Subset GRD with python

qiangwangcumt · September 20, 2019, 3:02pm

I would like to subset the GRD file with python based on lat/lon range. However, when i read the original tiff file with GDAL and there is no projection information. Anyone has any thoughts for how to get the lat/lon information from the original GRD file rather than using GIS software?

ABraun · September 20, 2019, 8:38pm

the tif file does not contain all the metadata required to process the raster properly.
You might have a look at the snappy libraries which use SNAP functionalities within Python.

instead of the tif file you import Sentinel-1 by the manifest.safe file.

github.com

senbox-org/snap-engine/blob/master/snap-python/src/main/resources/snappy/examples/snappy_subset.py

import sys

import snappy
from snappy import ProductIO, WKTReader

SubsetOp = snappy.jpy.get_type('org.esa.snap.core.gpf.common.SubsetOp')

if len(sys.argv) != 3:
    print("usage: %s <file> <geometry-wkt>" % sys.argv[0])
    print("       %s ./TEST.N1 \"POLYGON((15.786082 45.30223, 11.798364 46.118263, 10.878688 43.61961, 14.722727"
          "42.85818, 15.786082 45.30223))\"" % sys.argv[0])
    sys.exit(1)

file = sys.argv[1]
wkt = sys.argv[2]

geom = WKTReader().read(wkt)

print("Reading...")
product = ProductIO.readProduct(file)

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Full workflow (including subset): http://remote-sensing.eu/preprocessing-of-sentinel-1-sar-data-via-snappy-python-module/