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Published October 29, 2019 | Version 1.1
Dataset Open

CNES ALCD Open water masks

  • 1. CNES

Contributors

Producer:

  • 1. C-S

Description

"CNES ALCD Open water masks" is a reference dataset for water masks based on Sentinel-2 (L1C) images.

This dataset generation has been funded by CNES under the SWOT-Downstream programme.

Generation Method

This dataset has been generated with the Active Learning for Cloud Detection (ALCD) software developed by CNES/Cesbio, that enables to generate any kind of reference mask using satellite images.

This procedure involves between 1 or 2 hours of work to generate each reference image : create reference points on the image (water, land, cloud, snow...) manually, do the training (based on Random Forest of OTB) and prediction with ALCD, add new reference points for the most problematic areas, repeat new training/predictions as many times as necessary (usually 3-5 iterations), and finally, do a manual correction of persistent errors.

Dataset format (raw masks)

The dataset contains 16 files (scenes) at 10m resolution for 110km x 110km size.

The content of pixels of the scene files (geotiff) follows the following naming rule
     0 = Non Water observation (as land, snow)
     1 = Open Water observation
     255 = no data (as clouds)

Format of file names:

       T{tile}_{YYYMMDD}_{site}_{season}.tif

       where : tile = reference Sentinel 2 tile (Cesbio post), YYYYMMDD = date of Sentinel 2 acquisition, site = name of the site, season = summer, winter

Example :  T30TXQ_20180201_Bordeaux_winter.tif

             T30UXU_20180708_Bretagne_summer.tif


Dataset format (inland masks)

This dataset has a version without coastal/ocean waters called "inland masks" aimed to characterize just inland waters.

The dataset has been processed with the coastal lines of GSSHG layers : https://www.soest.hawaii.edu/pwessel/gshhg/ in H level, and using an erosion of 400m towards the continent.
Thus, any pixel closer to the GSSHG coast line than 400m and beyond will be considered as "no data"(value=255).

The format of the pixels content and file naming follow the same rules as in the "raw masks" version.

 

Files

CNES_ALCD_Open_water_masks_v1.1.zip

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