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s1_orbit_func.py
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s1_orbit_func.py
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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed Oct 25 11:45:24 2017
@author: elindsey
"""
import os,sys,glob,datetime,requests,cgi
from xml.etree import ElementTree
def parse_s1_SAFE_name(safe_name):
"""
SAFE file has name like S1A_IW_SLC__1SDV_20150224T114043_20150224T114111_004764_005E86_AD02.SAFE (or .zip)
Function returns a list of 2 strings, 2 datetime objects and one integer ['A', 'IW_SLC', '20150224T114043','20150224T114111', 004764]
"""
#make sure we have just the file name
safe_name = os.path.basename(safe_name)
#extract string components and convert to datetime objects
sat_ab = safe_name[2]
sat_mode = safe_name[4:10]
date1 = datetime.datetime.strptime(safe_name[17:32],'%Y%m%dT%H%M%S')
date2 = datetime.datetime.strptime(safe_name[33:48],'%Y%m%dT%H%M%S')
orbit_num= int(safe_name[49:55])
return [sat_ab, sat_mode, date1, date2, orbit_num]
def get_latest_orbit_file(sat_ab,imagestart,imageend,s1_orbit_dirs,download_missing=True,skip_notfound=True,preciseonly=False,print_results=False):
"""
Orbit files have 3 dates: production date, start and end range. Image files have 2 dates: start, end.
We want to find the latest file (most recent production) whose range includes the range of the image.
If none is found, look for the file from ESA by default.
Return string includes absolute path to file.
"""
eoflist=[]
eofprodlist=[]
latest_eof=None
# add a half hour to the image start/end times to ensure we have enough coverage in the orbit file
imagestart_pad = imagestart - datetime.timedelta(hours=0.5)
imageend_pad = imageend + datetime.timedelta(hours=0.5)
# first, we check if this file has already been downloaded - look in the provided folders
# loop over multiple orbit folders, if provided
for s1_orbit_dir in s1_orbit_dirs:
# loop over orbit files in this folder
for item in glob.glob(s1_orbit_dir+"/S1"+sat_ab+"*.EOF"):
#get basename, and read dates from string
eof=os.path.basename(item)
[eofprod,eofstart,eofend] = get_dates_from_eof(eof)
#check if the EOF validity dates span the entire image
if eofstart < imagestart_pad and eofend > imageend_pad:
# exclude case where preciseonly is set and image is RESORB type
if not (preciseonly and 'AUX_RESORB' in eof):
eoflist.append(os.path.abspath(os.path.join(s1_orbit_dir,eof)))
#record the production time to ensure we get the most recent one
eofprodlist.append(eofprod)
#print the most recent valid EOF found in the folders
if eoflist:
found_existing=True
latest_eof = eoflist[eofprodlist.index(max(eofprodlist))]
# if no file was found locally, download from ESA if this is requested
elif download_missing:
found_existing=False
tstart=imagestart_pad.strftime('%Y-%m-%dT%H:%M:%S')
tend=imageend_pad.strftime('%Y-%m-%dT%H:%M:%S')
orbit = get_latest_orbit_copernicus_api(sat_ab,tstart,tend,'AUX_POEORB')
if not orbit and not preciseonly:
orbit = get_latest_orbit_copernicus_api(sat_ab,tstart,tend,'AUX_RESORB')
if orbit:
# set download location to one of the user-supplied folders. We assume the user would either supply one folder, or two folders with 'resorb' coming second.
if len(s1_orbit_dirs)>1 and orbit['orbit_type'] == 'AUX_RESORB':
target_dir=s1_orbit_dirs[1]
else:
target_dir=s1_orbit_dirs[0]
# download and return the full path to the file
latest_eof = download_copernicus_orbit_file(target_dir,orbit['remote_url'])
# nothing was found - print a warning or error
if not latest_eof or not os.path.exists(latest_eof):
if skip_notfound:
print("Warning: No matching orbit file found for Sentinel-1%s during time %s to %s in %s - skipping"%(sat_ab,imagestart_pad,imageend_pad,s1_orbit_dirs))
return None,False
else:
print("Error: No matching orbit file found for Sentinel-1%s during time %s to %s in %s"%(sat_ab,imagestart_pad,imageend_pad,s1_orbit_dirs))
sys.exit(1)
# print out a message about the result
if print_results and latest_eof is not None:
if found_existing:
print(f'Found existing file: {latest_eof}')
else:
print(f'Downloaded new file: {latest_eof}')
return latest_eof,found_existing
def download_latest_orbit(granule,target_dir,preciseonly):
# parse the SAFE filename to get sat_ab and start/end dates
[sat_ab, sat_mode, date1, date2, orbit_num] = parse_s1_SAFE_name(granule)
#pad times by 30 min
imagestart_pad = date1 - datetime.timedelta(hours=0.5)
imageend_pad = date2 + datetime.timedelta(hours=0.5)
# put padded times in API format
tstart=imagestart_pad.strftime('%Y-%m-%dT%H:%M:%S')
tend=imageend_pad.strftime('%Y-%m-%dT%H:%M:%S')
# try to download the precise orbit first
orbit = get_latest_orbit_copernicus_api(sat_ab,tstart,tend,'AUX_POEORB')
# try the restituted orbit if the precise failed
if not orbit:
if preciseonly:
print("Error: option --precise was set, but no precise orbit file found. Not trying restituted orbit search")
sys.exit(1)
else:
orbit = get_latest_orbit_copernicus_api(sat_ab,tstart,tend,'AUX_RESORB')
# download the orbit file
eof_filename = download_copernicus_orbit_file(target_dir, orbit['remote_url'])
return eof_filename
def get_latest_orbit_copernicus_api(sat_ab,start_time,end_time,orbit_type):
"""
Use the Copernicus GNSS products API to find the latest orbit file.
