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README.md

openeo-earthengine-driver

openEO back-end driver for Google Earth Engine.

This back-end currently supports openEO API version 0.3.1. Legacy versions are available as releases.

Demo

Multiple user accounts are available to be used (group1, group2, ... until group15), each with password test123.

Setting up an instance

The driver is written in node.js and requires at least version 11.0.0. Install node.js and npm according to the official documentation of each software package. Often node.js is shipped together with npm.

Afterwards either download the files in this repository or clone it. Run npm install to install the dependencies

Configuration

There are several important configuration options in the file config.json:

  • hostname: The address of the server running the openEO GEE driver. For local deployments usually 127.0.0.1, for public instances the ip or domain name of the server, e.g. earthengine.openeo.org.
  • port: The port the HTTP instance of the openEO GEE driver is running on.
  • ssl: Configuration to enable HTTPS (secured HTTP with SSL).
    • port: The port the HTTPS (secured) instance of the openEO GEE driver is running on.
    • key: If you want to create an HTTPS server, pass in a private key. Otherwise set to null.
    • certificate: If you want to create an HTTPS server, pass in a PEM-encoded certificate. Otherwise set to null.
  • serviceAccountCredentialsFile: See section 'Setting up GEE authentication'.

Setting up GEE authentication

The server needs to authenticate with a service accounts using a private key. The account need to have access rights for earth engine. You need to drop your private key file into a secure place specify the file path of the private key in the property serviceAccountCredentialsFile in the file config.json.

More information about authentication can be found in the Earth Engine documentation.

Starting up the server

After configuration, the server can be started. Run npm run start to start the server.

Usage

For both the demo servers or your own instance you can use the openEO API to communicate with Google Earth Engine.

An exemplary process graph to create an on-demand XYZ web-service looks like this:

{
  "process_id": "stretch_colors",
  "imagery": {
    "process_id": "min_time",
    "imagery": {
      "process_id": "NDVI",
      "imagery": {
        "process_id": "filter_daterange",
        "imagery": {
          "process_id": "get_collection",
          "name": "COPERNICUS/S2"
        },
        "extent": [
          "2018-01-01T00:00:00Z",
          "2018-01-31T23:59:59Z"
        ]
      },
      "red": "B4",
      "nir": "B8"
    }
  },
  "min": -1,
  "max": 1
}

This translates into the following Google Earth Engine Playground script:

// create image collection
var img = ee.ImageCollection('COPERNICUS/S2');

// filter_daterange
img = img.filterDate("2018-01-01T00:00:00Z", "2018-01-31T23:59:59Z");

// ndvi
img = img.map(function(image) {
  return image.normalizedDifference(['B4', 'B8']);
});

// min_time
img = img.reduce('min');

// stretch_color and mapping
Map.addLayer(img, {min: -1, max: 1, palette: ['black', 'white']});

Further documentation can be found in the docs/ directory, but is currently work in progress.

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