Raster Points
Raster Points (i.e., Dissemination Area partitioning)
100m by 100m raster points were computed as follows:
 determine the required latitude and longitude increments to move approximately 100m eastwest and 100m northsouth. In Saskatoon, the following values are very close:

 Latitude increment: .00089893575680
 Longitude increment: .00146049608306

 compute 100m x 100m polygons inside a bounding box around Saskatoon, as shown in the following image. NOTE: Must work in lat/lng rather than UTM as the UTM coordinates DO NOT run perfectly eastwest and northsouth in Saskatoon. If the computations are done in UTM, the square raster point polygons appear slightly rotated as shown below.
 Next, each computed raster polygon was compared to all June stop locations. Any raster polygon centroid farther than 1000m from the closest stop was discarded. This greatly reduces the number of raster polygons that must be considered in subsequent calculations (e.g., heatmaps, etc.)
Above: 16,872 raw 100m x 100m raster polygons withing 1000m of a bus stop,
Above: Raster polygons for all DAs. Discarding raster polygons more than 1000m from a bus stop greatly reduces the number of raster points that must be considered in subsequent calculations
Above: Left: Raster polygons computed using lat/lng coordinates. Right: Raster polygons computed using UTM coordinates.
page revision: 5, last edited: 25 Aug 2018 18:39