Find a fixed-width extent from reference points

Find a fixed-width extent from reference points

Usage

hsi_find_extent(
  x,
  points,
  width,
  filename = "",
  overwrite = FALSE,
  insert = FALSE,
  layer = "",
  ...
)

Arguments

x

A SpatRaster with hyperspectral data.

points

A SpatVector with exactly 2 point geometries marking the vertical extent of the region of interest. Must be in the same coordinate space as x.

width

Positive integer. Width of the output extent in pixels.

filename

Character. Output filename. Default "" skips writing.

overwrite

Logical. Overwrite existing file. Default FALSE.

insert

Logical. Insert layer into an existing file. Default FALSE.

layer

Character. Layer name for vector output. Default "".

...

Additional arguments passed to terra::writeVector().

Value

A SpatVector polygon snapped to the grid of x.

Details

The output polygon spans vertically between the two reference points and horizontally by width pixels centered on the mean x-coordinate of the points. The extent is snapped to cell boundaries of x with terra::align() using snap = "near".

The function aborts if the requested extent falls outside the raster bounds. Reduce width or adjust the reference points to fit within x.

See also

hsi_set_extent() to assign physical units to a raster extent.

Other Utilities: hsi_bind_rows(), hsi_subset(), hsi_subset_range(), wavelength_position()

Examples

if (FALSE) { # \dontrun{
x <- terra::rast("REFLECTANCE_testdata.tif")

ends <- terra::vect("spatials.gpkg", layer = "ends")

x_extent <- hsi_find_extent(x, points = ends, width = 100)
x_cropped <- terra::crop(x, x_extent)

x_extent <- hsi_find_extent(
  x,
  points = ends,
  width = 900,
  filename = "spatials.gpkg",
  insert = TRUE,
  layer = "extent"
)
} # }