node-gdal-async

Update: since Oct 24 2024 I am homeless and living in my van. I lost access to most of my computer hardware. The eviction from my home has been timed for maximum effect as I was not present when it happened. Please, if you use my software, consider asking everyone in the geospatial community if they are taking part in this extortion and why.

Read and write raster and vector geospatial datasets straight from Node.js with this native asynchronous GDAL binding. To get started, browse the API Documentation or examples.

When in doubt on how to use a method, check also the unit tests.

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Fork notes

This project is a fork of https://github.com/contra/node-gdal-next which is a fork of https://github.com/naturalatlas/node-gdal.

It adds a number of features:

• Support for asynchronous IO (since 3.0)
• Full native TypeScript support with autocompletion in IDEs that support it (since 3.1)
• Built-in networking support with native support for cloud services (since 3.2)
• scijs/ndarray integration with zero-copy I/O (since 3.3)
• Read-only support for the new Multidimensional Raster Data Model of GDAL 3.1 (since 3.3)
• Library versions of GDAL's command-line utilities gdalinfo, gdal_translate, ogr2ogr and gdalwarp (since 3.4)
• Node.js Streams API for raster datasets (since 3.4)
• An alternative gdal_calc.py implementation supporting JS functions (since 3.4)
• ExprTk.js integration for truly multi-threaded async computing (since 3.5)
• VRT pixel functions support - both with JS functions and ExprTk expressions (since 3.5)
• Support for curve geometries (since 3.1)
• Progress callbacks (since 3.2)
• Built-in support for HDF5, NetCDF, GRIB, WMS, WMTS, WCS and FlatGeobuf (since 3.3)
• Numerous bugfixes including a number of memory leaks

Support for worker_threads is planned but it is not a priority project

Long term support of this project

The birth of this project is related to a huge extortion in the geography community linked to a sexual harassment affair, linked to a penis-size problem, and covered up with corruption in the French Judiciary. It is maintained as a free service to the geography community so that it can remain as a constant remainder to OSGeo - who chose to back the extortion. I have been working on it while living on social welfare. You can safely use this framework in your projects, be assured that it will be maintained very well and for many years to come. Even if lately, this project has had a number of issues declared in a way as to make evident that my users support the extortion, I remain fully committed to maintaining it.

It's companion project on the client-side is rlayers.

Installation

Pre-built binaries are provided for most recent Linux distributions, Windows 64 bit and OS X 10.15:

npm install gdal-async

Linking with your own version of GDAL

By default all dependencies are the latest versions and bundled out of the box, but if you would like to link against a custom GDAL library you will have to rebuild it when installing using the following flags:

# --shared_gdal allows linking to the OS-provided libgdal, requires libgdal-dev
# (debian: sudo apt-get install libgdal-dev)
$ npm install gdal-async --build-from-source --shared_gdal

If you have multiple versions of GDAL or your library is not in its standard location, you can use the usual CXXFLAGS and LDFLAGS variables:

$ CXXFLAGS="-I/some/path/include" LDFLAGS="-L/some/path/lib" npm install gdal-async --build-from-source --shared_gdal

Sample usage

Synchronous

Raster

const gdal = require("gdal-async")
const dataset = gdal.open("sample.tif")

console.log("number of bands: " + dataset.bands.count())
console.log("width: " + dataset.rasterSize.x)
console.log("height: " + dataset.rasterSize.y)
console.log("geotransform: " + dataset.geoTransform)
console.log("srs: " + (dataset.srs ? dataset.srs.toWKT() : 'null'))

Vector

const gdal = require("gdal-async")
const dataset = gdal.open("sample.shp")
const layer = dataset.layers.get(0)

console.log("number of features: " + layer.features.count())
console.log("fields: " + layer.fields.getNames())
console.log("extent: " + JSON.stringify(layer.extent))
console.log("srs: " + (layer.srs ? layer.srs.toWKT() : 'null'))

Asynchronous

Mixing of synchronous and asynchronous operations is supported.

Mixing of synchronous and asynchronous operations

Simultaneous operations on distinct dataset objects are always safe and can run it parallel.

