Suitability Analysis and Fuzzy Logic

Andres Calderon

General overview

Part 1

  • How to deal with diverse cell size and CRS?
  • What about the extent of the study area?
    • i.e. Physical global datasets in degrees (WGS 84) [resolution: 0.9 arcsec]
    • i.e. Socio economic local indicators in metres (Pseudo-mercator) [resolution: 1Km]

Resampling

What we need as output…

  • We need to transform vector layers to raster…
  • We need to use the same spatial resolution (cell size)…
  • We need to clip and align to the same number of columns and rows…

Why?

Raster Algebra!

Part 2

  • How to compare layers from different aspects?
  • Ranges in data? Units? Relationship?
    • i.e. Coronavirus: 106 cases per 10K people.
    • i.e. Temperature: -20.7 celcius degrees.

Linear Fuzzification

What we need as output…

  • Each layer has to be ‘fuzzified’ to a range from 0 to 1 …
  • No more units, just how suitable each aspect is…
  • At this point we should have already dealt with outliers and null values…

Why?

Raster Algebra!

Part 3

  • Assign weights to each layer if needed.
  • Apply fuzzy overlay operations to aggregate the layers.
  • Filter regions with higher potential.

Raster Algebra

What we get as output…

  • A suitability map with values between 0 and 1 (we usually normalize it)…
  • Can be filter out according to a threshold…
  • Can be classified according to a criteria…

General Overview