Create Tiled GBIF Geometry Queries — make

Divide a study extent into a set of smaller POLYGON() query strings that can be used with the GBIF geometry parameter.

Usage

make_tiles(geo, ntiles, sext = TRUE)

Arguments

geo: Spatial extent or geometry. Used to define the study area. Accepted classes are Extent, SpatExtent, SpatialPolygon, SpatialPolygonDataFrame, SpatVector, and sf. If NULL, the whole globe is used.
ntiles: Numeric. Approximate number of tiles to create.
sext: Logical. Should the corresponding SpatExtent objects also be returned?

Value

If sext = TRUE, a list containing WKT POLYGON() strings and matching SpatExtent objects. Otherwise, a vector of WKT POLYGON() strings.

Details

The input extent is converted into a regular grid of smaller query polygons. This is mainly intended to support tiled GBIF downloads when large extents would otherwise return too many records in a single query.

References

Chauvier, Y., Thuiller, W., Brun, P., Lavergne, S., Descombes, P., Karger, D. N., ... & Zimmermann, N. E. (2021). Influence of climate, soil, and land cover on plant species distribution in the European Alps. Ecological monographs, 91(2), e01433. 10.1002/ecm.1433

Examples

# Load the European Alps Extent
shp.path <- paste0(
  system.file(package = "gbif.range"), 
  "/extdata/shp_lonlat.shp"
)
shp.lonlat <- terra::vect(shp.path)
 
# Apply the function to divide the extent in ~20 fragments
mt <- make_tiles(geo = shp.lonlat, ntiles = 20, sext = TRUE)