,Digital Terrain Model (DTM) is a topographic model of the bare Earth. The data files contain the elevation data of the terrain in a digital format which relates to a rectangular grid. Vegetation, buildings and other cultural features are removed digitally - leaving just the underlying terrain.,

The Copernicus DEM is a Digital Surface Model (DSM) which represents the surface of the Earth including buildings, infrastructure and vegetation. This DSM is derived from an edited DSM named WorldDEM, where flattening of water bodies and consistent flow of rivers has been included. In addition, editing of shore- and coastlines, special features such as airports, and implausible terrain structures has also been applied. The WorldDEM product is based on the radar satellite data acquired during the TanDEM-X Mission, which is funded by a Public Private Partnership between the German State, represented by the German Aerospace Centre (DLR) and Airbus Defence and Space. OpenTopography is providing access to the global 90m (GLO-90) DSM through the public AWS S3 bucket established by Sinergise. Note: In the original datasets, the longitudinal spacing of cells increases as a function of latitude for latitudes north of 50N and south of 50S. See the original documentation for details. In order to keep the pixel dimensions uniform, OpenTopography interpolates data north of 50 degrees latitude and south of -50 degrees latitude in order to output a consistent 90m product. GLO-90 is available on a free basis for the general public under the terms and conditions of the License found here

A digital elevation model (DEM) is a 3D representation of the Earth's surface, created from terrain elevation data. These DEMs were generated from LiDAR and LAS data was gathered for the City of Philadelphia