ogr2ogr

ogr2ogr enables file conversion and re-projection of spatial data through the use of ogr2ogr (gdal) tool

Requirements

ogr2ogr requires the command line tool ogr2ogr - gdal install page. We recommended using the latest stable version.

Installation

npm install ogr2ogr

Usage

ogr2ogr takes either a path, a stream, or a GeoJSON object. The result of the transformation can be consumed via callback or stream:

var ogr2ogr = require('ogr2ogr')
var ogr = ogr2ogr('/path/to/spatial/file')

ogr.exec(function (er, data) {
  if (er) console.error(er)
  console.log(data)
})

var ogr2 = ogr2ogr('/path/to/another/spatial/file')
ogr2.stream().pipe(writeStream)

or awaited as a promise

var data = await ogr2ogr('/path/to/another/spatial/file').promise()
console.log(data)

See /examples for usage examples and /test/api.js.

Configuring the base ogr2ogr command

An alternative to installing GDAL, you can invoke ogr2ogr via a GDAL Docker image instead. Do this by configuring the base command that is executed to invoke the ogr2ogr CLI.

var ogr2ogr = require('ogr2ogr')

ogr2ogr('/home/.../path/to/spatial/file')
  .command(
    'docker run -v /home/:/home --rm osgeo/gdal:alpine-small-latest ogr2ogr'
  )
  .exec(function (er, data) {
    if (er) console.error(er)
    console.log(data)
  })

Formats

The goal is for ogr2ogr to support most (if not all) formats your underlying ogr2ogr supports. You can see the progress of that in /tests/drivers.js.

It also will:

1. Extract zip files for formats that are typically bundled (i.e. shapefiles, kmz, s57, vrt, etc)
2. Will extract geometry from CSVs when a common geometry field can be determined.
3. Cleans up after its messes.
4. Bundles multi-file conversions as a zip
5. Support GeoJSON and GeoRSS urls as path inputs
6. Support raw GeoJSON objects as input

Options

ogr2ogr takes chainable modifier functions:

var shapefile = ogr2ogr('/path/to/spatial/file.geojson')
  .format('ESRI Shapefile')
  .skipfailures()
  .stream()
shapefile.pipe(fs.createWriteStream('/shapefile.zip'))

Available options include:

• .project(dest, src) - reproject data (defaults to: "ESPG:4326")
• .format(fmt) - set output format (defaults to: "GeoJSON")
• .timeout(ms) - milliseconds before ogr2ogr is killed (defaults to: 15000)
• .skipfailures() - skip failures (continue after failure, skipping failed feature -- by default failures are not skipped)
• .env(obj) - object of custom ogr2ogr ENV configuration parameters (e.g. { ATTRIBUTES_SKIP: 'YES' })
• .options(arr) - array of custom ogr2ogr arguments (e.g. ['-fieldmap', '2,-1,4'])
• .destination(str) - ogr2ogr destination (directly tell ogr2ogr where the output should go, useful for writing to databases)
• .onStderr(callback) - execute a callback function whose parameter is the debug output of ogr2ogr to stderr

Example of onStderr usage

If you want to debug what is the ogr2ogr binary doing internally, you can attach a callback to the output, provided you have passed the option CPL_DEBUG

var shapefile = ogr2ogr('/path/to/spatial/file.geojson')
  .format('ESRI Shapefile')
  .skipfailures()
  .options(['--config', 'CPL_DEBUG', 'ON'])
  .onStderr(function (data) {
    console.log(data)
  })
  .stream()
shapefile.pipe(fs.createWriteStream('/shapefile.zip'))

You will see in the console someting in the likes of

GDAL: GDALOpen(/tmp/ogr_542cb61092c/sample.shp, this=0x15ca370) succeeds as ESRI Shapefile.

GDAL: GDALDriver::Create(PGDUMP,/vsistdout/,0,0,0,Unknown,(nil))
PGDump: LaunderName('ID') -> 'id'
PGDump: LaunderName('FIPSSTCO') -> 'fipsstco'
PGDump: LaunderName('STATE') -> 'state'
PGDump: LaunderName('COUNTY') -> 'county'
GDALVectorTranslate: 1 features written in layer 'sample'
Shape: 1 features read on layer 'sample'.
GDAL: GDALClose(/tmp/ogr_542cb61092c/sample.shp, this=0x15ca370)
GDAL: GDALClose(/vsistdout/, this=0x157ded0)

This can be useful when something goes wrong and the error provided by this library doesn't provide enough information.

Conversion of shp files

It is trivial to handle the conversion of ESRI Shapefiles when they are packed in a zipfile that contains (at least) the shp and shx files. This library is also capable of converting uncompresses ESRI Shapefiles if you use the shp file as the input file and the shx file is in the same folder.

However, it is also possible to convert single shp files that lack an shx file by forcing its creation using ogr2ogr option SHAPE_RESTORE_SHX provided you have installed GDAL/OGR version 2.1.0 or newer.

var geojson = ogr2ogr('/path/to/spatial/lonely.shp')
  .options(['--config', 'SHAPE_RESTORE_SHX', 'TRUE'])
  .stream()

geojson.pipe(fs.createWriteStream('/lonely.json'))

Caveat: ogr2ogr will do its best to infer the corresponding shx. However, there's no guarantee it will success.

License

(The MIT License)

Copyright (c) 2021 Marc Harter [e-mail]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.