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Load and validate observation points against a DEM

Source: R/points.R
gla_load_points.Rd

Loads point locations from a spatial file or sf object, validates them against a DEM, and enriches each point with elevation, projected coordinates, and WGS84 lat/lon. The result is the starting point for all downstream gaplightr workflows.

Usage

gla_load_points(x, dem, drop_na_dem = FALSE, ...)

Arguments

x

Either a file path to any file that sf::read_sf can read, or an sf object containing point geometries. If x contains a point_id column of unique positive integers, those values are used as-is for all downstream file naming; otherwise sequential IDs are assigned automatically.

dem

Either a file path to a DEM raster file, or a SpatRaster object

drop_na_dem

Logical. If FALSE (default), points falling on NoData cells in the DEM cause an error. If TRUE, those points are dropped with a warning and processing continues with the remaining points.

...

Additional arguments passed to sf::read_sf() when x is a file path

Details

This function performs strict validation:

  • Geometry type must be POINT

  • CRS must be defined and projected (not geographic lat/lon)

  • Point and DEM CRS must match exactly

  • All points must fall within DEM spatial extent

  • Points on NoData cells error by default; set drop_na_dem = TRUE to drop them with a warning instead

Point IDs

Every point is assigned a point_id, a positive integer used to name all downstream output files (LAS clips, horizon CSVs, fisheye photos). If x does not contain a point_id column, sequential IDs are assigned automatically (1, 2, 3, ...). To use your own IDs (for example to preserve cached outputs across re-runs, or to match an existing site numbering scheme), include a point_id column containing unique positive integers before calling this function.

Examples

# \donttest{
  points_path <- system.file("extdata", "points.geojson", package = "gaplightr")
  dem_path <- system.file("extdata", "dem.tif", package = "gaplightr")
  points <- gla_load_points(points_path, dem_path)
#> Assigning sequential point_id (1 to 3).
# }

# \donttest{
  # Supply your own point_id values to keep cached outputs stable across
  # re-runs or to match an existing site numbering scheme.
  dem_path <- system.file("extdata", "dem.tif", package = "gaplightr")
  my_points <- sf::st_read(
    system.file("extdata", "points.geojson", package = "gaplightr"),
    quiet = TRUE
  )
  my_points$point_id <- c(101L, 202L, 303L)  # user-defined IDs
  points <- gla_load_points(my_points, dem_path)
#> Using existing point_id column (3 point(s)).
# }