ST_TPI — Returns a raster with the calculated Topographic Position Index.
raster ST_TPI(raster rast, integer nband, raster customextent, text pixeltype="32BF" , boolean interpolate_nodata=FALSE
Calculates the Topographic Position Index, which is defined as the folcal mean with radius of one minus the center cell.
This function only supports a focalmean radius of one.
ST_MapAlgebra, ST_TRI, ST_Roughness, ST_Slope, ST_HillShade, ST_Aspect