makeTPI: makeTPI

In geodl: Geospatial Semantic Segmentation with Torch and Terra

makeTPI

Description

Calculate a topographic position index (TPI) from a digital terrain model (DTM) using torch

Usage

makeTPI(
  dtm,
  cellSize = 1,
  innerRadius = 2,
  outerRadius = 10,
  mode = "circle",
  writeRaster = FALSE,
  outName,
  device = "cpu"
)

Arguments

dtm	Input SpatRaster object representing bare earth surface elevations.
cellSize	Resolution of raster grid. Default is 1 m.
innerRadius	= Inner radius when using annulus moving window. Default is 2 cells.
outerRadius	= Outer radius when using a circle or annulus moving window. Default is 10 cells.
mode	Either "circle" or "annulus". Default is "circle".
writeRaster	TRUE or FALSE. Save output to disk. Default is TRUE.
outName	Name of output raster with full file path and extension.
device	"cpu" or "cuda". Use "cuda" for GPU computation. Without using the GPU, implementation will not be significantly faster than using non-tensor-based computation. Defaults is "cpu".

Details

Calculate a topographic position index (TPI) from a digital terrain model (DTM) using torch. TPI is calculated as the center cell elevation minus the mean elevation in a local moving window. Large, positive values indicate local topographic high points while large, negative values indicate topographic low points. Near zero values indicate flat areas. Larger windows can characterize the hillslope position of a cell while smaller windows can capture local topographic variability. Radii are specified using cell counts as opposed to map distance.

Examples

## Not run: 
pth <- "OUTPUT PATH"
dtm <- rast(paste0(pth, "dtm.tif"))
tpiA3_11 <- makeTPI(dtm,cellSize=1,
innerRadius=3,
outerRadius=11,
mode="circle",
writeRaster=TRUE,
outName=paste0(pth, "tpiA3_11.tif"),
device="cuda")

## End(Not run)

geodl documentation built on Nov. 12, 2025, 5:07 p.m.