`bbox_to_wkt()`

returns a WKT POLYGON string for the given bounding box.
Requires GDAL built with the GEOS library.

## Arguments

- bbox
Numeric vector of length four containing xmin, ymin, xmax, ymax.

- extend_x
Numeric scalar. Distance in units of

`bbox`

to extend the rectangle in both directions along the x-axis (results in`xmin = bbox[1] - extend_x`

,`xmax = bbox[3] + extend_x`

).- extend_y
Numeric scalar. Distance in units of

`bbox`

to extend the rectangle in both directions along the y-axis (results in`ymin = bbox[2] - extend_y`

,`ymax = bbox[4] + extend_y`

).

## Value

Character string for an OGC WKT polygon.
`NA`

is returned if GDAL was built without the GEOS library.

## Examples

```
elev_file <- system.file("extdata/storml_elev.tif", package="gdalraster")
ds <- new(GDALRaster, elev_file, read_only=TRUE)
bbox_to_wkt(ds$bbox())
#> [1] "POLYGON ((323476.071970863 5101871.98303138,327766.071970863 5101871.98303138,327766.071970863 5105081.98303138,323476.071970863 5105081.98303138,323476.071970863 5101871.98303138))"
ds$close()
```