Edge Effects on Tree Height Retrieval Using X-Band Interferometry

Woodhouse, Iain; Izzawati,; Wallington, E.D.; Turner, D.

doi:10.1109/lgrs.2006.872398

Cited by 12 publications

(22 citation statements)

References 16 publications

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“…Vegetation density is considered a critical parameter for extracting forest canopy height. Although this parameter was not analyzed in this work, according to previous studies, height accuracy was better for dense forest canopy due to few ground returns [17,24]. On the contrary, low vegetation density causes significant ground surface scattering, which can lead to lower average Height scattering phase centers (Hspc), and hence worse height results [17,27].…”

Section: Sample Plotsmentioning

confidence: 89%

“…As incidence angle decreases from far range (FR) to near range (NR), the signal penetration depth becomes greater [17,24,40]. This happens because microwave signals at large incidence angles interact more with the forest canopy layer in comparison with the ground layer.…”

Section: Sample Plotsmentioning

confidence: 99%

“…On a semantic level, recent work focuses on single-pass InSAR data (TanDEM-X) due to the lack of temporal decorrelation [22]. The first studies focused on the height discontinuity at a boundary between a tree canopy and an adjacent clear cut [14,24]. A second approach used the interferometric effective height and its subtraction from a reliable DTM produced from other sources, such as field measurements, Lidar, optical photogrammetry [7,20,21,25].…”

Section: Introductionmentioning

confidence: 99%

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Forest canopy height estimation using double-frequency repeat pass interferometry

Karamvasis

Karathanassi

2015

SPIE Proceedings

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In recent years, many efforts have been made in order to assess forest stand parameters from remote sensing data, as a mean to estimate the above-ground carbon stock of forests in the context of the Kyoto protocol. Synthetic aperture radar interferometry (InSAR) techniques have gained traction in last decade as a viable technology for vegetation parameter estimation. Many works have shown that forest canopy height, which is a critical parameter for quantifying the terrestrial carbon cycle, can be estimated with InSAR. However, research is still needed to understand further the interaction of SAR signals with forest canopy and to develop an operational method for forestry applications. This work discusses the use of repeat pass interferometry with ALOS PALSAR (L band) HH polarized and COSMO Skymed (X band) HH polarized acquisitions over the Taxiarchis forest (Chalkidiki, Greece), in order to produce accurate digital elevation models (DEMs) and estimate canopy height with interferometric processing. The effect of wavelength-dependent penetration depth into the canopy is known to be strong, and could potentially lead to forest canopy height mapping using dual-wavelength SAR interferometry at X-and L-band. The method is based on scattering phase center separation at different wavelengths. It involves the generation of a terrain elevation model underneath the forest canopy from repeat-pass L-band InSAR data as well as the generation of a canopy surface elevation model from repeat pass X-band InSAR data. The terrain model is then used to remove the terrain component from the repeat pass interferometric X-band elevation model, so as to enable the forest canopy height estimation. The canopy height results were compared to a field survey with 6.9 m root mean square error (RMSE). The effects of vegetation characteristics, SAR incidence angle and view geometry, and terrain slope on the accuracy of the results have also been studied in this work.

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Section: Sample Plotsmentioning

confidence: 89%

Section: Sample Plotsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Forest canopy height estimation using double-frequency repeat pass interferometry

Karamvasis

Karathanassi

2015

SPIE Proceedings

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“…Hoekman and Varekamp (2001) showed that high-resolution (1.5 m) C-band interferometric height images can contain large height and displacement errors for individual trees. Woodhouse et al (2006) showed the height underestimation would be severe at the edge of the plantation and its extent and amount depended on the incidence angle, tree height and slope. They also stated the influence of canopy heterogeneity must be taken into account in a natural forest where the discontinuities increase over larger areas within the forest canopy.…”

Section: Discussionmentioning

confidence: 99%

Error analysis and correction for extracting the forest height from airborne C-band interferometric SAR and national elevation datasets

