High-resolution topography for Digital Terrain Model (DTM) in Keller Peninsula, Maritime Antarctica

Abstract High resolution topography (HRT) surveys is an important tool to model landscapes, especially in zones subjected to strong environmental changes, such as Antarctica, where landform is highly influenced by cryoclasty and permafrost melting. The aim of this work was to obtain a high accurate DTM for Keller Peninsula, Maritime Antarctica. The survey study was assessed in the 2014/2015 and 2015/2016 during the austral summer, by using Terrestrial Laser Scanner (TLS). In order to cover 8 km² of the Peninsula, the TLS equipment was installed in 81 different points. Results of the DTM generated by TLS (hereafter, HRT-DTM), and the terrain variables Aspect, Slope and Hillshade obtained were compared with previous models generated by aerophotographic survey (hereafter, APG-DTM). RMSE for the HRT and APG-DTM were 0.726 and 2.397 m, respectively. Spatial resolution of the DTMs was 0.20 m. Morphometric variables obtained from the two methods presented visual differences on the thematic maps, especially related to the Aspect. Generalization was the main process, whereas interpolation occurred for the HRT survey, being the process of choice for the APG method. A large number of points are obtained by the TLS, providing a dense cloud of points, spatially well-distributed, enabling the generalization process to obtain surface models with high performance.

摘要
高分辨率地形（High Resolution Topography, HRT）测量是模拟地表景观的重要手段，尤其适用于南极等经历剧烈环境变化的区域——该区域的地貌深受冰蚀作用与冻土融化的影响。本研究旨在获取南极半岛海域凯勒半岛的高精度数字地形模型（Digital Terrain Model, DTM）。本次测量于2014/2015及2015/2016年的南半球夏季开展，采用地面激光扫描仪（Terrestrial Laser Scanner, TLS）完成。为覆盖该半岛8平方千米的区域，研究团队在81个不同点位布设了地面激光扫描仪设备。将通过地面激光扫描仪生成的数字地形模型（以下简称HRT-DTM）以及提取得到的坡向、坡度、山体阴影三类地形变量，与此前通过航空摄影测量生成的模型（以下简称APG-DTM）进行对比。两类模型的均方根误差（Root Mean Square Error, RMSE）分别为0.726米与2.397米，空间分辨率均为0.20米。通过两种方法提取得到的地形形态变量在专题地图上呈现出视觉差异，尤以坡向项最为明显。两种方法的核心处理流程存在差异：地面激光扫描测量采用插值处理，而航空摄影测量则以制图综合作为主要处理流程，且制图综合正是航空摄影测量方法的首选处理手段。地面激光扫描仪可获取大量测点，形成空间分布均匀的密集点云，进而通过制图综合流程生成性能优异的地表模型。