successful GIS application, is the reference map to which all other data sets are spatially related. 
DOI not only provides this reference base but also provides a visual picture of all of the 
geographic features required by the user. Many GIS users are satisfied with being able to view 
the photographic data for their area of interest and to interpret those geographic features which 
are of interest to them. Other data themes can be readily associated with any of these features 
and if necessary the feature itself can be digitized directly from the image data. Since the DOI 
forms only one theme or layer in the GIS data base it can be turned on or off as required. The 
zoom function of the GIS provides the capability to enlarge the image in the view up to the limit 
of the image resolution. For example the 1:60,000 source images (2 m pixel resolution) 
produced in Manitoba have been reproduced by LGI as hard copy plot at 1:5,000 scale and can 
be viewed on a high resolution monitor at a 1:2,000 scale. 
DOI provides the user with the full picture which often contains substantially more information 
for the user than an interpreted map and when this picture is combined with other key data sets 
such as land ownership, transportation network and hydrography the user is provided with a 
complete set of geographic framework data. 
MANITOBA EXPERIENCE WITH DOI 
During the feasibility and user requirements studies carried out by LGI for the Manitoba Land 
Related Information System (MLRIS) project in 1989 - 1991 it was recognized that users needed 
a new type of reference map data set in order to develop GIS applications. Firstly the traditional 
digital topographic programs were not funded to level which would provide provincial coverage 
in a short time period. This factor was limiting the ability of potential users to get on with GIS 
developments and was putting an extra cost burden on projects because each one had to create 
it’s own map data. A second aspect which was contributing to inhibited GIS development was 
the fact that digital data which were available often did not meet the needs of the user and 
required substantial rework in order to integrate these data in the GIS solution. 
During LGI’s analysis of GIS business functions, users often sited the need to have access to 
current aerial photography as a means of updating existing maps, for interpreting other data 
layers and for providing geographic reference for other data sets. The prospect of having digital 
aerial photography, spatially corrected and useable directly within the GIS drew a great deal of 
interest in the user community and eventually became an element of the MLRIS concept. 
The MLRIS concept developed by LGI includes the building of a sharable set of land related 
information data sets contained within a computer system designed for distributing these data to 
the user community. Several key graphic layers or themes were identified and these included 
land survey fabric to be used for graphically showing land ownership parcels, digital elevation 
data for topographic analysis, digital orthophoto image data, transportation networks, and 
hydrography networks. All of these layers are developed on the same geodetic reference system 
according to defined standards thereby guaranteeing the ability of users to spatially relate all data 
layers. 
DOI was recommended by LGI as the primary reference layer with three main products; 2 m 
pixel data for agricultural areas, .2 m pixel data for urban areas and 10 m pixel data for resource 
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