
Open File Report OF99-15

Digital Elevation Model of Southern Manitoba (version 1.0)

compiled by G.L.D. Matile and G. Keller


Introduction

This CD-ROM contains a Digital Elevation Model (DEM) of southern Manitoba, 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 the DEM of southern Manitoba. 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 in the DOIspecs.txt file on this CD-ROM. The original DEM data, as well as the DOI files can be obtained from Linnet - The Land System Company (http://www.linnet.ca).

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.


DEM specifications:
	1) Grid resolution: 100 metres (~4600 x 3200 - not including the R.M. of Consol data to the north)
	2) Vertical accuracy: +/- 3 metres (when compared to a network of several thousand geodetic bench marks)
	3) Projection: NAD83, UTM zone 14
	4) Relief shading: light source from 235° azimuth, inclination 30° from horizontal
	5) Color: represents elevation (200 m, blue to 850 m, red)
	

File Description

The files contained on this CD-ROM were created using MapInfo 5.5 (http://www.mapinfo.com) and software that works with MapInfo (Vertical Mapper 2.5 and Virtual Frontier 1.0, http://www.northwoodgeo.com).  However, this CD-ROM contains a variety of file formats to accommodate use within different software packages, as described below. 

A brief geological tour of the DEM can be found by opening DEMSM.htm in any web browser. Seven areas containing outstanding examples of landforms visible on the DEM 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.

GRID directory: contains two sub-directories; ASCII - contains a generic grid file (DEMSMv1.txt) that can be imported into many GIS software packages, and MapInfo - contains two files (DEMSMv1.tab and DEMSMv1.grd) that can be opened directly into MapInfo.
	
HTML directory: contains a variety of image files (JPG and AVI) that are linked to DEMSM.htm but can also be opened independently using image-handling software such as Corel Draw or Microsoft Paint. 
	
IMAGE directory: contains a TIFF file, that is a high resolution (similar resolution to the DEM) copy of the original DEM that can also be opened into most image-handling software packages.