Input example formats: 'A', '2018-08-10T22:47:19', '2018-08-10T22:48:16', 'AUX_POEORB'
Returns a python dictionary, with elements 'orbit_type' (matching the input orbit_type) and 'remote_url'.
"""
# modified by E. Lindsey, April 2021
# some hard-coded URLs to make the API work
scihub_url='https://scihub.copernicus.eu/gnss/odata/v1/Products'
# these are from the namespaces of the XML file returned in the query. Hopefully not subject to change?
w3_url='{http://www.w3.org/2005/Atom}'
m_url='{http://schemas.microsoft.com/ado/2007/08/dataservices/metadata}'
d_url='{http://schemas.microsoft.com/ado/2007/08/dataservices}'
# compose search filter
filterstring = f"startswith(Name,'S1{sat_ab}') and substringof('{orbit_type}',Name) and ContentDate/Start lt datetime'{start_time}' and ContentDate/End gt datetime'{end_time}'"
# create HTTPS request and get response
params = { '$top': 1, '$orderby': 'ContentDate/Start asc', '$filter': filterstring }
search_response = requests.get(url='https://scihub.copernicus.eu/gnss/odata/v1/Products', params=params, auth=('gnssguest','gnssguest'))
search_response.raise_for_status()
# parse XML tree from response
tree = ElementTree.fromstring(search_response.content)
#extract w3.org URL that gets inserted into all sub-element names for some reason
w3url=tree.tag.split('feed')[0]
# extract the product's hash-value ID
product_ID=tree.findtext(f'.//{w3_url}entry/{m_url}properties/{d_url}Id')
product_url = f"{scihub_url}('{product_ID}')/$value"
product_name=tree.findtext(f'./{w3url}entry/{w3url}title')
# return the orbit name, type, and download URL
if product_ID is not None:
orbit={'name':product_name, 'orbit_type':orbit_type, 'remote_url':product_url}
else:
orbit=None
return orbit
def download_copernicus_orbit_file(dest_folder,remote_url):
"""
Download orbit file returned by the Copernicus GNSS products API.
Inputs: destination folder (absolute or relative path) and the remote URL, with a format like: https://scihub.copernicus.eu/gnss/odata/v1/Products('3a773f7a-0602-44e4-b4c0-609b7f4291f0')/$value
Returns the absolute path of the saved file.
"""
# created by E. Lindsey, April 2021
# check that the output folder exists
os.makedirs(dest_folder, exist_ok = True)
# download the orbit file
dl_response = requests.get(url=remote_url, auth=('gnssguest','gnssguest'))
# find the filename in the header
header = dl_response.headers['content-disposition']
header_value, header_params = cgi.parse_header(header)
#compose the full filename
eof_filename = os.path.abspath(os.path.join(dest_folder,header_params['filename']))
# save the file with the correct filename
open(eof_filename, 'wb').write(dl_response.content)
return eof_filename
def get_dates_from_eof(eof_name):
"""
EOF file has name like S1A_OPER_AUX_POEORB_OPOD_20170917T121538_V20170827T225942_20170829T005942.EOF
Function returns a list of 3 datetime objects matching the strings ['20170917T121538','20170827T225942','20170829T005942']
"""
#make sure we have just the file basename
eof_name = os.path.basename(eof_name)
#parse string by fixed format
date1=datetime.datetime.strptime(eof_name[25:40],'%Y%m%dT%H%M%S')
date2=datetime.datetime.strptime(eof_name[42:57],'%Y%m%dT%H%M%S')
date3=datetime.datetime.strptime(eof_name[58:73],'%Y%m%dT%H%M%S')
return [date1,date2,date3]