Methodology
Modus Operandi > Centroids & Density
With all the polygons now containing population data, these polygons can be converted into centroid points (Figure 16). This is as simple as using the XTools extension in ArcGIS to perform the conversion. The resulting points are located in the center of mass of each of the polygons.
Figure 16
Using the density function in Spatial Analyst (Figure 17), a raster layer of population density is produced. Different raster layers resulted depending on the search radius size and output cell size. The search radius is circular and the search is applied to each grid cell. All points that fall within this circle are summed and divided by the area of the circle to get square units. For this analysis, we found that a search radius of 250m with an output cell size of 10 and calculating the results in number of people per hectare best represented population density of the Vancouver CMA because it clearly shows the high density areas of downtown Vancouver and other areas like downtown North Vancouver (Lonsdale corridor) and Central Burnaby (Metrotown). Kernel is selected instead of simple as the density type calculations, as it weighs the points more heavily when they are closer to the center of the centroid. It results in smoother detail of the results.
Figure 17
Methodology:
Area of Study .
Dataset .
Modus Operandi .
Cartographic Model .
Map Discussion
Errors & Limitations
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