Problems Encountered While
Creating
This Project
Home Page
Study Design
Background Research
Data
Acquisition
Data Preparation and Manipulation
Spatial
Analysis
Conclusion
References
This multi-criteria evaluation
encountered a few problems and snags along the way to producing the
final result. One of these was incorrectly defining a projection
instead of just projecting the chosen common projection of UTM Zone
10N for the vector images in ArcGIS. This was fixed because it caused
the multi-criteria evaluation module in Idrisi to not be able to
overlay the data images. Another problem was that when the transit
route data (bus stops and SkyTrain line) was converted to raster in
ArcGIS and then imported to Idrisi it would not work in the
multi-criteria evaluation, due to the extent of the images were
different from the rest of the images. This was solved by importing the
original vector images (bus stop and SkyTrain line) into Idrisi and
using the raster gvrd_landuse3 image to set the parameters for the
vector to raster conversion module in Idrisi. Another problem that
occurred was that not all the images had the same number of rows and
columns in the raster images, and even though they were close they were
not exact so the multi-criteria evaluation module in Idrisi refused to
run. This was solved by manually changing the number of rows and
columns in the initial module applied to the gvrd_landuse3 image, so
they were all the same.
A major problem that occurred with the multi-criteria
evaluation concerned the transit images (bus stops and SkyTrain) and
the railway image. They were initially put into the decision wizard as
images to be made into fuzzy images. The resulting multi-criteria
evaluation image was wrong as pixels appearing as good sites were in
fact wrong, because the resulting image had a pattern that appeared to
be wrong according to the input images and some of the pixels landed over water bodies.
This problem is speculated to be caused by the high values that occurred
in the images that had the distance module applied to them in the macro
modeler. Due to this problem the transit images and the railway image
were turned into constraints, which did end up resulting in a correct
multi-criteria evaluation.
The final result from the multi-criteria evaluation
could have been more accurate and applicable if a shapefile of only
parks was
available for the GVRD instead of the "recreation and protected natural
areas" land use category provided by the GVRD land use data. The final
result could have been more useful if
one of the variables was a layer of school locations in the GVRD was
used, because this was one of the criteria cited by the literature
states in the introduction as a good criteria for skate park location
determination. As well a layer of community centres in the GVRD would
also have been useful. The GVRD land use data that was used for this
project contained a category called institutional which included
schools and community centres, but it also had locations of government
buildings and other inappropriate locations so it was not used.
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