User:AkuAnakTimur/Sentinel-2 imagery in JOSM

From OpenStreetMap Wiki
Jump to navigation Jump to search
Comparison between imageries: Bing, ASTER, Sentinel-2 and Landsat 8.

This is how I exploit Sentinel-2 imagery to be used as a tracing layer directly in the JOSM editor.

  1. JOSM should have the ImportImagePlugin installed.
  2. Install a copy of QGIS on your machine.
  3. Register for a free account on the Copernicus Open Access Hub. See this guide.
  4. With an account from Copernicus Open Access Hub, it's time to download a copy of the data (between 200MB and nearly 1GB zip files)! Personally I use Sentinel-hub EO Browser to get it. Use credentials from Copernicus Open Access Hub to proceed downloading them.
  5. In the downloaded zip file, browse for the /GRANULE/a folder with a really long name/IMG_DATA/ subfolder. Use your favourite file manager. For this example, the folder with a really long name is L1C_T47NQD_A015059_20200124T034212.
  6. Look for a JP2000 file with a _TCI suffix for its name. See example in gallery below (the desired file is T47NQD_20200124T033029_TCI.jp2).
  7. Extract the file if it's still unzipped.
  8. Open the long filename_TCI file with QGIS. Adjust colour levels, trim if needed, etc. Save as TIFF file.
  9. View the TIFF file directly from JOSM! Trace, trace, trace to your heart!

Something else...

  • In addition to Sentinel-hub EO Browser, do check out Remote Pixel's Satellite Search. It's an alternative to pick your desired scene (er, in another word, available data where the satellite happened to blaze straight past your place). On top of that, you may enjoy scenes from Landsat 8 as well, if the recent ones from Sentinel-2 didn't meet your expectation. Downloading them, however, you must have access to AWS S3 Buckets (blah blah blah). However, the Landsat scenes are available for direct download, but later one must form a composite out of three (or four) files to make it useful for tracing.
  • Speaking of AWS S3 Bucket, if you have access to it, (Requester Pays, said AWS) you can easily download a single TCI (oh, which means True Colour Imagery) file, rather than downloading an archive which is 5-10 times bigger.
  • Why trimming (or extracting, per QGIS) is important? Unless your machine and Java/OpenJDK runtimes was set with higher memory consumption, weaker machines may struggle with even a 200MB-ish TIFF file.

Step-by-step in pictures

A bit of history

Why? Before more resources were shared by Esri and Maxar, and when Bing took a while to refresh their imagery, (keep in mind that this was 2013-2016), the available imagery for most of the country used to look much like the left part of this image:

Landsat7-Sentinel2.png

In the absence of any open data from my country, I considered imageries from Sentinel-2 (right part of the image) came to the rescue!

Well, they are still useful today, due to the frequent updates - considering that Microsoft, Maxar and Esri (probably more to come?) may not offer more frequent imagery refresh.