利用机载LiDAR数据提取与分析地裂缝

Extraction and analysis of ground fissures from airborne Li DAR data

机载激光扫描可获取植被茂密地区的数字地形模型(DTM),但将其用于茂密植被覆盖区地裂缝提取方法的研究还不多见。以湖南冷水江市浪石滩为试验区,基于机载Li DAR的激光点云数据,研究了植被覆盖区地裂缝的提取方法,分析了地裂缝的微地貌特征。首先对离散的三维激光点云数据依次进行基于不规则三角网滤波、高程滤波及回波信息强度滤波提取地面点,以保留完整的微地貌微特征;然后构建不规则三角网,反距离加权内插生成数字高程模型(DEM),提取地裂缝识别参数,同时基于最小曲率对地裂缝进行线性探测,提取地裂缝的长度信息,且利用地裂缝剖面信息分析其微特征,结合识别参数分析地裂缝的稳定性。研究结果表明:利用机载Li DAR点云数据提取的地裂缝识别参数,能够确定地裂缝的位置、坡度坡向、长度和深度信息,有助于判定地裂缝的稳定性;在植被较为茂密、地面点密度稀疏的区域,保留一定的低矮植被所提取到的DEM能更好地保留地裂缝的微地貌特征。

Airborne laser scanning （ ALS） data have been used to construct the digital terrain model under dense vegetation, but its reliability for recognition ground fissures in the tropics remains unknown. In this paper, Langshitan located in Lengshuijiang City was selected as the study area, and the method for extracting ground fissures and analyzing micro-topography features based on airborne LiDAR point cloud data in the dense vegetation were studied. First, the point clouds were separated into ground points and non-ground points through adaptive TIN filter method, elevation filter, echo intensity difference filter, to ensure that the bare-earth reserved micro-topography features in the dense vegetation. Second, on the basis of ground data, triangulated irregular network was built to generate digital elevation models by inverse distance weighted interpolation; afterwards, ground fissures identification parameters could be extracted, and then linear detection could be performed by the method of minimum curvature. Finally, ground fissures stability was analyzed by the profile information of LiDAR and identification parameters. The results achieved by the authors have shown that qualitative and quantitative identification parameters extracted by the LiDAR data can determine the location, slope and aspect as well as length and depth information of ground fissures and, on such a basis, ground fissures stability can be determined by the profile information of identification parameters and micro - topography features. It is thus proved that DEM constructed by ground points and low vegetation points could reserve micro-topography features.