I am calculating topographic position index (TPI) using SAGA tools for a DEM. TPI looks at the elevation of a raster cell compared to the mean elevation of raster cells in a surrounding neighborhood (ie 100m radius circle). This can be very computationally expensive for a large DEM, if spatial resolution is high, or if you are looking at a large surrounding neighborhood (large radius).

I do not need TPI to be calculated for the entire DEM, though. I only need TPI calculated for specific raster cells (where I had a forestry plot). Is there a way to only calculate TPI for a subset of raster cells?

I have provided links to download:

  • DEM
  • plot buffers (I need to calculate TPI for all raster cells within these polygons.)

https://unh.box.com/s/iohp8z2v7p534xvgpiu50fq1k6574e5e (DEM) https://unh.box.com/s/pv7t8pkkxoofahu0q4r2ogus5s2k7q3e (plot buffer)

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