Full-waveform multispectral lidar to measure vegetation structure and dynamics

用于测量植被结构和动态的全波形多光谱激光雷达

• 批准号: NE/I01702X/1
• 负责人: Francis Danson
• 金额: $ 6.72万
• 依托单位: University of Salford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI01702X%2F1
• 关键词: Full; waveform; multispectral; lidar; measure

Measuring and monitoring the structure of vegetation and seasonal changes in vegetation properties is important in better understanding key processes such as forest growth and the carbon cycle. Traditional direct measurements of important forest structure parameters, such as leaf area index (LAI, a measure of the one-sided leaf area per unit ground area), are extremely time consuming whilst indirect methods, such as those based on hemispherical photographs, rely on a number of assumptions that can introduce significant error. Terrestrial laser scanners (TLS) have the potential to revolutionise measurement of vegetation canopy structure by making rapid, semi-automatic measurements of key structural parameters with unprecedented levels of accuracy. Variables like LAI can be determined by recording the reflected energy from several million laser sample points, providing a permanent 3-dimensional record of vegetation characteristics. However, commercially available TLS are limited by only recording the distance to a small number of objects within the laser beam and by an inability to distinguish leaves and wood. The Salford Advanced Laser Canopy Analyser (SALCA) is a unique, field-portable instrument, developed by the University of Salford and Halo Photonics Ltd, to record the full signal of reflected energy from each laser pulse (full-waveform) and to use two different wavelengths of laser (near and shortwave infrared) to allow discrimination of leaves and woody material. The full-waveform characteristic of the instrument allows retrieval of information on multiple objects within the laser beam and of more detailed information on the nature of objects, such as the proportion of the beam area that they fill. The instrument has the potential to provide information on the structure of forest canopies with unprecedented levels of detail. The SALCA instrument has been tested in laboratory trials, and modelling techniques have been used to understand the recorded response from a range of materials. The proposed work aims to build on this research by conducting field trials of the instrument to assess the potential for measurement of structure in a range of UK forest types, with a focus on accurately quantifying LAI. Algorithms to estimate LAI from SALCA data will be developed and tested by comparison with LAI estimates from hemispherical photographs and commercially available laser scanners. Measurements will be repeated regularly through the spring and early summer to assess the sensitivity of LAI estimates to seasonal changes in the forest canopy and examine the variability in reflectance at the two different laser wavelengths. The proposed work will allow the potential of SALCA for validating estimates of LAI from satellite and aerial sensors to be assessed and will determine the potential of the instrument for monitoring changes in vegetation characteristics over time, which would aid better interpretation of data obtained from carbon flux measurement towers. Knowledge gained from the development and testing of SALCA can contribute to future development and application of multiple wavelength and full-waveform laser scanners on aerial and satellite platforms.

测量和监测植被结构和植被特性的季节性变化，对于更好地了解森林生长和碳循环等关键过程十分重要。传统的直接测量重要的森林结构参数，如叶面积指数（LAI，每单位地面面积的单侧叶面积的测量），是非常耗时的，而间接的方法，如那些基于半球形照片，依赖于一些假设，可以引入重大的误差。地面激光扫描仪（TLS）具有革命性的植被冠层结构测量的潜力，通过快速，半自动测量的关键结构参数，具有前所未有的精度水平。像叶面积指数这样的变量可以通过记录几百万个激光采样点的反射能量来确定，从而提供植被特征的永久三维记录。然而，商业上可用的TLS受到限制，仅记录激光束内少量物体的距离，并且无法区分树叶和木材。索尔福德高级激光冠层分析仪（SALCA）是一种独特的现场便携式仪器，由索尔福德大学和Halo Photonics Ltd开发，用于记录每个激光脉冲（全波形）反射能量的完整信号，并使用两种不同波长的激光（近红外和短波红外）来区分树叶和木质材料。仪器的全波形特性允许检索激光束内多个物体的信息以及物体性质的更详细信息，例如它们填充的光束区域的比例。该文书有可能提供关于森林冠层结构的信息，其详细程度前所未有。SALCA仪器已经在实验室试验中进行了测试，并使用建模技术来了解一系列材料的记录响应。拟议的工作旨在通过对该仪器进行实地试验来评估英国一系列森林类型结构测量的潜力，重点是准确量化LAI。算法估计叶面积指数从SALCA数据将开发和测试比较叶面积指数估计从半球形照片和商用激光扫描仪。测量将定期重复通过春季和初夏，以评估叶面积指数估计的敏感性，在森林冠层的季节性变化，并检查在两个不同的激光波长的反射率的变化。拟议的工作将使SALCA在验证卫星和航空传感器对LAI的估计方面的潜力得到评估，并将确定该仪器在监测植被特征随时间变化方面的潜力，这将有助于更好地解释从碳通量测量塔获得的数据。从SALCA的开发和测试中获得的知识可有助于今后在航空和卫星平台上开发和应用多波长和全波形激光扫描仪。

项目成果

Terrestrial Laser Scanning for Plot-Scale Forest Measurement

• DOI: 10.1007/s40725-015-0025-5
• 发表时间: 2015-12-01
• 期刊: CURRENT FORESTRY REPORTS
• 影响因子: 9.5
• 作者: Newnham, Glenn J.;Armston, John D.;Danson, F. Mark
• 通讯作者: Danson, F. Mark

Testing the Application of Terrestrial Laser Scanning to Measure Forest Canopy Gap Fraction

• DOI: 10.3390/rs5063037
• 发表时间: 2013-06
• 期刊: Remote. Sens.
• 作者: F. A. Ramirez;R. Armitage;F. Danson

Waveform lidar over vegetation: An evaluation of inversion methods for estimating return energy

• DOI: 10.1016/j.rse.2015.04.013
• 发表时间: 2015-07
• 期刊: Remote Sensing of Environment
• 影响因子: 13.5
• 作者: S. Hancock;J. Armston;Zhan Li;R. Gaulton;Philip Lewis;M. Disney;F. Danson;A. Strahler;C. Schaaf;K. Anderson;K. Gaston

Radiometric calibration of a dual-wavelength terrestrial laser scanner using neural networks

使用神经网络对双波长地面激光扫描仪进行辐射校准

• DOI: 10.1080/2150704x.2015.1134843
• 发表时间: 2016
• 期刊: Remote Sensing Letters
• 影响因子: 2.3
• 作者: Schofield L

Developing a dual-wavelength full-waveform terrestrial laser scanner to characterize forest canopy structure

• DOI: 10.1016/j.agrformet.2014.07.007
• 发表时间: 2014-11-01
• 期刊: AGRICULTURAL AND FOREST METEOROLOGY
• 影响因子: 6.2
• 作者: Danson, F. Mark;Gaulton, Rachel;Ramirez, Alberto F.
• 通讯作者: Ramirez, Alberto F.