Canadian Digital Elevation Data
The Canadian Digital Elevation Data (CDED) consists of an ordered array of ground elevations at regularly spaced intervals. The source digital data for CDED at scales of 1:50,000 and 1:250,000 is extracted from the hypsographic and hydrographic elements of the National Topographic Data Base (NTDB) or various scaled positional data acquired from the provinces and territories.
CDED files contain a Western and an Eastern section corresponding to half an National Topographic System (NTS) map sheet. Depending on the latitude of the CDED section, the grid spacing, based on geographic coordinates, vary in resolution from a minimum of 0.75 arc seconds to a maximum 3 arc seconds for the 1:50,000 NTS tiles, and from a minimum of 3 arc seconds to a maximum 12 arc seconds for the 1:250,000 NTS tiles respectively. Ground Elevations are recorded in metres relative to Mean Sea Level (MSL), based on the North American Datum 1983 (NAD83) horizontal reference datum.
CDED are used in geographic information systems (GIS) for land-management applications. CDED plays the same role as contours and relief shading on conventional paper maps but is more powerful analytically. In addition to providing estimated values of elevation points, CDED can be used to determine orientation and the slope of each point when used in GIS applications. CDED can also be used for terrain modeling, for calculating the influence of the terrain on line-of-sight, for radar imaging, for simulating flooding, and similar applications.
Download the CDED Fact Sheet [pdf 5.78 MB]
In some instances, provincial/territorial government agencies are producing CDED of their province/territory under a partnership agreement with Natural Resources Canada.
A CDED produced by a provincial/territorial partner that needs to be joined with the data from a neighbouring partner because the CDED crosses a provincial or territorial boundary is identified with the provincial or territorial acronym of the CDED producer (e.g. 94A01_AB).
Such a CDED is an interim product made available to the user until such time as the CDED from the other contributing partner becomes available and the data sets can be merged into one complete and seamless CDED by Natural Resources Canada.
The data in the interim CDED may extend over the provincial or territorial boundary into the neighbouring province or territory. An overlap of data is necessary for the clip and merge process when joining data sets. Therefore it is recommended that the Geopolitical Boundaries, available on GeoBase, be used to ascertain the location of the provincial border when using an interim CDED.
For more details on Canadian Digital Elevation Data standards and specifications, refer to one of the following documents:
- Canadian Digital Elevation Data, Product Specifications, Edition 3.0 [pdf 198 KB]
- Canadian Digital Elevation Data, Product Specifications, Edition 2.1 [pdf 231 KB]
- Canadian Digital Elevation Data, Product Specifications, Edition 2.0 [pdf 229 KB]
- Canadian Digital Elevation Data, Product Specifications, Edition 1.0 [pdf 208 KB]
- Natural Resources Canada, Canadian Digital Elevation Data, Standards and Specifications, September 2000 [pdf 110 KB]
For a complete description of collection metadata, see the Canadian Digital Elevation Data, Collection Metadata.
Use and Restrictions
Use of the GeoBase data is subject to the Open Government Licence – Canada.
This product is subject to Discrepancies processing provided by the Centre for Topographic Information from Natural Resources Canada. A discrepancy is defined as any deviation from the product's Standards and Specifications. Search for discrepancies related to CDED datasets.
CDED files are distributed in ASCII format and have a .dem file extension. The files are compressed using the PKZIP compression software. Data should be compatible with all applications designed for the United States Geological Survey (USGS) Digital Elevation Model.
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