ogr_reproject: Reproject a vector layer
In gdalraster: Bindings to 'GDAL'

ogr_reproject

R Documentation

Reproject a vector layer

Description

ogr_reproject() reprojects the features of a vector layer to a different spatial reference system and writes the new layer to a specified output dataset. The output may be in a different vector file format than the input dataset. A source SRS definition must be available in the source layer for reprojection to occur.

Usage

ogr_reproject(
  src_dsn,
  src_layer,
  out_dsn,
  out_srs,
  out_fmt = NULL,
  overwrite = FALSE,
  append = FALSE,
  nln = NULL,
  nlt = NULL,
  dsco = NULL,
  lco = NULL,
  dialect = NULL,
  spat_bbox = NULL,
  src_open_options = NULL,
  progress = FALSE,
  add_cl_arg = NULL,
  return_obj = TRUE
)

Arguments

`src_dsn`	Character string. The filename or database connection string specifying the vector data source containing the input layer.
`src_layer`	Character string. The name of the input layer in `src_dsn` to reproject. Optionally can be given as an SQL SELECT statement to be executed against `src_dsn`, defining the source layer as the result set. May also be given as empty string (`""`), in which case the first layer by index will be used (mainly useful for single-layer file formats such as ESRI Shapefile).
`out_dsn`	Character string. The filename or database connection string specifying the vector data source to which the output layer will be written.
`out_srs`	Character string specifying the output spatial reference system. May be in WKT format or any of the formats supported by `srs_to_wkt()`.
`out_fmt`	Optional character string giving the GDAL short name of the output dataset format. Only used if `out_dsn` needs to be created. Generally can be `NULL` in which case the format will be guessed from the file extension.
`overwrite`	Logical value. `TRUE` to overwrite the output layer if it already exists. Defaults to `FALSE`.
`append`	Logical value. `TRUE` to append to the output layer if it already exists. Defaults to `FALSE`.
`nln`	Optional character string giving an alternate name to assign the new layer. By default, `src_layer` is used, but `nln` is required if `src_layer`is a SQL SELECT statement.
`nlt`	Optional character string to define the geometry type for the output layer. Mainly useful when `nlt = PROMOTE_TO_MULTI` might be given to automatically promote layers that mix polygon / multipolygons to multipolygons, and layers that mix linestrings / multilinestrings to multilinestrings. Can be useful when converting shapefiles to PostGIS and other output formats that implement strict checks for geometry types.
`dsco`	Optional character vector of format-specific creation options for `out_dsn` (`"NAME=VALUE"` pairs). Should only be used if `out_dsn` does not already exist.
`lco`	Optional character vector of format-specific creation options for the output layer (`"NAME=VALUE"` pairs). Should not be used if appending to an existing layer.
`dialect`	Optional character string specifying the SQL dialect to use. The OGR SQL engine (`"OGRSQL"`) will be used by default if a value is not given. The `"SQLite"` dialect can also be use. Only relevant if `src_layer` is given as a SQL SELECT statement.
`spat_bbox`	Optional numeric vector of length four specifying a spatial bounding box (xmin, ymin, xmax, ymax), in the SRS of the source layer. Only features whose geometry intersects `spat_bbox` will be selected for reprojection.
`src_open_options`	Optional character vector of dataset open options for `src_dsn` (format-specific `"NAME=VALUE"` pairs).
`progress`	Logical value, `TRUE` to display progress on the terminal. Defaults to `FALSE`. Only works if the input layer has "fast feature count" capability.
`add_cl_arg`	Optional character vector of additional command-line arguments to be passed to `ogr2ogr()` (see Note).
`return_obj`	Logical value, `TRUE` to return an object of class `GDALVector` open on the output layer (the default).

Details

ogr_reproject() is a convenience wrapper to perform vector reprojection via ogr2ogr(), which in turn is an API binding to GDAL's ogr2ogr command-line utility.

Value

Upon successful completion, an object of class GDALVector is returned by default (if return_obj = TRUE), or logical TRUE is returned (invisibly) if return_obj = FALSE. An error is raised if reprojection fails.

Note

For advanced use, additional command-line arguments may be passed to ogr2ogr() in add_cl_arg (e.g., advanced geometry and SRS related options). Users should be aware of possible implications and compatibility with the arguments already implied by the parameterization of ogr_reproject().

The function will attempt to create the output datasource if it does not already exist. Some formats (e.g., PostgreSQL) do not support creation of new datasets (i.e., a database within PostgreSQL), but output layers can be written to an existing database.

Examples

# MTBS fire perimeters
f <- system.file("extdata/ynp_fires_1984_2022.gpkg", package = "gdalraster")
(mtbs <- new(GDALVector, f, "mtbs_perims"))

mtbs$getSpatialRef() |> srs_is_projected()  # TRUE

# YNP boundary
f <- system.file("extdata/ynp_features.zip", package = "gdalraster")
ynp_dsn <- file.path("/vsizip", f, "ynp_features.gpkg")
(bnd <- new(GDALVector, ynp_dsn, "ynp_bnd"))

bnd$getSpatialRef() |> srs_is_projected()  # FALSE

# project the boundary to match the MTBS layer
out_dsn <- tempfile(fileext = ".gpkg")
(bnd_mtsp <- ogr_reproject(ynp_dsn, "ynp_bnd", out_dsn, mtbs$getSpatialRef()))

bnd_mtsp$getFeatureCount()

plot(bnd_mtsp$getNextFeature(), col = "wheat")

mtbs$setAttributeFilter("incid_name = 'MAPLE'")
mtbs$getFeatureCount()  # 1

(feat <- mtbs$getNextFeature())

plot(feat, col = "red", border = NA, add = TRUE)

mtbs$close()
bnd$close()
bnd_mtsp$close()

gdalraster documentation built on June 8, 2025, 12:37 p.m.