How to make a mosaic of Theia snow products in three command lines

Simon Gascoin, 11 décembre 2020

Assuming that you have downloaded from Theia and unzipped several products in the same directory. Assuming that you have a Linux OS with GNU Parallel, GDAL and OTB command line utilities installed..

Then, in your terminal, type:

# Get the color table
wget https://gitlab.orfeo-toolbox.org/remote_modules/let-it-snow/-/raw/75-lis-color-table-for-otb-not-updated-after-changed-nodata/hpc/LIS_SEB_style_OTB.txt
# reproject all SNW raster products to a common system (here Web Mercator) and assign 255 to nodata
parallel gdalwarp -srcnodata 255 -overwrite -r near -t_srs "EPSG:3857" {} {/} ::: $(ls SEN*/*SNW*.tif)
# Apply color table
parallel otbcli_ColorMapping -in {} -out c{} uint8 -method.custom.lut LIS_SEB_style_OTB.txt ::: $(ls S*SNW*.tif)
# Merge colored images and set 0 to nodata
gdal_merge.py -n 0 c*tif -o mosaic.tif -co COMPRESS=DEFLATE

This is yesterday’s snow cover map of the entire French Alps (10 December 2020). Snow is cyan, clouds are white.

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