The streams and catchments are attributed with Pfafstetter codes, based on a hierarchical numbering system, that carry important topological information. For the areas North of 60º, the resolution is 7.5-arc-seconds (the smallest resolution of the GMTED2010 dataset) except for Greenland, where the resolution is 30-arc-seconds.
For most of the globe south of 60º North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. The coverage of the data is global (-180º, 180º, -90º, 90º) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) and the Shuttle Radar Topography Mission (SRTM). The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI) and vector layers of streams and catchment boundaries. af_dem_3_2.zip contains the DEM data for unit 3-2). 3D: This 3D is an imagery of the future.It is a transformation of the 2D images into a 3D representation.
DIGITAL ELEVATION MODEL AND DIGITAL TERRAIN MODEL ZIP FILE
The distribution files have the number of the processing unit appended to the end of the zip file name (e.g. Point cloud: These are basically elevation DSM or Digital terrain model but in a point cloud format.Which means that its points are randomly placed like a cloud. There are 19 processing units for Africa. The DEM data were developed and distributed by processing units. This dataset contains the Digital Elevation Model (DEM) for Africa from the Hydrologic Derivatives for Modeling and Analysis (HDMA) database.
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