Digital elevation models in geospatial applications are becoming more and more essential. Aviation, telecommunications, and mapping activities in forestry and natural resources management, are some of the industries that benefit from the aggregation of elevation info into their daily operations.
In this article, we are going to dive into the very high-resolution elevation products that exist in the geospatial market and how these can assist each industry.
For applications like telecommunications or aviation, a high resolution is necessary. Telecommunication towers, for example, need a clear line of sight between their directional antennae, for clean transmission of their data; and the location of cellphone towers needs to be planned in a way that takes into account the view-shed, to ensure maximum coverage for any given area.
What is the difference between a DSM and DTM?
Discover the different elevation types that are used in Earth Observation and GIS applications.
Planning and visualizing airport approaches and runways generally allows for little error in terms of vertical accuracy for any obstacle, natural or man-made. DEMs provided by Airbus Defence and Space, for example, exceed the SRTM resolution by an order of magnitude: Airbus Elevation 4, which is based on Pléiades stereo and tri-stereo optical data, offers DSM and DTM in worldwide coverage at a 4 meter grid spacing and with a vertical accuracy of 2 meters, which makes it ideal for engineering and infrastructure projects. For larger-scale applications like mapping, terrain analysis or exploration of natural resources, Airbus Elevation 8 offers data based on SPOT 6/7 optical satellite imagery in a horizontal resolution of 8 meters and a vertical accuracy of 3 meters. Also from Airbus, the WorldDEM™ dataset, based on TerraSAR-X and TanDEM-X radar satellite missions, with a grid spacing of 12 meters and a vertical accuracy of 2 meters.
NEXTMap One, another DEM product available via the cloudeo marketplace, provides seamless, void-filled digital elevation data with data coverage at 1-meter resolution.
Both DSM and DTM are available for NEXTMap One, and are ideal for mapping, visualization, and analysis in sectors such as telecommunications, geology, aviation, forestry, natural resources management, infrastructure planning, and emergency response. DTMs from NEXTMap One are commonly used in applications like orthorectification of satellite or aerial optical imagery, but also 3D visualization, watershed analysis, environmental risk analysis, and cartography.
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Which is better – DSM or DTM? Depends on your needs
Since all the data can be plugged into Geographic Information Systems, which can handle global multi-resolution terrain elevation data, they can combine information from multiple sources: Generally speaking, photographic data are more conducive to surface modelling, since they capture the ground cover – natural or human-made – in great detail. Radar and LiDAR missions (the latter mainly airborne), on the other hand, have the ability to detect the actual terrain surface, since their sensing beams can penetrate more easily between trees (even with a full canopy) or structures. But the tradeoff is that these missions are generally limited to smaller areas, like urban environments, where high geospatial accuracy is required.
So which is the best DEM to choose?
That depends on the application and will greatly vary depending on the purpose:
Engineering projects for infrastructure or designing intelligent transportation systems will certainly benefit from terrain models in a higher resolution and a smaller footprint
For telecom purposes, digital surface models with a larger area coverage will be more useful, since line-of-sight planning for longer distances might is crucial.
For use in agriculture and forestry, both models might be equally important: DSM to show vegetation – which may be crucial to assess the health of ecosystems – and DTM for questions of hydrology and soil erosion.
For any business, any organization, or any administration that currently benefits from topographical maps, using DEMs will be even more beneficial.
(Cover Image source: NEXTMap, Intermap)