geotiff.js

geotiff.js provides limited support for the BigTIFF format due to JavaScript's handling of 64-bit integers. Users should be aware of the following behaviors:

• Precision: 64-bit integers are read as two 32-bit integers and combined. Because JavaScript numbers are typically 64-bit floats, inaccuracies may occur for extremely large values.
• Data Types: For 64-bit integer arrays, the library uses the default Array type. This may cause issues with certain compression algorithms if these arrays are used for pixel values.

When working with GeoTIFF objects (rather than GeoTIFFImage objects), you can call readRasters() directly on the tiff object. This enables automatic selection of the best image based on your requirements:

• Resolution-based: If you provide width, height, resX, or resY, the library selects the best-fitting image (e.g., an overview).
• Geographic-based: If you provide a bbox instead of a window, the library uses geographic coordinates to select the appropriate image/overview.

// Uses geographic bbox and selects best fitting overview based on resolution
const data = await tiff.readRasters({
  bbox: [10.34, 57.28, 13.34, 60.23],
  resX: 0.1,
  resY: 0.1
});

GeoTIFF.js can be used in Node.js environments via require or import, or directly in the browser using a <script> tag. The library exposes factory functions like fromUrl, fromUrls, fromArrayBuffer, and fromBlob to create GeoTIFF objects.

// Node.js CommonJS
const GeoTIFF = require('geotiff');
const { fromUrl, fromUrls, fromArrayBuffer, fromBlob } = GeoTIFF;

// ES Modules
import GeoTIFF, { fromUrl, fromUrls, fromArrayBuffer, fromBlob } from 'geotiff';

// Browser CDN
// <script src="https://cdn.jsdelivr.net/npm/geotiff"></script>
// console.log(GeoTIFF);

To build the library from source, run the build command. This generates two separate builds: one for the browser and one for Node.js.

Output locations:

• Browser: dist-browser/main.js
• Node.js: dist-node/main.js

npm run build

You can install the geotiff package using npm to include it in your project dependencies.

npm install geotiff

For quick integration without a package manager, you can use the prebuilt version via a CDN by adding a script tag to your HTML.

<script src="https://cdn.jsdelivr.net/npm/geotiff"></script>

To run the library's test suite, you must first set up the test data. This requires GDAL and ImageMagick to be installed on your system.

1. Install Dependencies

Ubuntu (using ubuntugis-unstable):

sudo add-apt-repository -y ppa:ubuntugis/ubuntugis-unstable
sudo apt-get update
sudo apt-get install -y gdal-bin imagemagick

MacOS (using Homebrew):

brew install wget gdal imagemagick

2. Setup Test Data

Once the tools are installed, run the setup script located in the test/data directory:

cd test/data
sh setup_data.sh
cd -

3. Execute Tests

Run the test suite using npm:

npm test

To run tests directly in a browser environment, start the development server and navigate to the provided local URL.

```bash
npm run dev

After running the command, navigate to http://localhost:8090/test/ in your browser.

To set up the repository for development, clone the repository and install the dependencies using npm.

# clone repo
git clone https://github.com/constantinius/geotiff.js.git
cd geotiff.js/

# install development dependencies
npm install