DownloadSentinel2: Download Sentinel 2 dataset from google cloud.
In mcgregorian1/sealR: A number of helpful functions for SEAL at NCSU

Description Usage Arguments Details Examples

View source: R/DownloadSentinel2.R

This function downloads all Sentinel 2 images (L1C or L2A) from Google's repository. These images are the same as if you downloaded these from ESA Copernicus, but faster (i.e. you don't have to request images and wait for them). Note that Google does not do their own L2A conversion - all L2A images are supplied directly from Copernicus (true as of April 2021).

1	DownloadSentinel2(tilename, folder, L2Flag = FALSE, regExp = NULL)

`tilename`	what tile do you want to download
`folder`	local folder used to store downloaded files
`L2Flag`	indicate to download L2A product or L1C product (default)
`regExp`	regular expression, with which you can speicify which files you want. For example, regExp <- "S2\D_MSIL\d\D_201([6]\|[8][0][0-9]).*.SAFE/$" means you want data from 2016 and before 2018 before October.

Running this function requires Google Cloud Storage SDK, which you can download and install from https://cloud.google.com/sdk/docs/install. For your first time attempting to run the function you will need to open a python script and run 'gcloud auth login', which will take you to log in to your google account.

NOTE this function can NOT be run in RStudio because RStudio does not recognize 'gsutil'. You need to use a different code editor, whether that's R terminal or VSCode.

If you need help figuring out whether your regex is correct, see http://www.goring.org/resources/tutorial.html. Note if you do use something like regex101.com that in R, a double slash = a single slash, even though this isn't true for other languages.

If you want to figure out which tiles you need, check out this site for polygon shapefiles of the S2 tiles: https://github.com/justinelliotmeyers/Sentinel-2-Shapefile-Index. Using this you can easily filter to the ones you need using 'raster::intersect()' or something.

Once the function has started, press ctrl+c in the command line can stop it.

If there's any bug, please let me know.

Author: Jacory (Xiaojie Gao), description updated by Ian McGregor

DownloadSentinel2("17SNA", "D:/", L2Flag = TRUE, rexExp = "S2\\D_MSIL\\d\\D_201([6]|[8][0][0-9]).*.SAFE/$")

# What if I want all L1C images from 2015 through to 2020-01-31? It will look like this:
DownloadSentinel2("17SNA", "D:/",  L2Flag = FALSE, regExp = "S2\\D_MSIL\\d\\D_20([1][5-9]|[2][0][0][1]).*.SAFE/$")