Create a study area raster grid

Build an empty raster covering the combined extent of one or more spatial objects. Useful for defining the common grid before rasterizing species ranges and fishery footprints.

Usage

create_study_raster(layers, res = 0.01, crs = "EPSG:4326")

Arguments

layers

List of sf, sfc, SpatVector, or SpatRaster objects. The output extent will cover all objects.

res

Numeric vector of length 1 or 2. Cell resolution in units of crs (degrees for lon/lat). Default 0.01 (~1 km at equator).

crs

Character. Coordinate reference system. Default "EPSG:4326".

Value

An empty SpatRaster with the computed extent, resolution, and CRS.

Examples

# Two features in different places: the grid has to cover both.
a <- terra::vect("POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))", crs = "EPSG:4326")
b <- terra::vect("POLYGON ((3 3, 5 3, 5 5, 3 5, 3 3))", crs = "EPSG:4326")

grid <- create_study_raster(list(a, b), res = 0.5)
terra::ext(grid)
#> SpatExtent : 0, 5, 0, 5 (xmin, xmax, ymin, ymax)
dim(grid)              # rows, columns, layers
#> [1] 10 10  1
terra::hasValues(grid) # FALSE: the grid is empty, it only defines geometry
#> [1] FALSE

# Inputs are projected to `crs` before their extents are combined, so a list
# mixing coordinate systems is fine.
create_study_raster(list(a, terra::project(b, "EPSG:3857")), res = 0.5)
#> class       : SpatRaster
#> size        : 10, 10, 1  (nrow, ncol, nlyr)
#> resolution  : 0.5, 0.5  (x, y)
#> extent      : 0, 5, 0, 5  (xmin, xmax, ymin, ymax)
#> coord. ref. : lon/lat WGS 84 (EPSG:4326)