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As indicated, each time the basic map was revised, the province 
began from scratch with new aerial photography, 
aerotriangulation, etc. Consequently, little experience in 
updating was acquired over the years. 
3. SPATIAL INFOSTRUCTURE NEEDS AND 
CONSTRAINTS 
The government of New Brunswick recognized the importance 
of information about land, water and related resources to 
manage these valuable resources. In order to establish a 
coherence to the government's efforts as they relate to land 
information management, in 1989 a Land Information Policy 
was established. 
This policy ensures that the collective efforts best support the 
provinces’ need for geographically related information to set 
policies and regulations for land and water use, and for the 
resource management. The Policy establishes the Geographic 
Information Corporations digital 1:10 000 topographic data base 
as the official base on which all other provincial spatially 
referenced data will be founded. This collective data base will 
have to be updated if it is to maintain its usefulness. How will 
it be revised? There are many options. However, funds for 
maintaining collective projects are shrinking. In 1992, the 
Geographic Information Corporation adopted a Pricing Policy 
for its products and services. In the category of existing basic 
products and services that involve only maintenance, updating, 
and marketing expenses, the pricing method is based on the 
recovery of additional costs. In other words, costs for revision 
must not exceed revenues from the digital topographic data 
base. We are therefore obliged to find more cost effective 
methods for revising the infostructure. 
The cooperative model (Hamilton 1976) has always been 
appealing. Given that there are only a few province-wide GIS 
users/producers, it will take some time yet for this model to 
reach full maturity. Furthermore, as demonstrated in 
Figure 2-1, the digital data of the digital topographic data base 
is already over 10 years old in some areas. Some catch-up 
techniques will perhaps have to be devised to update the digital 
topographic data base. In that light a project was undertaken to 
assess the soft colour orthophoto (SCO) product for updating 
the digital topographic data base. 
4. CONCEPT 
The production of most soft orthoimagery and the subsequent 
revision of digital topographic data is essentially the same as the 
traditional mapping approach. In summary it consists of the 
establishment of geodetic control, aerial photography, photo 
control, aerotriangulation, block adjustment, collection of digital 
terrain data, orthophoto production and interactive revision. 
This approach does not lend itself to significant savings. 
However, the concept described below bypasses many 
traditional phases. 
4.1 Geodetic Control 
In New Brunswick over 15 000 geodetic control points have 
been established between the late 60's and the mid 70's. 
Consequently, there is no need for additional control. 
4.2 Aerial Photographs 
In 1992, the Department of Natural Resources and Energy 
undertook a study to decide on the methodology to be used for 
311 
updating the forest inventory. In the first digital forest 
inventory, deciduous species were not included. Because of the 
resurgence of interest in these species, there is a need for them 
to be inventoried in the next forest inventory. In order to study 
the new method of inventorying, a sector of the province that 
contained all arboricultural species was photographed. The 
pilot project’s aerial photographs included colour photography 
at the scale of 1:30 000. 
The results of the study were conclusive and the whole province 
will be photographed with colour photography at the scale of 
1:25 000. 
This aerial photography for the project will be taken in the fall, 
before leaves fell. If the infostructure is to be revised from 
aerial photography the ideal time for taking photographs would 
be before the leaves appear or after they have fallen. However, 
because colour photography will be available for the whole 
province, the use of this photography, if satisfactory, would 
entail no additional aerial photography cost. 
4.3 Photo Control, Aerotriangulation and Adjustment 
The purpose of photo control, aerotriangulation and adjustment 
is to establish control to carry out the relative and absolute 
orientations of each photographic model. As discussed earlier, 
the digital topographic data base will be completed in 1994. 
The question raised was as follows: Can the digital topographic 
data be used as control to generate the soft colour orthophoto? 
If this was successful, costs related to photo control, 
aerotriangulation and adjustment would be eliminated. 
4.4 Digital Elevation Model (DEM) 
During the creation of the digital topographic database, spot 
elevations were collected in an irregular grid, 1 mm to 3 mm 
at photo scale, (1:35 000 photo) depending on the roughness of 
the terrain. Block adjustments were carried out as per the 
1:10 000 map accuracy specifications and the spot heights were 
read to a 0.1 m precision. 
Usually the creation of the DEM is an expensive component in 
the orthophoto process. In New Brunswick the DEM collection 
is near completion. The question now is: Will the investment 
in DEM collection over the last ten years allow the province to 
update the digital topographic base at a reduced cost? 
5. EVALUATION OF THE CONCEPT 
5.1 Partnership 
The contract to evaluate the concept was awarded to Universal 
Systems Limited (USL) of Fredericton. USL worked in close 
collaboration with Northeast Exploration Services Ltd. and 
Geomacadie Services Ltd. Northeast Exploration was given the 
orthophoto production responsibilities and Geomacadie the map 
revision responsibility. 
5.2 Selection of Imagery and its Quality 
Aerial photography flown to produce vector maps can vary in 
quality, within the range of specifications, without having a 
great impact on the data. However, aerial photography for soft 
orthophoto is much less forgiving. The quality of the aerial 
photography used in the project was not the best to produce an 
orthophoto. There was a lot of haze and the shadows were at 
their maximum. The shadows are large because the photograph 
was taken a few minutes from the limit of the minimum solar