# Google Earth Engine Data API Image

GDAL/OGR >= 2.4

The driver supports read-only operations to access image content, using Google Earth Engine REST API.

## Dataset name syntax

The minimal syntax to open a datasource is :

    EEDAI:[asset][:band_names]

where asset is something like projects/earthengine-public/assets/COPERNICUS/S2/20170430T190351_20170430T190351_T10SEG, and band_names a comma separated list of band names (typically indicated by subdatasets on the main image)

## Open options

The following open options are available :

- ASSET=string: To specify the asset if not specified in the connection string.
- BANDS=bandname1[,bandnameX]*: Comma separated list of band names.
- PIXEL_ENCODING=AUTO/PNG/JPEG/AUTO_JPEG_PNG/GEO_TIFF/NPY: Format in which to request pixels.
- BLOCK_SIZE=integer: Size of a GDAL block, which is the minimum unit to query pixels. Default is 256.

## Authentication methods

The following authentication methods can be used:

- Authentication Bearer header passed through the EEDA_BEARER or EEDA_BEARER_FILE configuration options.
- Service account private key file, through the GOOGLE_APPLICATION_CREDENTIALS configuration option.
- OAuth2 Service Account authentication through the EEDA_PRIVATE_KEY/ EEDA_PRIVATE_KEY_FILE + EEDA_CLIENT_EMAIL configuration options.
- Finally if none of the above method succeeds, the code will check if the current machine is a Google Compute Engine instance, and if so will use the permissions associated to it (using the default service account associated with the VM). To force a machine to be detected as a GCE instance (for example for code running in a container with no access to the boot logs), you can set CPL_MACHINE_IS_GCE to YES.

## Configuration options

The following configuration options are available :

- EEDA_BEARER=value: Authentication Bearer value to pass to the API. This option is only useful when the token is computed by external code. The bearer validity is typically one hour from the time where it as been requested.
- EEDA_BEARER_FILE=filename: Similar to EEDA_BEARER option, except than instead of passing the value directly, it is the filename where the value should be read.
- GOOGLE_APPLICATION_CREDENTIALS=file.json: Service account private key file that contains a private key and client email
- EEDA_PRIVATE_KEY=string: RSA private key encoded as a PKCS#8 PEM file, with its header and footer. Used together with EEDA_CLIENT_EMAIL to use OAuth2 Service Account authentication. Requires GDAL to be built against libcrypto++ or libssl.
- EEDA_PRIVATE_KEY_FILE=filename: Similar to EEDA_PRIVATE_KEY option, except than instead of passing the value directly, it is the filename where the key should be read.
- EEDA_CLIENT_EMAIL=string: email to be specified together with EEDA_PRIVATE_KEY/EEDA_PRIVATE_KEY_FILE to use OAuth2 Service Account authentication.

## Overviews

The driver expose overviews, following a logic of decreasing power of 2 factors, until both dimensions of the smallest overview are lower than 256 pixels.

## Subdatasets

When all bands don't have the same georeferencing, resolution, CRS or image dimensions, the driver will expose subdatasets. Each subdataset groups together bands of the same dimension, extent, resolution and CRS.

## Metadata

The driver will expose metadata reported in "properties" as dataset-level or band-level metadata.

## Pixel encoding

By default (PIXEL_ENCODING=AUTO), the driver will request pixels in a format compatible of the number and data types of the bands. The PNG, JPEG and AUTO_JPEG_PNG can only be used with bands of type Byte.

### Examples

- Get metadata on an image:

      gdalinfo "EEDAI:" -oo ASSET=projects/earthengine-public/assets/COPERNICUS/S2/20170430T190351_20170430T190351_T10SEG --config EEDA_CLIENT_EMAIL "my@email" --config EEDA_PRIVATE_KEY_FILE my.pem

  or

      gdalinfo "EEDAI:projects/earthengine-public/assets/COPERNICUS/S2/20170430T190351_20170430T190351_T10SEG" --config EEDA_CLIENT_EMAIL "my@email" --config EEDA_PRIVATE_KEY_FILE my.pem

  ## See Also:

  - Google Earth Engine Data API driver