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1. #DIGITAL TERRAIN MODEL VS DIGITAL ELEVATION MODEL FOR FREE#
2. #DIGITAL TERRAIN MODEL VS DIGITAL ELEVATION MODEL PRO#

Pfeifer Norbert, in Developments in Earth Surface Processes, 2011 Abstractĭigital terrain models (DTMs) acquired from airborne laser scanning (ALS) are available for many mountainous regions. 8.6) shows that DTM A over predicted the altitude especially in the main channel and badland areas due to a lack of resolution. A comparison of the absolute difference in altitude for both DTMs ( Fig. DTM B has a higher resolution that enables recognition of much smaller geomorphic features, such as erosion rills, gully systems and some badlands that can be detected from the orthomosaic as well. It is not possible to distinguish the badland areas that have been identified on the orthomosaic. Due to the interpolation the land surface is very smooth and does not show any geomorphic details such as the dam, its breach or the gully cut through the sediments. DTM A still allows to recognize main geomorphic features, such as the slope and riverbed, but it is unsuitable for our badland volume analysis. Due to internal algorithms the resolution of the generated DTM generalized to a cell size of at least five times the GSD (in our case: 5 × 3.12 cm per pixel). This is two and a half times the resolution of the DTM B (derived from the UAV imagery): 0.1562 × 0.1562 m per pixel. DTM A (derived from the contour lines) has a resolution of 0.383 × 0.383 m per pixel. As presumed, they differ in their resolution and level of detail.

#DIGITAL TERRAIN MODEL VS DIGITAL ELEVATION MODEL PRO#

#DIGITAL TERRAIN MODEL VS DIGITAL ELEVATION MODEL FOR FREE#

Also, the ASTER GDEM is available for free at resolution of 30 m. As an example, the Copernicus DEM 90 m dataset with global coverage is freely available, the global 30 m dataset as well as the 10 m dataset covering the European area have a restricted access. Usually, models with a coarser resolution are freely available, others must be purchased commercially. Cloud cover and shadows are sometimes a limiting factor as well.įrequency: depending on satellite revisit rate In densely vegetated areas it is not possible to capture the ground and picture the bare Earth’s surface.įor processing with optical satellite imagery, two good quality images from different directions are needed. Spatial accuracy: Copernicus DEM: horizontal and vertical accuracy ranges between max. Supporting data: topographic maps, optical images, etc. For models based on optical data, also two optical images from different angles are combined using Ground Control Points to locate the model. For these models, two radar images from different sensors that are captured at the same time are used and combined. Some models are based on radar data, using InSAR Interferometric synthetic aperture radar data. Two methods are used to derive these types of elevation models. Most of them can be obtained at different resolutions. Often, these terms are interchangeable the term DEM is also widely used as a generic definition to describe DSM and DTM.Currently, various data sets are globally available such as the TanDEM-X, SRTM DEM, ASTER GDEM and the ALOS World 3D. Digital Terrain Models capture the ground and picture the bare Earth’s surface as its reference whereas, Digital Surface Models take into account natural and built surface features such as buildings and trees. Global TanDEM-X Elevation Model (Source: DLR)ĭifferent ways are currently established to model elevation: The Digital Elevation Model (DEM), the Digital Surface Model (DSM) and the Digital Terrain Model (DTM).