makeTPI

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

if (FALSE) { # \dontrun{
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")
} # }