R/st_bbox.R

In lidR: Airborne LiDAR Data Manipulation and Visualization for Forestry Applications

#' Bounding box of a LAS* object
#'
#' Bounding box of a `LAS*` object. `st_bbox()` extends `sf`, and `ext()` extends `terra`. The values returned are similar to their
#' parent functions.
#'
#' @return A `bbox` from sf, or a `SpatExtent` from `terra`.
#'
#' @param obj,x An object of class \code{LAS*}.
#' @param ... unused
#'
#' @export
#' @name st_bbox
#' @importFrom sf st_bbox
#' @importFrom terra ext
#' @md
NULL

#' @export
#' @rdname st_bbox
#' @examples
#' f <- system.file("extdata", "example.las", package="rlas")
#' las <- readLAS(f)
#'
#' st_bbox(las)
#' ext(las)
st_bbox.LAS = function(obj, ...)
{
  xr <- range(obj$X)
  yr <- range(obj$Y)
  bbox <- st_bbox(c(xmin = xr[1], xmax = xr[2], ymin = yr[1], ymax = yr[2]))
  sf::st_crs(bbox) <- st_crs(obj)
  return(bbox)
}

#' @export
#' @rdname st_bbox
st_bbox.LASheader = function(obj, ...)
{
  if (obj[["Number of point records"]] == 0L)
    return(sf::NA_bbox_)

  bbox <- c(obj[["Min X"]], obj[["Min Y"]], obj[["Max X"]], obj[["Max Y"]])
  names(bbox) <- c("xmin", "ymin", "xmax", "ymax")
  crs <- tryCatch(crs <- st_crs(obj), error = function(e) sf::NA_crs_)
  return(sf::st_bbox(bbox, crs = crs))
}

#' @export
#' @rdname st_bbox
st_bbox.LAScatalog = function(obj, ...)
{
  # Workaround to repair LAScatalog v3 and minimize backward incompatibilities with v4
  obj <- lascatalog_v3_repair(obj)
  return(sf::st_bbox(obj@data))
}

#' @export
#' @rdname st_bbox
st_bbox.LAScluster = function(obj, ...)
{
  bb <- as.numeric(obj@bbox)
  names(bb) <- c("xmin", "ymin", "xmax", "ymax")
  bb <- sf::st_bbox(bb)
  sf::st_crs(bb) <- st_crs(obj)
  return(bb)
}

st_bbox.raster_template = function(obj, ...)
{
  bb <- c(obj$xmin, obj$ymin, obj$xmax, obj$ymax)
  names(bb) <- c("xmin", "ymin", "xmax", "ymax")
  bb <- sf::st_bbox(bb)
  sf::st_crs(bb) <- obj$crs
  return(bb)
}

# ==== SPATEXTENT =====

#' @export
#' @rdname st_bbox
setMethod("ext", "LAS", function(x, ...) { .ext(x) })

#' @export
#' @rdname st_bbox
setMethod("ext", "LASheader", function(x, ...) { .ext(x) })

#' @export
#' @rdname st_bbox
setMethod("ext", "LAScatalog", function(x, ...) { .ext(x) })

#' @export
#' @rdname st_bbox
setMethod("ext", "LAScluster", function(x, ...) { .ext(x) })

.ext <- function(x)
{
  bb <- st_bbox(x)
  return(terra::ext(bb$xmin, bb$xmax, bb$ymin, bb$ymax))
}