Seamless composite high resolution Digital Elevation Model (DEM) for the Murray Darling Basin Australia

This collection provides a seamlessly merged, hydrologically robust Digital Elevation Model (DEM) for the Murray Darling Basin (MDB), Australia, at 5 m and 25 m grid cell resolution.

This composite DEM has been created from all the publicly available high resolution DEMs in the Geoscience Australia (GA) elevation data portal Elvis (https://elevation.fsdf.org.au/) as at November 2022. The input DEMs, also sometimes referred to as digital terrain models (DTMs), are bare-earth products which represent the ground surface with buildings and vegetation removed. The DEMs were either from lidar (0.5 to 2 m resolution) or photogrammetry (5 m resolution) and totalled 852 individual DEMs.

The merging process involved ranking the DEMs, pairing the DEMs with overlaps, and adjusting and smoothing the elevations of the lower ranked DEM to make the edge elevations compatible with the higher-ranked DEM. This method is adapted from Gallant 2019 with modifications to work with hundreds of DEMs and have a variable number of gaussian smoothing steps.

Where there were gaps in the high-resolution DEM extents, the Forests and Buildings removed DEM (FABDEM; Hawker et al. 2022), a bare-earth radar-derived, 1 arc-second resolution global elevation model was used as the underlying base DEM. FABDEM is based on the Copernicus global digital surface model.

Additionally, hillshade datasets created from both the 5 m and 25 m DEMs are provided.

Note: the FABDEM dataset is available publicly for non-commercial purposes and consequently the data files available with this Collection are also available with a Creative Commons NonCommercial ShareAlike 4.0 Licence (CC BY-NC-SA 4.0). See https://data.bris.ac.uk/datasets/25wfy0f9ukoge2gs7a5mqpq2j7/license.txt

本数据集为澳大利亚墨累-达令盆地（Murray Darling Basin, MDB）提供了一套无缝融合、水文稳健的数字高程模型（Digital Elevation Model, DEM），其网格单元分辨率为5米和25米。

该复合DEM基于2022年11月澳大利亚地球科学局（Geoscience Australia, GA）高程数据门户Elvis（https://elevation.fsdf.org.au/）中所有公开可用的高分辨率DEM创建而成。输入的DEM有时也被称为数字地形模型（digital terrain models, DTMs），属于裸地产品，即去除建筑物和植被后的地表模型。这些DEM的数据源包括激光雷达（lidar，分辨率0.5至2米）和摄影测量（photogrammetry，分辨率5米），共计852个独立DEM。

融合过程包括对DEM进行排序、对重叠DEM进行配对，以及调整和平滑低排名DEM的高程，使其边缘高程与高排名DEM兼容。该方法改编自Gallant 2019的研究成果，并经过修改以适配数百个DEM的处理需求，同时支持可变数量的高斯平滑步骤。

在高分辨率DEM覆盖范围存在空白的区域，去除森林与建筑物的DEM（Forests and Buildings removed DEM, FABDEM；Hawker等，2022）被用作基础DEM。该模型是基于雷达数据的裸地全球高程模型，分辨率为1角秒，且以哥白尼全球数字表面模型为基础。

此外，本数据集还提供了基于5米和25米DEM生成的山体阴影数据集。

注：FABDEM数据集可公开用于非商业用途，因此本数据集包含的数据文件同样采用知识共享非商业性共享类似4.0许可协议（Creative Commons NonCommercial ShareAlike 4.0 Licence, CC BY-NC-SA 4.0）。详情请参见：https://data.bris.ac.uk/datasets/25wfy0f9ukoge2gs7a5mqpq2j7/license.txt