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THE HELI-DEM MODEL ESTIMATION

机译:Heli-DEM模型估计

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摘要

Global DEMs are fundamental for global applications and are necessary also at the local scale, in regions where local models are not available. Local DEMs are preferred when they are available and if are characterized by better accuracies and resolutions. In general, two problems arise. Firstly, an interest region could be patched by several partly overlapping DEMs that present similar accuracies and spatial resolutions: they should be merged in a unified model. Moreover, even when the interest region is covered by one unified DEM, local DEMs with better accuracy could be available and should be used to locally improve it. All these problems have been addressed within HELI-DEM project. HELI-DEM (HELvetia-Italy Digital Elevation Model) is a project that has been funded by the European Regional Development Fund (ERDF) within the Italy-Switzerland cooperation program. It started in 2010 and finished at the end of 2013. The involved institutions in the project were Fondazione Politecnico di Milano, Politecnico di Milano, Politecnico di Torino, Regione Lombardia, Regione Piemonte and Scuola Universitaria della Svizzera Italiana. One specific aim of the project was the creation and the publication of a unified Digital Elevation Model for the part of the Alps between Italy and Switzerland. The interest area is prevalently mountainous, with heights that range from about 200 m to 4'600 m. Three low Resolution DTMs (20-25-50 m of resolution) are available that partly overlap and patch the whole project area: they are characterized by accuracies of some meters. Also High Resolution DTMs (1-5 m) are available: they have accuracies of some decimeters but cover limited areas of the project. The various models are available in different reference frames (the European ETRF89 and the Italian Roma40) and are gridded either in cartographic or geographic coordinates. Before merging them, a validation of the input data has been performed in three steps: cross validation of LR DTMs, validation of LR DTMs by HR DTMs and final check by geodetic techniques. The comparisons confirm the accuracy of HR data and the presence of few local anomalies in LR DTMs. Considering the goal of the project and the previous results, two different DTMs have been produced. Both of them cover the whole project area (boundaries: λ=7.80° East and λ=10.70° East, Φ=45.10° North e Φ=46.70° North). They are gridded in ETRF2000 geographical coordinates and their spatial resolution is 2 × 10~(-4) degrees. The former has been obtained by interpolating and merging all the input LR DTMs on a new common grid. This DTM has been called HD-1. HD-1 presents the same local anomalies of the LR DTMs used as input for the interpolation: therefore, at least in areas where better data (HR DTMs) are available, its correction was needed. In order to avoid sharp discontinuities, corrections obtained by HR DTMs have been filtered by a numerical FFT approach before applying them. The result of this correction has been called HD-2. HD-1 and HD-2 have already been published by an open access geoservice.
机译:全球数字高程模型是全球应用的基础,也是必要的也是在当地规模,地区,当地的模型不可用。可用时当地的DEM为佳,如果更好的精度和分辨率的特点。在一般情况下,两个问题出现。他们应该在一个统一的模式合并:首先,感兴趣的区域可以由几个部分重叠的DEM是目前同类的精度和空间分辨率进行修补。此外,即使在关注区域由一个统一的DEM覆盖,数字高程模型当地具有较好的精度可能是可用的,应该用于本地改善。所有这些问题已经HELI-DEM项目中解决。 HELI-DEM(云涛,意大利数字高程模型)是已被意大利,瑞士合作计划中的欧洲区域发展基金(ERDF)资助的一个项目。它开始于2010年和2013年在该项目的参与机构年底完成了基金会米兰理工大学,米兰理工大学,都灵理工大学,伦巴第大区,皮埃蒙特大区和SCUOLA Universitaria德拉SVIZZERA意大利。该项目的一个具体目标是建立和统一的数字高程模型的意大利和瑞士之间的阿尔卑斯山的一部分发布。感兴趣区域是普遍地多山,具有范围从约200微米至4'600米的高度。三个低分辨率的DTM(20-25-50米分辨率的)是可用的部分重叠,修补整个项目区:他们的特点是数米的精度。此外高分辨率的DTM(1-5米)可供选择:他们有一些分米精度,但覆盖项目的有限的地区。各种型号在不同的参考帧(欧洲ETRF89和意大利Roma40)获得,并且在制图或地理坐标网格化两种。 LR的DTM,通过人力资源的DTM和大地测量技术最终检查LR的DTM验证交叉验证:将它们合并之前,输入数据的验证已经分三步进行。该比较确定人力资源数据的准确性和LR的DTM一些地方存在异常的。考虑到项目和以前的结果的目标,两种不同的DTM已经产生。两者覆盖整个项目区(边界:λ= 7.80°东和λ= 10.70°东,Φ= 45.10°北ÊΦ= 46.70°北)。它们在网格ETRF2000地理坐标和它们的空间分辨率为2×10〜(-4)度。前者已通过插值和合并在一个新的共同网格中的所有输入LR的DTM获得。这DTM被称为HD-1。 HD-1呈现用作用于内插输入的LR的DTM的相同的局部异常:因此,至少在其中更好的数据(HR的DTM)是可用的区域,需要其的校正。为了避免明显的不连续性,通过HR的DTM获得校正已经在应用之前过滤通过数值FFT的方法。这种修正的结果一直被称为HD-2。 HD-1和HD-2已经通过开放获取出版geoservice。

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