ee_as_stars: Convert an Earth Engine (EE) image in a stars object
In csaybar/rgee: R Bindings for Calling the 'Earth Engine' API

Description Usage Arguments Details Value See Also Examples

Convert an ee$Image in a stars object.

ee_as_stars(
  image,
  region = NULL,
  dsn = NULL,
  via = "drive",
  container = "rgee_backup",
  scale = NULL,
  maxPixels = 1e+09,
  lazy = FALSE,
  public = TRUE,
  add_metadata = TRUE,
  timePrefix = TRUE,
  quiet = FALSE,
  ...
)

`image`	ee$Image to be converted into a stars object.
`region`	EE Geometry (ee$Geometry$Polygon) which specify the region to export. CRS needs to be the same that the argument `image`, otherwise, it will be forced. If not specified, image bounds are taken.
`dsn`	Character. Output filename. If missing, a temporary file is created.
`via`	Character. Method to export the image. Two method are implemented: "drive", "gcs". See details.
`container`	Character. Name of the folder ('drive') or bucket ('gcs') to be exported into.
`scale`	Numeric. The resolution in meters per pixel. Defaults to the native resolution of the image.
`maxPixels`	Numeric. The maximum allowed number of pixels in the exported image. The task will fail if the exported region covers more pixels in the specified projection. Defaults to 100,000,000.
`lazy`	Logical. If TRUE, a `future::sequential` object is created to evaluate the task in the future. See details.
`public`	Logical. If TRUE, a public link to the image is created.
`add_metadata`	Add metadata to the stars_proxy object. See details.
`timePrefix`	Logical. Add current date and time (`Sys.time()`) as a prefix to files to export. This parameter helps to avoid exported files with the same name. By default TRUE.
`quiet`	Logical. Suppress info message
`...`	Extra exporting argument. See ee_image_to_drive and ee_image_to_gcs.

ee_as_stars supports the download of ee$Images by two different options: "drive" (Google Drive) and "gcs" ( Google Cloud Storage). In both cases ee_as_stars works as follow:

1. A task is started (i.e. ee$batch$Task$start()) to move the ee$Image from Earth Engine to the intermediate container specified in argument via.
2. If the argument lazy is TRUE, the task will not be monitored. This is useful to lunch several tasks at the same time and call them later using ee_utils_future_value or future::value. At the end of this step, the ee$Image is stored on the path specified in the argument dsn.
3. Finally if the argument add_metadata is TRUE, a list with the following elements is added to the stars-proxy object.
- if via is "drive":
  - ee_id: Name of the Earth Engine task.
  - drive_name: Name of the Image in Google Drive.
  - drive_id: Id of the Image in Google Drive.
  - drive_download_link: Download link to the image.
- if via is "gcs":
  - ee_id: Name of the Earth Engine task.
  - gcs_name: Name of the Image in Google Cloud Storage.
  - gcs_bucket: Name of the bucket.
  - gcs_fileFormat: Format of the image.
  - gcs_public_link: Download link to the image.
  - gcs_URI: gs:// link to the image.
Run attr(stars, "metadata") to get the list.

For getting more information about exporting data from Earth Engine, take a look at the Google Earth Engine Guide - Export data.

A stars-proxy object

Other image download functions: ee_as_raster(), ee_as_thumbnail(), ee_imagecollection_to_local()

## Not run: 
library(rgee)

ee_Initialize(drive = TRUE, gcs = TRUE)
ee_user_info()

# Define an image.
img <- ee$Image("LANDSAT/LC08/C01/T1_SR/LC08_038029_20180810")$
  select(c("B4", "B3", "B2"))$
  divide(10000)

# OPTIONAL display it using Map
Map$centerObject(eeObject = img)
Map$addLayer(eeObject = img, visParams = list(max = 0.4,gamma=0.1))

# Define an area of interest.
geometry <- ee$Geometry$Rectangle(
  coords = c(-110.8, 44.6, -110.6, 44.7),
  proj = "EPSG:4326",
  geodesic = FALSE
)

## drive - Method 01
# Simple
img_02 <- ee_as_stars(
  image = img,
  region = geometry,
  via = "drive"
)

# Lazy
img_02 <- ee_as_stars(
  image = img,
  region = geometry,
  via = "drive",
  lazy = TRUE
)

img_02_result <- img_02 %>% ee_utils_future_value()
attr(img_02_result, "metadata") # metadata

## gcs - Method 02
# Simple
img_03 <- ee_as_stars(
  image = img,
  region = geometry,
  container = "rgee_dev",
  via = "gcs"
)

# Lazy
img_03 <- ee_as_stars(
  image = img,
  region = geometry,
  container = "rgee_dev",
  lazy = TRUE,
  via = "gcs"
)

img_03_result <- img_03 %>% ee_utils_future_value()
attr(img_03_result, "metadata") # metadata

# OPTIONAL: clean containers
ee_clean_container(name = "rgee_backup", type = "drive")
ee_clean_container(name = "rgee_dev", type = "gcs")

## End(Not run)