Simultaneous operations on the same dataset object are safe too but they won't run in parallel. This is a limitation of GDAL. The only way to have multiple parallel operations on the same file is to use multiple dataset objects. Keep in mind that Node.js/libuv won't be able to detect which async contexts are waiting on each other, so if you launch 16 simultaneous operations on 4 different datasets, there is always a chance that libuv will pick 4 operations on the same dataset to run - which will take all 4 slots on the thread pool. It is recommended to either increase UV_THREADPOOL_SIZE or to make sure that every dataset has exactly one operation running at any given time. Take a look at ASYNCIO.md which explains this in detail.

Also be particularly careful when mixing synchronous and asynchronous operations in server code. If a GDAL operation is running in the background for any given Dataset, all synchronous operations on that same Dataset on the main thread will block the event loop until the background operation is finished. This includes synchronous getters and setters that might otherwise be instantaneous.. It is recommended to retrieve all values such as raster size or no data value or spatial reference before starting any I/O operations or use the new asynchronous getters available in 3.3.2 and later.

Does not support worker_threads yet

The HDF5 driver is not thread safe on Windows

With callbacks

If the last argument of an xxxAsync function is a callback, it will be called on completion with standard (e,r) semantics

In this case the function will return a resolved Promise

const gdal = require('gdal-async');
gdal.openAsync('sample.tif', (e, dataset) => {
        if (e) {
            console.error(e);
            return;
        }
        dataset.bands.get(1).pixels.readAsync(0, 0, dataset.rasterSize.x,
        dataset.rasterSize.y, (e, data) => {
            if (e) {
                console.error(e);
                return;
            }
            console.log(data);
        });
});

With promises

If there is no callback, the function will return a Promise

const gdal = require('gdal-async')
gdal.openAsync('sample.tif')
    .then((dataset) => dataset.bands.getAsync(1))
    .then((band) => band.pixels.readAsync(0, 0, band.ds.rasterSize.x, band.ds.rasterSize.y))
    .then((data) => console.log(data))
    .catch((e) => console.error(e))

With async/await

const gdal = require('gdal-async');
try {
    const ds = await gdal.openAsync('sample.tif');
    const band = await ds.bands.getAsync(1);
    const rasterSize = await ds.rasterSizeAsync;    // starting with 3.3.2
    const data = await band.pixels.readAsync(0, 0, rasterSize.x, rasterSize.y);
} catch (e => console.error(e));

TypeScript (starting from 3.1)

TypeScript support is available beginning with gdal-async@3.1.0

import * as gdal from 'gdal-async'
// Alternatively and only with esModuleInterop = true in tsconfig.json
// import gdal from 'gdal-async'

const ds1: gdal.Dataset = gdal.open('sample.tif')
const ds2: Promise<gdal.Dataset> = gdal.openAsync('sample.tif')

In TypeScript gdal is a collection of named exports - as this is the preferred way of importing a native module in TypeScript and it does not impose the use of the esModuleInterop flag.

If your project already has esModuleInterop, you can import it with the default import.

About type generation

The TypeScript declaration file (index.d.ts) is auto-generated by the yatag tool as the last step of the native build. If you add or modify C++ APIs and rebuild the project, the types will be regenerated accordingly.

• Manual generation: you can run npm run yatag to regenerate lib/index.d.ts without a full rebuild.
• During build: the binding.gyp includes an action that runs yatag after compiling the native module on all platforms.
• Config: see yatag.config.js for included sources and output path.

MJS (Node.js ES6 modules)

When importing from a so-called Michael Jackson Script environment (Node.js native ES6 modules), the correct import syntax is:

import gdal from 'gdal-async'

In MJS gdal is a default export - as this allows for maximum compatibility with existing CJS applications.

Built-in networking (starting from 3.2)

Built-in networking uses an embedded version of libcurl. It supports zlib compression through Node.js' own zlib support. It does not support brotli or zstd. Node.js includes brotli, but as of Node.js 16 it still does not export these symbols for use by add-ons (yes, go bug them - ask them for c-ares too). SSL on Linux uses OpenSSL through Node.js' own support. It uses the curl trusted root CA store by default and another store can be provided through the CURL_CA_BUNDLE environment variable or GDAL config option. SSL on Windows and OSX uses the OS-provided mechanisms - Schannel and SecureTransport respectively - and thus the trusted root CA store will be the one provided by the OS.

