CDED (Canadian Digital Elevation Data)

Description

CDED provides gridded digital terrain data for Canada at map scales of 1:50K and 1:250K. The file format for this data is virtually identical to the USGS standard ASCII format, and can be imported into RiverTools as USGS Standard Format. Grid spacing at both scales is based on Geographic coordinates and varies with latitudinal zone (A, B, or C). Zone A consists of all latitudes less than 68 degrees north. Zone B consists of latitudes between 68 and 80 degrees north. Zone C consists of latitudes between 80 and 90 degrees. The spans of tiles are designed so that every tile has 1201 columns and 1201 rows, regardless of map scale or latitude zone.

Grid Information

Coord. System: Geographic decimal degrees, fixed-angle
Cell Size (1:50K):
(arcseconds)
  Zone A Zone B Zone C
X-size: 0.75 1.5 3
Y-size: 0.75 0.75 0.75
Cell Size (1:250K):
(arcseconds)
  Zone A Zone B Zone C
X-size: 3 6 12
Y-size: 3 3 3
Tile Dimensions:
(1:50K and 1:250K, all zones)
1201 columns x 1201 rows
Tile Span (1:50K):
(degrees)
  Zone A Zone B Zone C
Longitude: 1/4 (15') 1/2 (30') 1 (60')
Latitude: 1/4 (15') 1/4 (15') 1/4 (15')
Tile Span (1:250K):
(degrees)
  Zone A Zone B Zone C
Longitude: 1 2 4
Latitude: 1 1 1
Data Type: 2-byte integer, signed
Horizontal Datum: North American Datum 1983 (NAD 83), GRS 1980 ellipsoid
Vertical Datum: Mean Sea Level, Canadian Vertical Geodetic Datum
Vertical Units: meters
Nodata Value: Unknown
Formats: USGS Standard ASCII format

How to Import

Choose Import DEM → USGS Standard ASCII from the File menu and then select the file, which will usually have the filename extension ".dem".

Data Source

Centre for Topographic Information (CTI) of Natural Resources Canada (NRC)

Data Availability

Data at the 1:250K scale is available for the entire country, while data at the 1:50K scale provides only partial coverage, mainly in regions with significant economic activity. DEMs for Canada can now be downloaded from the GeoGratis website hosted by Natural Resources Canada.

Web Site

Natural Resources Canada Main Page: http://www.nrcan.gc.ca/home

Download DEMs from GeoGratis: http://www.geogratis.gc.ca/geogratis/search?lang=en

Center for Topographic Information (Canada): http://www.cits.rncan.gc.ca

Copyright (C) RIVIX, LLC. 1998-2016