ハイパースペクトルLiDARにより植生下の土壌特性を可視化(Hyperspectral LiDAR Reveals Soil Properties Beneath Vegetation Canopies)

2026-07-19 中国科学院(CAS)

中国科学院(CAS)航空情報研究所(AIR)の王力教授らは、ハイパースペクトルLiDARを用いることで、植生キャノピー下に隠れた土壌の分光情報を取得し、土壌有機炭素(SOC)や全窒素(TN)を推定できることを示した。研究では3次元放射伝達モデルを用い、受動型ハイパースペクトル画像とハイパースペクトルLiDAR点群を比較した。受動型センサーは植生・枝・地表の反射光が混在するため、植生被覆率が高いほど土壌情報の抽出が困難となる。一方、ハイパースペクトルLiDARはレーザー光が樹冠の隙間を通過して地表からの反射を取得でき、3次元点群と分光情報を同時に取得可能である。点群フィルタリングにより地表反射を抽出した結果、散乱の影響が少ない土壌スペクトルを復元し、SOCは決定係数0.332、TNは0.485で推定できた。本技術は、森林など土壌が露出しない地域における森林・土壌系の三次元モニタリングや土壌特性評価への応用が期待される。

ハイパースペクトルLiDARにより植生下の土壌特性を可視化(Hyperspectral LiDAR Reveals Soil Properties Beneath Vegetation Canopies)
NDVI distributions derived from the hyperspectral imagery, and from the HSL point cloud before and after filtering. (Image by AIR)

<関連情報>

下層土壌のスペクトル取得と特性推定におけるハイパースペクトルLiDARの能力評価 Assessing hyperspectral LiDAR capability for understory soil spectral retrieval and property estimation

Yishuo Hao, Li Wang, Zheng Niu, Yunsheng Dong, Jianying Liu, Guoxu Li, Chang Liu, Jie Bai, Kaiyi Bi
Remote Sensing of Environment  Available online: 22 May 2026
DOI:https://doi.org/10.1016/j.rse.2026.115491

Highlights

  • The potential of HSL for understory soil detection is evaluated using 3D RTM.
  • HSL reduces canopy scattering interference more effectively than passive imaging.
  • HSL shows potential for estimating soil organic carbon and total nitrogen content.

Abstract

Continuous soil monitoring is crucial for agricultural and forestry management and for understanding ecosystem health. However, vegetation canopy limits passive remote sensing in capturing understory soil spectral signatures. The recently developed hyperspectral LiDAR (HSL) technology, capable of providing spectral information at distinct geometric positions, offers new possibilities for understory soil detection. In this study, 3D vegetation-soil scenes were constructed using field measured soil hyperspectral data and customized tree models. The LESS radiative transfer model was employed to simulate HSL point clouds and hyperspectral imagery (HI) under varying vegetation coverage levels. The potential for understory soil spectral retrieval was evaluated from three aspects: radiance intensity, spectral curves, and spectral indices. Results demonstrate that laser pulse echoes are substantially less susceptible to canopy multiple scattering interference compared to passive imaging. Retrieved soil spectral curves exhibited markedly improved fidelity, with mean spectral angles decreasing from >2.3° for HI to<0.2° for HSL. Spectral indices showed stronger consistency with reference spectra, with R2 values increasing from 0.49 for HI to >0.83 for HSL. Furthermore, HSL-derived spectral information demonstrated promising potential for soil property estimation, achieving R2 of 0.332 for soil organic carbon (SOC) and 0.485 for total nitrogen (TN) through partial least squares regression modeling. This study demonstrates that HSL is a promising approach for soil monitoring in vegetated areas without requiring extensive bare soil exposure windows.

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