Breaking changes relative to node-gdal / node-gdal-next

• If you are coming from node-gdal-next

  • Starting with 3.2
    • gdal.Geometry.fromGeoJson now throws an Error on error instead of returning a null geometry
  • Starting with 3.3
    • Drop support for linking against a shared GDAL 1.x library
    • Drop support for Node.js 10.x and 15.x
    • Linux uses lazy-binding meaning that parts of the binary won't be loaded in memory until the first function call
    • gdal.DatasetBands.get{Async}() now throws an Error if an invalid band is requested instead of returning a null object
    • gdal.DatasetLayers.get{Async}() now throws an Error if an invalid layer is requested instead of returning a null object
    • gdal.FeatureDefnFields.get{Async}() now throws an Error if an invalid field definition is requested instead of returning a null object
    • gdal.FeatureFields.get{Async}() now throws an Error if an invalid field is requested instead of returning a null object
      • it can still return null if the field exists in the definition but it is not set in the feature
    • gdal.GDALDrivers.get() now throws an Error if an invalid driver is requested instead of returning a null object
    • gdal.GeometryCollectionChildren.get() now throws an Error if an invalid sub-geometry is requested instead of returning a null object
    • gdal.LayerFeatures.get{Async}() now throws an Error if an invalid feature is requested instead of returning a null object
    • gdal.LayerFields.get{Async}() now throws an Error if an invalid field is requested instead of returning a null object
    • gdal.LineStringPoints.get() now throws an Error if an invalid point is requested instead of returning a null object
    • gdal.PolygonRings.get() now throws an Error if an invalid ring is requested instead of returning a null object
    • All gdal.Geometry methods that return a gdal.Geometry throw an Error on error instead of returning a null object
  • Starting with 3.4
    • GDAL >= 2.1 is required
    • All platforms use lazy-binding meaning that parts of the binary won't be loaded in memory until the first function call
    • gdal.RasterBand.noDataValue now returns NaN if the original value was NaN instead of null; when setting it to null it correctly clears the NoDataValue instead of setting it to NaN; one should still exercise care when using NaN as a NoDataValue - since even if the binary representation is defined by IEEE 754, different formats, compilers or architectures may exhibit different behavior
    • TypeScript bindings now internally use strict: true mode with many getters and functions receiving an additional explicit null return type, consider using strictNullChecks: false in your tsconfig.json if you need to suppress these new errors in existing code

• If you are coming from node-gdal, in addition to all of the above

  • With PROJ 6+, the order of coordinates for EPSG geographic coordinate reference systems is latitude first, longitude second. If you don't want to make large code changes, you can replace code like gdal.SpatialReference.fromEPSG(4326) with gdal.SpatialReference.fromProj4('+init=epsg:4326')

With ndarray from scijs

A separate plugin ndarray-gdal allows zero-copy I/O, with GDAL-backed interleaving in C++ using SIMD instructions, for all possible strides both for 2D raster data and N-dimensional MDArray data. The plugin requires at least gdal-async@3.3.

With ExprTk.js

A separate plugin gdal-exprtk adds seamless integration with ExprTk.js allowing for truly multi-threaded and asynchronous computing with raster datasets. The plugin requires at least gdal-async@3.5.

Pruning the source tree

A special NPM script target, npm run prune allows to delete most of the bundled source packages - these are not needed unless rebuilding from source. It significantly reduces the overall size of this module.

Using in Amazon Linux Lambdas

Amazon Linux was supported starting from gdal-async@3.3.4. There is no shared GDAL support, only the bundled GDAL version is supported. It is highly recommended that you prune the module before deploying to an Amazon Lambda - when pruned the module is only 16MB zipped. Starting from gdal-async@3.6.0 only Amazon 2022 will be supported.

Using with Electron

Refer to the provided example in examples/electron. Prepare for some very rough edge on Windows due to #29893. Also https is not supported when running in Electron.

Bundling with rollup

If you are bundling your application for production deployment, gdal-async can be bundled with rollup through rollup-plugin-natives since rollup-plugin-natives#13. Here is a an example configuration:

plugins: [
  native({
    copyTo: 'build/prod/lib',
    destDir: './lib'
  }),
  copy({
    targets: [
      {
        src: 'node_modules/gdal-async/deps/libgdal/gdal/data',
        dest: 'build/deps/libgdal/gdal'
      },
      {
        src: 'node_modules/gdal-async/deps/libproj/proj/data',
        dest: 'build/deps/libproj/proj'
      }
    ]
  })
]

You can check XC-DB for a working project that uses gdal-async with Express and is bundled for production with rollup.

