addbuff {terrainr}

Add a uniform buffer around a bounding box for geographic coordinates

Description

add_bbox_buffer calculates the great circle distance both corners of your bounding box are from the centroid and extends those by a set distance. Due to using Haversine/great circle distance, latitude/longitude calculations will not be exact.

set_bbox_side_length is a thin wrapper around add_bbox_buffer which sets all sides of the bounding box to (approximately) a specified length.

Both of these functions are intended to be used with geographic coordinate systems (data using longitude and latitude for position). For projected coordinate systems, a more sane approach is to use sf::st_buffer to add a buffer, or combine sf::st_centroid with the buffer to set a specific side length.

Usage

add_bbox_buffer(data, distance, distance_unit = "meters", error_crs = NULL)

## S3 method for class 'sf'
add_bbox_buffer(data, distance, distance_unit = "meters", error_crs = NULL)

## S3 method for class 'Raster'
add_bbox_buffer(data, distance, distance_unit = "meters", error_crs = NULL)

## S3 method for class 'SpatRaster'
add_bbox_buffer(data, distance, distance_unit = "meters", error_crs = NULL)

set_bbox_side_length(
  data,
  distance,
  distance_unit = "meters",
  error_crs = NULL
)

## S3 method for class 'sf'
set_bbox_side_length(
  data,
  distance,
  distance_unit = "meters",
  error_crs = NULL
)

## S3 method for class 'Raster'
set_bbox_side_length(
  data,
  distance,
  distance_unit = "meters",
  error_crs = NULL
)

## S3 method for class 'SpatRaster'
set_bbox_side_length(
  data,
  distance,
  distance_unit = "meters",
  error_crs = NULL
)

Arguments

data

The original data to add a buffer around. Must be either an sf or SpatRaster object.

distance

The distance to add or to set side lengths equal to.

distance_unit

The units of the distance to add to the buffer, passed to units::as_units.

error_crs

Logical: Should this function error if data has no CRS? If TRUE, function errors; if FALSE, function quietly assumes EPSG:4326. If NULL, the default, function assumes EPSG:4326 with a warning.

Value

An sfc object (from sf::st_as_sfc).

See Also

Other utilities: calc_haversine_distance(), deg_to_rad(), get_centroid(), rad_to_deg()

Examples

df <- data.frame(
  lat = c(44.04905, 44.17609),
  lng = c(-74.01188, -73.83493)
)

df_sf <- sf::st_as_sf(df, coords = c("lng", "lat"))
df_sf <- sf::st_set_crs(df_sf, 4326)

add_bbox_buffer(df_sf, 10)

df <- data.frame(
  lat = c(44.04905, 44.17609),
  lng = c(-74.01188, -73.83493)
)

df_sf <- sf::st_as_sf(df, coords = c("lng", "lat"))
df_sf <- sf::st_set_crs(df_sf, 4326)

set_bbox_side_length(df_sf, 4000)