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