Geoscience
PLEASE NOTE: The DEMSM content has been superseded by the SRTM data from NASA.
Introduction
This web site contains four Digital Elevation Models (DEM) of Manitoba (version DEMSM-1.0, DEMSM-2.0, and Manitoba-1.0, and MB_SRTM), as well as various image files of, or derived from, the DEM. Elevation data derived from 2 metre Digital Ortho Images (DOI) were gridded using the rectangular interpolation method in Vertical Mapper (2.5 within MapInfo 5.5) to generate Version 1.0, 2.0 of the DEM of southern Manitoba and Manitoba-1.0. Although version 1.0 is still downloadable, all southern Manitoba images have been updated to version 2.0 images. The DOIs have been produced since 1991 by Manitoba Land Related Information System (MLRIS), Manitoba Conservation and Linnet - The Land Systems Company (production is ongoing). Production and data specifications are described in detail on the specifications page on this web site. The original DEM data, as well as the DOI files were obtained from Linnet - The Land System Company.
Once the original data were gridded it became evident that there were both missing data tiles and erroneous data that appeared as pits and spikes on the grid file. The missing tiles were patched using data derived from 1:50 000 NTS contour lines, whereas the pits and spikes (generally several anomalous data points) were manually corrected by maintaining surface trends in the surrounding area.
In early 2001, the DEM was expanded with the aid of 1:50 000, and 1: 250 000 NTS contour lines. This new version of the DEM (Version 2.0) covered a much larger area of southern Manitoba, although at a lower resolution where contours were integrated. A third version of the DEM (Manitoba-1.0) also produced in 2001, covered the entire land mass of Manitoba at a cell size of 500 metres. Numerous isolated hills can be seen on this version of the DEM. These hills are a function of the elevation sampling frequency which intermittently intersect, for example, eskers which results in a series of hills rather than a continuous ridge.
In early 2000, an international project spearheaded by the National Geospatial-Intelligence Agency (NGA) and the National Aeronautics and Space Administration (NASA) called the Shuttle Radar Topography Mission (SRTM) began. This 11 day mission obtained elevation data on a near-global scale (56°S to 60°N) to generate the Earth’s most complete high-resolution digital topographic database. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour. Information about the SRTM dataset was obtained from the Nasa Jet Propulsion Laboratory. The Canadian portion of this data was released to the public in 2003, The Manitoba Geological Survey has since compiled this 90 metre data for all of Manitoba (MB_SRTM). This data supersedes all other Manitoba digital elevation data on this website.
File Description
The files contained on this web site for version 1.0, 2.0, and Manitoba were created using MapInfo 5.5, 6.5, and 7.0 and software that works with MapInfo (Vertical Mapper 2.5 and Virtual Frontier 1.0); however, this site contains links to a variety of file formats to accommodate use within different software packages, as described below.
Eight extraordinary examples of landforms visible on the DEM large map are linked to annotated images describing the landforms. These images enhance the 3-Dimensional perspective presented on the DEM by changing the angle from which the landforms are viewed, the angle of the light source and/or by draping the DEM with DOIs.
