wood volume estimation from GEDI data Fayad, Ibrahim Baghdadi, Nicolas Alcarde Alvares, Clayton Stape, Jose Luiz Bailly, Jean Stéphane Ferraço Scolforo, Henrique Ramos Cegatta, Italo Zribi, Mehrez Le Maire, Guerric eng 2021 Remote Sensing U30 - Méthodes de recherche K01 - Foresterie - Considérations générales dendrométrie télédétection classe de hauteur (en foresterie) cubage d'arbre volume terre en pente http://aims.fao.org/aos/agrovoc/c_16209 http://aims.fao.org/aos/agrovoc/c_6498 http://aims.fao.org/aos/agrovoc/c_11492 http://aims.fao.org/aos/agrovoc/c_28056 http://aims.fao.org/aos/agrovoc/c_8288 http://aims.fao.org/aos/agrovoc/c_7109 Brésil http://aims.fao.org/aos/agrovoc/c_1070 The Global Ecosystem Dynamics Investigation LiDAR (GEDI) is a new full waveform (FW) based LiDAR system that presents a new opportunity for the observation of forest structures globally. The backscattered GEDI signals, as all FW systems, are distorted by topographic conditions within their footprint, leading to uncertainties on the measured forest variables. In this study, we explore how well several approaches based on waveform metrics and ancillary digital elevation model (DEM) data perform on the estimation of stand dominant heights (Hdom) and wood volume (V) across different sites of Eucalyptus plantations with varying terrain slopes. In total, five models were assessed on their ability to estimate Hdom and four models for V. Results showed that the models using the GEDI metrics, such as the height at different energy quantiles with terrain data from the shuttle radar topography mission's (SRTM) digital elevation model (DEM) were still dependent on the topographic slope. For Hdom, an RMSE increase of 14% was observed for data acquired over slopes higher than 20% in comparison to slopes between 10 and 20%. For V, a 74% increase in RMSE was reported between GEDI data acquired over slopes between 0–10% and those acquired over slopes higher than 10%. Next, a model relying on the height at different energy quantiles of the entire waveform (HTn) and the height at different energy quartiles of the bare ground waveform (HGn) was assessed. Two sets of the HGn metrics were generated, the first one was obtained using a simulated waveform representing the echo from a bare ground, while the second one relied on the actual ground return from the waveform by means of Gaussian fitting. Results showed that both the simulated and fitted models provide the most accurate estimates of Hdom and V for all slope ranges. The simulation-based model showed an RMSE that ranged between 1.39 and 1.66 m (between 26.76 and 39.26 m3·ha−1 for V) while the fitting-based method showed an RMSE that ranged between 1.26 and 1.34 m (between 26.78 and 36.29 m3·ha−1 for V). Moreover, the dependency of the GEDI metrics on slopes was greatly reduced using the two sets of metrics. As a conclusion, the effect of slopes on the 25-m GEDI footprints is rather low as the estimation on canopy heights from uncorrected waveforms degraded by a maximum of 1 m for slopes between 20 and 45%. Concerning the wood volume estimation, the effect of slopes was more pronounced, and a degradation on the accuracy (increased RMSE) of a maximum of 20 m3·ha−1 was observed for slopes between 20 and 45%. article info:eu-repo/semantics/article Journal Article info:eu-repo/semantics/publishedVersion http://agritrop.cirad.fr/598455/1/2021Fayad_RS_GEDIslope.pdf text cc_by info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by/4.0/ https://doi.org/10.3390/rs13112136 10.3390/rs13112136 info:eu-repo/semantics/altIdentifier/doi/10.3390/rs13112136 info:eu-repo/semantics/altIdentifier/purl/https://doi.org/10.3390/rs13112136 |