Huang

Crabtree

Swanson

et al. 2010

International Journal of Remote Sensing

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The Interferometric Synthetic Aperture Radar (InSAR) signal is returned from the canopy of the obscuring trees instead of bare ground when land is covered by forests. Therefore, the difference between an InSAR elevation and a bare earth model might contain information on forest height. The objective of this paper was to investigate if the difference between an airborne C-band InSAR from the National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL) and a bare earth model of 1/3 arcsecond National Elevation Datasets can be used for regional forest height estimation. The error sources of vertical offset, uncompensated roll angle, residual vertical bias, and scattering phase centre height conversion were analysed and corrected in this estimation. The results were validated by the leastsquare linear regression analysis between Light Detection and Ranging (LiDAR) and the estimated height at different forest stand sizes within different slope categories. In areas with slopes less than 5 , the correlation coefficients increased when forest stand sizes increased. In the area of slope ranging from 5 to 10 , a similar trend of increasing correlation coefficients with increasing stand size could also be observed, but with smaller corresponding correlation coefficients than those of slope 0-5 . In areas with slopes larger than 10 , the correlation coefficients were very poor. These results indicate the difference between airborne C-band InSAR and the accurate bare earth model has the potential for regional forest height estimation in flat areas with a minimum unit of 3750-5000 m 2 . However, to accurately estimate forest height in a mountainous terrain a solution must be found to correct the significant amount of noise caused by the terrain in these areas.

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“…This modelling approach adopts generic canopies of equally sized objects and provides little direct association with the complex scatterer distribution associated with a natural canopy. Although this model, and the like, produce robust height estimates [19][20][21][22][23][24] there is potential for improvement through a consideration of this structural complexity. To assess the impact of forest vertical structure on interferometric coherence, a more realistic interpretation of canopy extinction should see a variation with respect to the vertical distribution of material within the forest canopy.…”

Section: Introductionmentioning

confidence: 99%

A Lidar-Radar Framework to Assess the Impact of Vertical Forest Structure on Interferometric Coherence

Brolly

Simard

Tang

et al. 2016

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Abstract-In this paper, we present novel modelling approaches to investigate the sensitivity of radar interferometric coherence to variations in the vertical forest canopy profile. We introduce a common framework applicable to model radar microwave extinction and structure from lidar data. To perform this analysis, we make use of interferometric data from the UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar) L-band radar and full waveform lidar data from LVIS (Laser Vegetation Imaging Sensor). The data sets were acquired over the Laurentides Wildlife Reserve forest, Quebec, Canada. A two-fold analysis of the framework to estimate interferometric coherence is undertaken. First, a sensitivity analysis is performed by incorporating lidar waveform Legendre descriptions into two adapted independent polarimetric interferometry models. Second, we examine the effectiveness of using lidar data in this novel way to model radar interferometric coherence. Where appropriate, coherence estimates are obtained using Legendre solutions up to 4 th order and at resolutions up to 75m. The maximum r 2 values between modelled outputs and observed coherence across hh, vv and hv polarisations are shown as 0.51 (p<0.05) and 0.76 (p<0.05) at 25m and 75m pixel resolutions respectively. The introduction of a common framework to combine lidar and radar enables an estimation of the impact of canopy structure on observed interferometric coherence and provides further insight into the feasibility of assuming uniform microwave extinction rates on different scales through forest canopy. The framework's potential lies in its use to assess performance of canopy structure estimates from future spaceborne radar interferometers in synergy with lidar data.

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Edge Effects on Tree Height Retrieval Using X-Band Interferometry

Cited by 12 publications

References 16 publications

Forest canopy height estimation using double-frequency repeat pass interferometry

Forest canopy height estimation using double-frequency repeat pass interferometry

Error analysis and correction for extracting the forest height from airborne C-band interferometric SAR and national elevation datasets

A Lidar-Radar Framework to Assess the Impact of Vertical Forest Structure on Interferometric Coherence

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