Data Collection:
With any GIS project I have worked on in the past where data has to be
sought out to be used for a specific software systems, many problems exist.
When using Idrisi 32, the data should be in raster format for analysis
purposes. Unfortunately, there was not a vast amount of Idrisi data readily
available for download off any web site in which I have encountered. To
fully answer my spatial question, I had to use FME universal translator
and importing/exporting tools on many occasions to convert my data to Idrisi
format. For example, my digital elevation model was in ShapeFile format.
Exporting the file as a ASCII file was necessary for it to be readable
in Idrisi. Learning the process of converting the data was also a problem
because required a lot of time and most importantly, a lot of patience
and persistence. As for vectors, when using a vector data set in a raster
based program, points and lines are generalized and attributes are lost
in the conversion (this occurred when i converted my coastline vector file
in Idrisi).
Scale and Projection:
Scale and projection was a problem throughout this project. All Data layers
must be converted to a common reference system (utm-10n) and to a common
X-Y dimension (same number of rows and columns) in order for any of the
MCE analyses employed in this project to be functional.
Quality of Data:
Problems regarding the quality on data and the depth of background research
has been limited by cost ($) and by time (allotted to complete this project.
For example, I found out that good quality statistical data from statistics
Canada regarding detailed census population requires a fee for it to be
obtained (click here
for more details - then scroll down to find out). Another example was,
that a waiting period of 3 days was required to access to data from
Land
Data BC.
Arbitrary
use of Data:
Another area of concern came about when using assumptions like I did in
my project were very error prone. For example, by stating that the
minimum value of urban development near protected watersheds at 100
meters, anything urban development occurring one meter less is not correct,
according to the model. The point being is that there is no perfect way
to set thresholds especially for environmental settings because continuous
variations do occur from one location to another. Related to this fact
is that there is fuzzy logic with setting these thresholds. If a given
site is 99.9999 meters from the protected watershed, that site will not
been counted for (compared to a site located 100.0001 meters from the protected
watershed which will be counted for). In addition, the calculated
weighted factors are to be concerned with because it was my decision alone
that determined the weights of each factor (more errors and uncertainty!).
Decisions were arbitrary, depending on how one perceives the overall biological/physical/chemical
conditions that the North Shore Mountains are exposed to on a daily basis.
Another area of the project to be concerned about is with regard to the weighted factors because it was my decision alone that determined the weights of each factor (more errors and uncertainty!). Therefore, in summary all decisions made by me in this project may not represent real world phenomena.
Limited Complexity:
In terms of assessing urban development suitability ot a given location,
sources of uncertainty and error are inherent. All weight factors regarding
the elevation factor are derived directly from the values within the 25
meter resolution DEM of the North Shore Mountains region. The resolution
of display on a typical computer monitor lacks sufficient detail
to exhibit the subtle changes of the land (i.e. continuous variation) regarding
suitability indexes produced by the Idrisi 32 software (however, the limited
ability of the human mind to process numerous amounts of information from
visual displays is also in part, to blame) . Higher resolution of display
is required for the precise display of the distribution of urban development
suitability across the North Shore Mountains (most single houses in the
Greater Vancouver Metropolitan area are not even 20 meters in width) or
for an specific plot of land of the North Shore Mountains. Thus, the derivation
of slope, and the development of elevation values data processes generates
uncertainty and error. The arbitrary nature of the project and reclassification
schema further increases the uncertainty of results as error occurs during
each of the computational stages (please refer to the cartographic models
for reference). Furthermore, the simple nature of the suitability model
provides only a general spatial distribution of suitable locations
for regions but the results would still require serious field validation.
Additional problems regarding the methodology and the spatial analysis processes employed have been discussed earlier, throughout the project.
Final Discussion
Further studies/extension of this project is highly recommended, particularly in terms of a multi-objective analysis, in which there is more than one scenario for development. For instance by comparing a capitalistic urban development scenario versus a sustainable urban development scenario versus a anti urban development, one could possibly generate a more realistic, optimal suitability urban development model for the North Shore Mountains (A Master Thesis Topic?)
A Personnel Thank You
Many thanks for the many people who gave me support and aid to make leading to the completion of this project:
- Barry Carman (Land data BC)
- Dr. Nadine Schuurman (Assistant Professor - Geographic Information Science - Simon Fraser University)
- Jasper Stoodley (Spatial Information Systems Lab Administrator - Simon Frasar University)
- Aparna
Deshpande (Teaching Assistant - Geographic
Information Science - Simon Frasar University)
- And finally,
to my fellow classmates of the Technical Issues to Geographic Information
Systems (Geography 355-4) course offered at Simon Fraser University during
the 2001-3 semester (you know who you are!)
Please email me at: hkung@sfu.ca regarding any Questions/Queries/Feedback about this project
Thank You For Visiting
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