What is a Digital Elevation Model (DEM)?
Digital Elevation Model. (Also DEM, DTM, Digital Terrain Model). A digital representation of the elevation of locations on the land surface. A DEM is often used in reference to a set of elevation values representing the elvation at points [or pixels] in a rectangular grid on the Earth鈥檚 surface."
Source: McDonnell, Rachael and Karen Kemp. International GIS Dictionary. Geoinformation International, 1995.
DEMs and GIS
GIS software, such as ArcGIS, can be used to manipulate DEMs, such as generating contour lines at the elevation interval of choice. With the ArcScene component of ArcGIS, DEMs can be displayed in 3D.
Canada
- . Scanned digital elevation model data in DEM format derived from elevation data from the National Topographic Database data. Resolution: 30 metres (1:50,000)and 90 metres (1:250,000).
- Digital Elevation Model, DMTI. Extracted from the National Topographic Database 1:50,000. Resolution: 30 metres and 90 metres.
- A digital elevation model of the Canada鈥檚 landmass is a DEM file that covers all of Canada. Resolution: 30 arc-seconds (approximately 1 km) & 300 arc-seconds (approximately 10 km).
United States
- . Highest-resolution, best quality elevation data available across the United States into a seamless raster format. Resolution: Complete coverage at 1 arc-seconds and 1/3 arc-seconds. Partial coverage at 1/9 arc-seconds.
- . Shuttle Radar Topography Mission data of the United States. Resolution: 1 arc-seconds (approx. 30 meters) and 3 arc-seconds (approx. 90 meters).
World
- . SRTM 90 Digital Elevation Data, distributed in 5 degree by 5 degree tiles. Resolution: 3 arc-seconds (approx. 90 metres).
- . Global digital elevation model (DEM). Resolution: 30 arc seconds (approximately 1 kilometer)
- . Global elevation model that includes land and ocean floor topography. Resolution: 2 minutes (approximately 3.7 kilometers).
- Esri Data & Maps. SRTM 90, GTOPO30, and ETOPO2 data on DVD. SRTM 90 data divided by continent.
