[SOLVED] Converting pixel position to geographical coordinates (lat, long) for a Sentinel-1 SAR image

Converting pixel position to geographical coordinates (lat, long) for a Sentinel-1 SAR image

How can i get the geographical coordinates from x,y position in a Sentinel-1 Synthetic Aperture Radar (SAR) satellite image?

For example, I can access a downloaded image info sg as

from snappy import ProductIO
from snappy import PixelPos 
path='path_name'
product = ProductIO.readProduct(path)
sg = product.getSceneGeoCoding()

But how can I get latitude and longitude for a desired point (x, y) in sg using ESA's snap engine within Python?

Solution

Using the custom function below, we can easily convert any point inside our image sg to its coordinates (latitude,longitude):

def LatLon_from_XY(ProductSceneGeoCoding, x, y):
    #From x,y position in satellite image (SAR), get the Latitude and Longitude
    geopos = ProductSceneGeoCoding.getGeoPos(PixelPos(x, y), None)
    latitude = geopos.getLat()
    longitude = geopos.getLon()
    return latitude, longitude

UPD: Because of various snap version updates, function above may not be working properly. Function below should work most of the times.

def LatLon_from_XY(product, x, y):
    geoPosType = jpy.get_type('org.esa.snap.core.datamodel.GeoPos')
    geocoding = product.getSceneGeoCoding()
    geo_pos = geocoding.getGeoPos(snappy.PixelPos(x, y), geoPosType())
    if str(geo_pos.lat)=='nan':
        raise ValueError('x, y pixel coordinates not in this product')
    else:
        return geo_pos.lat, geo_pos.lon

E.g. for the given sg product, we can get coordinates of pixel (x=12000, y=2000) as

latitude, longitude = LatLon_from_XY(sg, 12000, 2000)