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基于LIDAR数据的森林参数反演方法研究 总被引：5，自引：0，他引：5
森林结构参数诸如林分平均高、平均冠幅、平均胸径、林分密度、地上生物量等的空间分布对于森林可持续经营管理具有重要意义。以黑河流域祁连山大野口典型森林区为研究区,采用高密度LIDAR小脚印点云数据,在进行单木结构参数提取的基础上,按20 m×20 m大小的网格进行了小区域森林参数反演研究。首先由LIDAR点云数据生成冠层高度模型(Canopy Height Model,CHM),从CHM中估测单株木结构参数树的位置、树高、冠幅。然后采用多元逐步回归分析法建立样地(20 m×20 m)尺度上LIDAR估测的平均树高、冠幅等与实测森林参数(林分平均高、林分算数平均高、平均冠幅、平均胸径、林分密度、地上生物量)之间的关系。结果表明,林分平均高、林分算术平均高、地上生物量的估测方程精度较高,R2均大于0.7,平均冠幅、平均胸径、林分密度的估测方程R2均大于0.5,根据建立的方程得到了森林参数的空间分布图。高密度LIDAR数据可以得到较高精度的森林参数空间分布图,对于森林可持续经营管理以及林相图的更新等具有重要意义,同时对小流域森林水文科学的研究具有重要的应用价值。 相似文献
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一种针对激光雷达强度图像的滤波算法研究 总被引：5，自引：1，他引：5
基于激光雷达数据的特点．提出了一种融合的中值滤波算法。运用此算法和传统的中值滤波算法以及均值算法对激光雷达数据进行了处理，并且使用多种指标对处理的结果进行了比较，证明本算法既保持了传统中值滤波的优点，又改进了对弱边缘目标的保护。 相似文献
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Multiple intertidal bars and troughs, often referred to as ‘ridges and runnels’, are significant features on many macrotidal sandy beaches. Along the coastline of England and Wales, they are particularly prevalent in the vicinity of estuaries, where the nearshore gradient is gentle and a large surplus of sediment is generally present. This paper examines the dynamics of such bar systems along the north Lincolnshire coast. A digital elevation model of the intertidal morphology obtained using LIDAR demonstrates that three to five intertidal bars are consistently present with a spacing of approximately 100 m. The largest and most pronounced bars (height = 0·5–0·8 m) are found around mean sea level, whereas the least developed bars (height = 0·2–0·5 m) occur in the lower intertidal zone. Annual aerial photographs of the intertidal bar morphology were inspected to try to track individual bars from year to year to derive bar migration rates; however, there is little resemblance between concurrent photographs, and ‘resetting’ of the intertidal profile occurs on an annual basis. Three‐dimensional beach surveys were conducted monthly at three locations along the north Lincolnshire coast over a one‐year period. The intertidal bar morphology responds strongly to the seasonal variation in the forcing conditions, and bars are least numerous and flattest during the more energetic winter months. Morphological changes over the monthly time scale are strongly affected by longshore sediment transport processes and the intertidal bar morphology can migrate along the beach at rates of up to 30 m per month. The behaviour of intertidal bars is complex and varies over a range of spatial and temporal scales in response to a combination of forcing factors (e.g. incident wave energy, different types of wave processes, longshore and cross‐shore sediment transport), relaxation time and morphodynamic feedback. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Advances in spatial analytical software allow digital elevation models (DEMs) to be produced which accurately represent landform surface variability and offer an important opportunity to measure and monitor morphological change and sediment transfer across a variety of spatial scales. Many of the techniques presently employed (aerial LIDAR, EDM theodolites, GPS, photogrammetry) suffer coverage or resolution limitations resulting in a trade‐off between spatial coverage and morphologic detail captured. This issue is particularly important when rates of spatial and temporal change are considered for fluvial systems. This paper describes the field and processing techniques required for oblique laser scanning to acquire 0·01 m resolution digital elevation data of an upland reach of the River Wharfe in the UK. The study site is variable with rapidly changing morphology, diverse vegetation and the presence of water, and these are evaluated with respect to laser data accuracy. Scan location, frequency and distance are discussed with reference to survey accuracy and efficiency, and a field protocol is proposed. Scan data cloud merging was achieved with a high degree of precision (sub‐centimetre) and positional data are shown to be very accurate for exposed surfaces. Vegetation and water decrease the accuracy, as the laser pulse is often prevented from reaching the ground surface or is not returned. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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在介绍常用的阈值分割方法的基础上,详述了基于阈值分割的LIDAR建筑物提取方法,对不同阈值分割方法的优越性与实用性进行分析。研究结果表明,阈值法是一种最简单最基本的图像分割方法。全局阈值能快速有效地分割噪声小、比较均匀的图像,动态阈值和c均值模糊阈值分割对不均匀图像能进行较好的分割,其中c均值模糊阈值分割法最佳。 相似文献
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结合影像的LIDAR数据三维建筑物提取 总被引：4，自引：1，他引：3
随着LIDAR技术的出现,三维建筑物的提取也受到越来越多的重视。由于LIDAR数据分布的不连续性和不规律性,直接从机载激光扫描测距数据中进行建筑物提取较为困难。本文提出了一种结合灰度影像的LIDAR数据三维建筑物提取方法,分三个步骤:首先对灰度影像进行建筑物二维提取;然后将处理后影像和LIDAR数据粗匹配,初步确定LI-DAR数据中的三维建筑物区域;最后利用一组阈值操作进行三维建筑物的精确提取。实验结果表明该方法简单实用,适应性强。 相似文献