124 lines
5.4 KiB
Python
124 lines
5.4 KiB
Python
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#
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# Author: Piyush Agram
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# Copyright 2016
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#
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import logging
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import isceobj
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import os
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import numpy as np
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import datetime
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logger = logging.getLogger('isce.scansarinsar.runEstimateBurstSync')
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def runEstimateBurstSync(self):
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'''Estimate burst sync between acquisitions.
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'''
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swathList = self._insar.getValidSwathList(self.swaths)
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catalog = isceobj.Catalog.createCatalog(self._insar.procDoc.name)
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print('Common swaths: ', swathList)
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if not os.path.isdir(self._insar.burstSyncDirectory):
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os.makedirs(self._insar.burstSyncDirectory)
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for ind, swath in enumerate(swathList):
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##Load master swath
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master = self._insar.loadProduct( os.path.join(self._insar.equalizedMasterSlcProduct,
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's{0}.xml'.format(swath)))
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##Load slave swath
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slave = self._insar.loadProduct( os.path.join(self._insar.equalizedSlaveSlcProduct,
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's{0}.xml'.format(swath)))
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##Replacing Cunren's original high fidelity implementation with simpler more efficient one
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##To estimate burst sync, we dont really need the DEM. Hardly changes with topography
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##Topo impacts range offset but hardly affects azimuth offsets. Hence using a single estimate
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##At mid range and start of middle burst of the master.
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##In the original implementation - topo and geo2rdr were performed to the mid 100 lines of
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##master image. Eventually, offset estimates were averaged to a single number.
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##Our single estimate gets us to that number in a simpler manner.
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###Get mid range for middle burst of master
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midRange = master.startingRange + 0.5 * master.numberOfSamples * master.instrument.rangePixelSize
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midLine = master.burstStartLines[len(master.burstStartLines)//2]
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tmaster = master.sensingStart + datetime.timedelta(seconds = midLine / master.PRF)
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llh = master.orbit.rdr2geo(tmaster, midRange)
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slvaz, slvrng = slave.orbit.geo2rdr(llh)
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###Translate to offsets
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rgoff = ((slvrng - slave.startingRange) / slave.instrument.rangePixelSize) - 0.5 * master.numberOfSamples
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azoff = ((slvaz - slave.sensingStart).total_seconds() * slave.PRF) - midLine
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##Jumping back to Cunren's original code
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scburstStartLine = master.burstStartLines[0] + azoff
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nb = slave.nbraw
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nc = slave.ncraw
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#Slave burst start times corresponding to master burst start times implies 100% synchronization
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scburstStartLines = scburstStartLine + np.arange(-100000, 100000)*nc
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dscburstStartLines = -(slave.burstStartLines[0] - scburstStartLines)
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unsynLines = dscburstStartLines[ np.argmin( np.abs(dscburstStartLines))]
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if np.abs(unsynLines) >= nb:
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synLines = 0
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if unsynLines > 0:
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unsynLines = nb
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else:
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unsynLines = -nb
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else:
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synLines = nb - np.abs(unsynLines)
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##Copy of illustration from Cunren's code
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############################################################# ###############################
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#illustration of the sign of the number of unsynchronized lin es (unsynLines)
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#The convention is the same as ampcor offset, that is,
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# slaveLineNumber = masterLineNumber + unsynLine s
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#
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# |-----------------------| ------------
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# | | ^
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# | | |
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# | | | unsynLines < 0
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# | | |
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# | | \ /
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# | | |-----------------------|
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# | | | |
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# | | | |
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# |-----------------------| | |
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# Master Burst | |
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# | |
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# | |
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# | |
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# | |
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# |-----------------------|
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# Slave Burst
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#
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#
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############################################################# ###############################
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##For now keeping Cunren's text file format.
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##Could be streamlined
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outfile = os.path.join(self._insar.burstSyncDirectory, 's{0}.txt'.format(swath))
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self._insar.writeBurstSyncFile(outfile, rgoff, azoff,
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nb, nc,
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unsynLines, synLines)
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synPerc = (synLines/nb)*100.0
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if synPerc < self.burstOverlapThreshold:
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print('Sync overlap {0} < {1}. Will trigger common azimuth spectra filter for swath {2}'.format(synPerc, self.burstOverlapThreshold, swath))
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else:
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print('Sync overlap {0} >= {1}. No common azimuth spectra filter applied for swath {2}'.format(synPerc, self.burstOverlapThreshold, swath))
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catalog.printToLog(logger, "runEstimateBurstSync")
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self._insar.procDoc.addAllFromCatalog(catalog)
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