Simulating the impact of discrete-return lidar system and survey characteristics over young conifer and broadleaf forests
Simulating the impact of discrete-return lidar system and survey characteristics over young conifer and broadleaf forests
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DOI：
10.1016/j.rse.2010.02.009
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发表时间：
2010-07-15
影响因子：
13.5
通讯作者：
Pfeifer, M.
中科院分区：
文献类型：
--
作者：
Disney, M. I.;Kalogirou, V.;Pfeifer, M.
我们提出了一个基于模型的调查离散返回激光雷达系统的效果和调查特性的信号记录在幼林环境。的Monte Carlo射线跟踪（MCRT）模型的冠层散射被用来研究模型估计的灵敏度激光雷达衍生的冠层高度，h（激光雷达）信号触发方法，冠层结构，足迹大小，采样密度和扫描角度，阔叶树和针叶树冠层的密度变化。详细的3D模型的苏格兰松（樟子松）和白桦（桦）被用来模拟激光雷达响应，最小的假设冠层结构。使用这样的模型允许激光雷达参数对冠层高度检索的影响进行测试，在一系列的条件下，通常不可能在实践中。检索h（激光雷达）一般被认为是低估的“真实”冠层高度，h（冠层），但有例外。信号触发方法的选择导致h（激光雷达），低估h（冠层），桦树和松树分别低估4%和7%（极端情况下高达66%）。林冠结构的变化导致平均低估的h（树冠）的13%，桦树和松树之间的29和48%，这取决于年龄，但在某些情况下，高估高达10%。增加足迹直径从0.1到1米增加检索h（激光雷达）从显着低估h（冠层）的值无法区分的h（冠层）。增加采样密度导致略有增加的值h（激光雷达）接近h（冠层），但不显着。增加扫描角度增加h（激光雷达）高达8%的桦树，和19%的松树在扫描角度为30度。扫描角度的影响是更大的针叶树作为一个结果，在树冠高度变化很大。结果表明，林冠内物理建模（假设）回波之间的相互作用与使用实际激光雷达系统的其他研究中的发现相似，并且这些建模回波可能在很大程度上取决于林冠类型和激光雷达采集特征，以及林冠内物理建模（假设）回波之间的相互作用这些属性。激光脉冲/冠层相互作用的物理模型可以提供冠层内脉冲相互作用的额外信息，但在将其应用于实际调查规划和物流之前需要验证和测试。(C)2010年爱思唯尔公司All rights reserved.
We present a model-based investigation of the effect of discrete-return lidar system and survey characteristics on the signal recorded over young forest environments. A Monte Carlo ray tracing (MCRT) model of canopy scattering was used to examine the sensitivity of model estimates of lidar-derived canopy height, h(lidar) to signal triggering method, canopy structure, footprint size, sampling density and scanning angle, for broadleaf and conifer canopies of varying density. Detailed 3D models of Scots pine (Pinus sylvestris) and Downy birch (Betula pubescens) were used to simulate lidar response, with minimal assumptions about canopy structure. Use of such models allowed the impact of lidar parameters on canopy height retrieval to be tested under a range of conditions typically not possible in practice. Retrieved h(lidar) was generally found to be an underestimate of 'true' canopy height, h(canopy), but with exceptions. Choice of signal triggering method caused h(lidar), to underestimate h(canopy) by similar to 4% for birch and similar to 7% for pine (up to 66% in extreme cases). Variations in canopy structure resulted on average in underestimation of h(canopy) by 13% for birch and between 29 and 48% for pine depending on age, but with over-estimates in some cases of up to 10%. Increasing footprint diameter from 0.1 to 1 m increased retrieved h(lidar) from significant underestimates of h(canopy) to values indistinguishable from h(canopy). Increased sampling density led to slightly increased values of h(lidar) to close to h(canopy), but not significantly. Increasing scan angle increased h(lidar) by up to 8% for birch, and 19% for pine at a scan angle of 30 degrees. The impact of scan angle was greater for conifers as a result of large variation in crown height. Results showed that interactions between physically modelled (hypothetical) within canopy returns are similar to findings made in other studies using actual lidar systems, and that these modelled returns can depend strongly on the type of canopy and the lidar acquisition characteristics, as well as interactions between these properties. Physical models of laser pulse/canopy interactions may provide additional information on pulse interactions within the canopy, but require validation and testing before they are applied to actual survey planning and logistics. (C) 2010 Elsevier Inc. All rights reserved.