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首页> 外文期刊>International journal of remote sensing >Polar grid fraction as an estimator of montane tropical forest canopy structure using airborne lidar
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Polar grid fraction as an estimator of montane tropical forest canopy structure using airborne lidar

机译：使用机载激光雷达估算极地栅格分数作为山地热带森林冠层结构的估算器

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摘要

The structure of a forest canopy is the key determinant of light transmission, use and understory availability. Airborne light detection and ranging (LiDAR) has been used successfully to measure multiple canopy structural properties, thereby greatly reducing the fieldwork required to map spatial variation in structure. However, lidar metrics to date do not reflect the full extent of the three-dimensional information available from the data. To this end, we developed a new metric, the polar grid fraction (GRID), based on gridding lidar returns in polar coordinates, in order to more closely match measurements provided by field instruments on leaf area index (LAI), gap fraction (GF) and percentage photosynthetically active radiation transmittance (tPAR). The metric summarizes the arrangement of lidar point returns for a single ground location rather than to an area surrounding the location. Compared with more traditional proportion-based and height percentile-based estimators, the GRID estimator increased validation R2 by 14.5% for GF and 6.0% for tPAR over the next best estimator. LAI was still best estimated with the more traditional statistic based on the proportion of ground returns in 14 m × 14 m moving kernels. By applying the models to a 2 × 2 m grid across the lidar coverage area, extreme values occurred in the estimations of all three response variables when using proportion-based and height percentile-based estimators. However, no extreme values were estimated by models using the GRID estimator, indicating that models based on GRID may be less influenced by spurious data. These results suggest that the GRID estimator is a strong candidate for any project requiring estimates of canopy metrics for large areas.
机译：林冠的结构是透光，使用和林下可用性的关键决定因素。机载光检测和测距（LiDAR）已成功用于测量多个冠层结构特性，从而大大减少了绘制结构空间变化所需的野外工作。但是，迄今为止，激光雷达指标尚未反映出可从数据中获得的三维信息的全部范围。为此，我们基于极坐标中的激光雷达返回栅格化，开发了一种新的度量标准，极地栅格分数（GRID），以便更紧密地匹配现场仪器提供的叶面积指数（LAI），间隙分数（GF）的测量值）和光合有效辐射透射率（tPAR）。该度量标准汇总了单个地面位置而不是该位置周围区域的激光雷达点返回的布置。与更传统的基于比例和基于高度百分位数的估计器相比，GRID估计器将GF的验证R2提高了14.5％，将tPAR的验证R2提高了6.0％。根据14 m×14 m移动内核中地面收益的比例，仍可以使用更传统的统计数据对LAI进行最佳估计。通过将模型应用于整个激光雷达覆盖区域的2×2 m网格，在使用基于比例和基于高度百分比的估算器时，所有三个响应变量的估算都出现了极值。但是，模型没有使用GRID估计器估计任何极值，这表明基于GRID的模型受伪造数据的影响可能较小。这些结果表明，对于需要大面积顶篷度量估计的任何项目，GRID估计器都是不错的选择。

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  • 来源
    《International journal of remote sensing》 |2013年第22期|7464-7472|共9页
  • 作者

    Nicholas R. Vaughn; Gregory P. Asner; Christian P. Giardina;

  • 作者单位

    Institute of Pacific Islands Forestry, USDA Forest Service, Hilo, HI 96720, USA,Department of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305, USA;

    Department of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305, USA;

    Institute of Pacific Islands Forestry, USDA Forest Service, Hilo, HI 96720, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
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