DEMIX Difference Distribution Histograms

DEMIX seeks to rank 6 global 1 arc sec DEMs (COPDEM, FABDEM, ALOS, NASADEM, SRTM, and ASTER) [1]. It uses the difference between the global DEM and a comparable reference DEM aggregated from 1-5 m lidar-derived UTM DEMs. For each DEM it calculates 5 criteria for describing the elevation, slope, and roughness distributions. Evaluations for each criterion are included in the DEMIX GIS database [2]. These distributions have been used in several presentations [1,5,6]. This data set includes: A CSV format database table listing the 236 tiles used by DEMIX {1], summary statistics for the reference DTM version of the tile, and a link to the PNG graphic with the 3 histograms (if the tile does not have a DSM), and 6 histograms (if the tile has both DSM and DTM). The MICRODEM GIS program [3,4] can display this database, and display the histogram for selected tiles. Filtering of the GIS database allows display of just the histograms for tiles with selected characteristics. DBF version of the same database 236 PNG files with the difference distributions. The histograms cover only the central part of the distributions, which should show a mode close to 0 if the DEM is unbiased. If the histogram does not show a mode for a DEM, it's a clear indication that DEM is not very good in that tile. References: Bielski, C.; López-Vázquez, C.; Guth. P.L.; Grohmann, C.H. and the TMSG DEMIX Working Group, 2023. DEMIX Wine Contest Method Ranks ALOS AW3D30, COPDEM, and FABDEM as Top 1” Global DEMs: https://arxiv.org/pdf/2302.08425.pdf. A revised version of this preprint will be posted soon. Guth, P. L., 2023. DEMIX GIS Database Version 2 (2.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.8062008 . Guth, P.L., 2023, git_microdem: https://github.com/prof-pguth/git_microdem , open source software. Guth, P.L., 2023, MICRODEM: Open-source GIS with a focus on Geomorphometry: https://microdem.org/ , download for Windows-64 installation program and CHM help file. Guth, P.L., Grohmann, C.H., & Trevisani, S., 2023, Geomorphometric and Geospatial Patterns in Differences Between ALOS and COPDEM: Geomorphometry2023. https://doi.org/10.5281/zenodo.8057703 Coming soonDEMIX旨在对6款1弧秒分辨率的全球数字高程模型（DEM，Digital Elevation Model）进行排序，分别为COPDEM、FABDEM、ALOS、NASADEM、SRTM以及ASTER[1]。该方法通过对比全球DEM与由1-5米分辨率激光雷达（lidar）衍生的通用横轴墨卡托（UTM，Universal Transverse Mercator）投影DEM聚合得到的可比参考DEM之间的差值，开展评估。针对每一款DEM，研究人员将计算5项指标以描述其高程、坡度及粗糙度分布特征。各项指标的评估结果已收录于DEMIX地理信息系统（GIS，Geographic Information System）数据库[2]。此类分布特征已在多篇学术报告中被引用[1,5,6]。 本数据集包含： 1. 逗号分隔值（CSV，Comma-Separated Values）格式数据库表，其中列明了DEMIX所使用的236幅影像瓦片[1]，包含该瓦片参考数字地形模型（DTM，Digital Terrain Model）版本的汇总统计信息，同时附带指向PNG格式统计图的链接：若该瓦片仅包含数字地形模型而无数字表面模型（DSM，Digital Surface Model），则统计图包含3组直方图；若该瓦片同时包含数字表面模型与数字地形模型，则统计图包含6组直方图。MICRODEM地理信息系统软件[3,4]可加载该数据库，并支持查看选定瓦片的直方图。通过对该GIS数据库进行筛选，可仅展示符合指定特征的瓦片对应的直方图。 2. 上述数据库的DBF格式副本 3. 236个包含差值分布的PNG格式文件。此类直方图仅覆盖分布的中心区间，若DEM无偏，则其分布众数应接近0。若某款DEM的直方图未呈现众数，则清晰表明该DEM在对应影像瓦片上的表现较差。 参考文献： 1. Bielski, C.; López-Vázquez, C.; Guth. P.L.; Grohmann, C.H. 及TMSG DEMIX工作组，2023年。DEMIX评选方法将ALOS AW3D30、COPDEM与FABDEM列为顶级1弧秒全球数字高程模型：https://arxiv.org/pdf/2302.08425.pdf。该预印本的修订版即将发布。 2. Guth, P. L., 2023. DEMIX GIS数据库版本2 (2.0) [数据集]. Zenodo. https://doi.org/10.5281/zenodo.8062008 . 3. Guth, P.L., 2023, git_microdem: https://github.com/prof-pguth/git_microdem ，开源软件。 4. Guth, P.L., 2023, MICRODEM：专注于地貌学的开源地理信息系统：https://microdem.org/ ，提供Windows-64位安装程序及CHM格式帮助文件下载。 5. Guth, P.L., Grohmann, C.H., & Trevisani, S., 2023, ALOS与COPDEM差值的地貌与地理空间模式：Geomorphometry2023。https://doi.org/10.5281/zenodo.8057703 6. 敬请期待