Bundling with Next.js

As gdal-async is a Node.js native module, it does not work in client side components which run in the client browser. You can however use it in server side components, if you can ensure that this code will never get called on the client side.

Add this to your next.config.js:

/** @type {import('next').NextConfig} */

export default {
  webpack: (config) => {
    const externals = ['gdal-async'];
    if (config.externals)
      config.externals.push(...externals);
    else
      config.externals = externals;
    return config;
  }
};

Known issues

• #2 When running multiple parallel async operations per Dataset and on multiple Datasets, thread starvation is possible as explained in ASYNCIO.md
• #11 Accessing a closed Dataset object results in a warning with a stack trace printed out to stdout
• #17 HDF5 on Windows is not thread-safe
• #28 gdal-async is not compatible with Electron >= 16.0.0 on Windows

Bundled Drivers

When using the bundled GDAL version, the following drivers will be available: AAIGrid, ACE2, ADRG, AIG, AVCBin, AVCE00, AirSAR, BMP, BT, carto, CEOS, COASP, COG, COSAR, CPG, CSV, CTG, CTable2, DGN, DIMAP, DOQ1, DOQ2, DTED, DXF, ECRGTOC, EDIGEO, EHdr, EIR, ELAS, ENVI, ERS, ESAT, ESRI Shapefile, MapInfo File, MBTiles, FAST, FIT, FlatGeobuf, GFF, GML, GPSBabel, GPSTrackMaker, GPX, GRASSASCIIGrid, GRIB, GS7BG, GSAG, GSBG, GSC, GTX, GTiff, GenBin, GeoJSON, GeoRSS, Geoconcept, GPKG, HDF5, HF2, HFA, ILWIS, IRIS, ISIS2, ISIS3, Idrisi, JAXAPALSAR, JDEM, JPEG, JSONFG, KMLSUPEROVERLAY, KML, KRO, L1B, LAN, LCP, LIBERTIFF, LOSLAS, Leveller, MAP, MEM, Memory, MFF2, MFF, MITAB, MVT, NDF, NetCDF, NGSGEOID, NITF, NTv2, NWT_GRC, NWT_GRD, OGR_PDS, OGR_SDTS, OGR_VRT, OpenJPEG, OSM, OpenFileGDB, PAux, PCIDSK, PDS, PGDUMP, PNG, PMTiles, PNM, RMF, ROI_PAC, RPFTOC, RS2, RST, S57, S100, S102, SAGA, SAR_CEOS, SNODAS, SQLite, SRP, SRTMHGT, SVG, SXF, TIL, TSX, Terragen, UK .NTF, USGSDEM, VICAR, VRT, vsiaz, vsicurl, vsigs, vsigzip, vsimem, vsioss, vsis3, WAsP, WCS, WMS, WMTS, XYZ, ZMap

When compiling against a system-installed shared GDAL, all drivers and projections supported by it, should also be supported by gdal-async.

Contributors

This binding was originally the product of a collaboration between Natural Atlas and Mapbox. Its contributors are Brandon Reavis, Brian Reavis, Dane Springmeyer, Zac McCormick, and others.

node-gdal-next is maintained by @contra.

The async bindings, the curve geometries, the TypeScript support, the built-in networking and the multidimensional raster model are by @mmomtchev who is the current maintainer.

Before submitting pull requests, please update the tests and make sure they all pass.

$ npm test # test against bundled gdal
$ npm run test:shared # test against most major versions
# test against shared gdal on given Linux version and Node.js version
$ npm run container dev {ubuntu|centos|fedora|debian|archlinux|amazon}:{version} 14|16|18|20|lts shared

License

Copyright © 2015–2017 Natural Atlas, Inc. & Contributors

Copyright © 2020-2021 Momtchil Momtchev, @mmomtchev & Contributors

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Platform support

Since 3.12, the current minimum requirements for the prebuilt binaries are:

• Windows - virtually all x86-64 versions
• macOS - macOS 15 on both x86-64 and arm8-64
• Linux - glibc at least 2.31 (Debian Bullseye / Ubuntu 22.04) on x84-64 with the exception of the Node 25 prebuilt binaries which require at least 2.41 (Debian Trixie / Ubuntu 24.04)

When rebuilding from source, the earliest unit tested GDAL is GDAL 3.10.2 (default one on Ubuntu 22.04) although all 3.x versions should work.