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I have a Sentinel 2A scene (downloaded from Sentinel AWS storage in UTM projection) and coordinates (a polygon of lat/lng) of a specific plot of land. How can I extract a piece corresponding to that field (preferably in EPSG 3857, so that I could overlay it on Google Maps) a piece corresponding to my plot of interest (or to a given Google Maps tile), using either Python or CLI tools?

I have used gdalwarp to transform the scene image to EPSG:3857, but how can I then transform the lat/lng coordinates of my plot's borders (or the given tile's borders) to the coordinates of the pixels I need to crop? Are there any ready-made utilities or libraries for that?

  • What format is your "polygon of lat/lng" in? Do you simply have a set of coordinates, or do you have a shp / kml / kmz? – Mikkel Lydholm Rasmussen Jun 6 '17 at 11:42
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If you have a rectangle bounding box you want to cut, you can use gdalwarp function with target extents (-te) and target extent srs (-te_srs) :

-te xmin ymin xmax ymax: set georeferenced extents of output file to be created (in target SRS by default, or in the SRS specified with -te_srs)

-te_srs srs_def: (GDAL >= 2.0) Specifies the SRS in which to interpret the coordinates given with -te. The srs_def may be any of the usual GDAL/OGR forms, complete WKT, PROJ.4, EPSG:n or a file containing the WKT. This must not be confused with -t_srs which is the target SRS of the output dataset. -te_srs is a convenience e.g. when knowing the output coordinates in a geodetic long/lat SRS, but still wanting a result in a projected coordinate system.

For example:

gdalwarp -te 10 40 15 45 -te_srs EPSG:4326 -t_srs EPSG:3857 infile outfile

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