Methodology
To find out which areas in Vancouver are within 400 metres of a public green space, the type of spatial analysis that I chose to use was a simple buffer. The methodology was as such:
- Because I was using shape files from Open Data Catalogue Vancouver, I first had to convert all the files into IDRISI vector files.
- Then, using the module “INITIAL” and the metadata from the file “Parks”, I created an initial raster that I could use to convert my vector files into raster files.
- I used the module “RASTERVECTOR” to convert the files “Parks”, “Greenways” and “Schools” into one raster file called “Green Spaces”.
- I also needed a raster boundary file so I converted “Neighbourhoods” into a separate raster file called “Boundary” using “RASTERVECTOR”.
- I needed both images to be Boolean so I used “RECLASS” on both “Boundary” and “Green Spaces”. On “Boundary”, all of the Vancouver neighbourhoods were given a value of 1 and the remainder was given a value of 0. On “Green Spaces” all of the different parks, greenways and schools were given a value of 1 and the remainder was given 0.
- Next, I used the “BUFFER” module on “Green Spaces” with a radial distance of 400m. (The buffer zone was given a value of 2, the targets had a value of 1 and everything else was assigned 0)
- Because buffers use Euclidean distance, some of the buffer zones covered areas outside the boundaries of Vancouver. To rectify this, I used the “OVERLAY” module to multiply the “Green Spaces” buffer image by the “Boundary” image to produce a final map.
- To further my analysis, I then used the module “AREA” to find out the total amount of land covered by the boundary file, green spaces and the buffers around the green spaces in metres².
- Finally, I converted my final map to a vector file for final design purposes (because raster maps tend to not look very nice)